climate change research report pdf

• Climate Change - A Global Issue
• Dag Hammarskjöld Library
• Research Guides

Major Reports

• A Global Issue
• At the United Nations
• Books & Journals
• Consulting the Experts
• Keeping up to date
• Data & Statistics
• AR6 - 6th IPCC Assessment Report / Intergovernmental Panel on Climate Change The main activity of the IPCC is to, at regular intervals, provide Assessment Reports of the state of knowledge on climate change. The IPCC is now in its sixth assessment cycle, in which it is producing the Sixth Assessment Report (AR6) with contributions by its three Working Groups and a Synthesis Report, three Special Reports, and a refinement to its latest Methodology Report.

• Global Landscape of Climate Finance 2023 / Climate Policy Initiative Date: 2023 Provides information about which sources and financial instruments are driving investments, and how much climate finance is flowing globally. The report aims to provide an updated picture on how, where, and from whom finance is flowing toward low-carbon and climate-resilient actions globally, and to improve understanding of how public and private sources of finance interact.

• << Previous: At the United Nations
• Next: Books & Journals >>
• Last Updated: May 6, 2024 4:22 PM
• URL: https://research.un.org/en/climate-change

• News, Stories & Speeches
• Get Involved
• Structure and leadership
• Committee of Permanent Representatives
• UN Environment Assembly
• Funding and partnerships
• Policies and strategies
• Evaluation Office
• Secretariats and Conventions
• Asia and the Pacific
• Latin America and the Caribbean
• New York Office
• North America
• Climate action
• Nature action
• Chemicals and pollution action
• Digital Transformations
• Disasters and conflicts
• Environment under review
• Environmental law and governance
• Extractives
• Fresh Water
• Green economy
• Ocean, seas and coasts
• Resource efficiency
• Sustainable Development Goals
• Youth, education and environment
• Publications & data

Climate Change 2023: Synthesis Report

The much-anticipated  Climate Change 2023: Synthesis Report  is based on years of work by hundreds of scientists during the Intergovernmental Panel on Climate Change ’s (IPCC) sixth assessment cycle which began in 2015.

The report provides the main scientific input to COP28 and the Global Stocktake at the end of this year, when countries will review progress towards the Paris Agreement goals.

The report reiterates that humans are responsible for all global heating over the past 200 years leading to a current temperature rise of 1.1°C above pre-industrial levels, which has led to more frequent and hazardous weather events that have caused increasing destruction to people and the planet. The report reminds us that every increment of warming will come with more extreme weather events. 

The report outlines that the 1.5°C limit is still achievable and outlines the critical action required across sectors and by everyone at all levels. The report focuses on the critical need for action that considers climate justice and focuses on climate resilient development. It outlines that by sharing best practices, technology, effective policy measures, and mobilising sufficient finance, any community can decrease or prevent the usage of carbon-intensive consumption methods. The biggest gains in well-being can be achieved by prioritizing climate risk reduction for low-income and marginalized communities.

© 2024 UNEP Terms of Use Privacy   Report Project Concern Report Scam Contact Us

• Ways to Give
• Contact an Expert
• Explore WRI Perspectives

Filter Your Site Experience by Topic

Applying the filters below will filter all articles, data, insights and projects by the topic area you select.

• All Topics Remove filter
• Climate filter site by Climate
• Cities filter site by Cities
• Energy filter site by Energy
• Food filter site by Food
• Forests filter site by Forests
• Freshwater filter site by Freshwater
• Ocean filter site by Ocean
• Business filter site by Business
• Economics filter site by Economics
• Finance filter site by Finance
• Equity & Governance filter site by Equity & Governance

Search WRI.org

Not sure where to find something? Search all of the site's content.

10 Big Findings from the 2023 IPCC Report on Climate Change

• climate change
• Climate Resilience
• climate science
• climatewatch-pinned

March 20 marked the release of the final installment of the Intergovernmental Panel on Climate Change’s (IPCC) Sixth Assessment Report (AR6) , an eight-year long undertaking from the world’s most authoritative scientific body on climate change. Drawing on the findings of 234 scientists on the  physical science of climate change , 270 scientists on  impacts, adaptation and vulnerability to climate change , and 278 scientists on  climate change mitigation , this  IPCC synthesis report  provides the most comprehensive, best available scientific assessment of climate change.

It also makes for grim reading. Across nearly 8,000 pages, the AR6 details the devastating consequences of rising greenhouse gas (GHG) emissions around the world — the destruction of homes, the loss of livelihoods and the fragmentation of communities, for example — as well as the increasingly dangerous and irreversible risks should we fail to change course.

But the IPCC also offers hope, highlighting pathways to avoid these intensifying risks. It identifies readily available, and in some cases, highly cost-effective actions that can be undertaken now to reduce GHG emissions, scale up carbon removal and build resilience. While the window to address the climate crisis is rapidly closing, the IPCC affirms that we can still secure a safe, livable future.

Here are 10 key findings you need to know:

1. Human-induced global warming of 1.1 degrees C has spurred changes to the Earth’s climate that are unprecedented in recent human history.

Already, with 1.1 degrees C (2 degrees F) of global temperature rise, changes to the climate system that are unparalleled over centuries to millennia are now occurring in every region of the world, from rising sea levels to more extreme weather events to rapidly disappearing sea ice.

Additional warming will increase the magnitude of these changes. Every 0.5 degree C (0.9 degrees F) of global temperature rise, for example, will cause clearly discernible increases in the frequency and severity of heat extremes, heavy rainfall events and regional droughts. Similarly, heatwaves that, on average, arose once every 10 years in a climate with little human influence will likely occur 4.1 times more frequently with 1.5 degrees C (2.7 degrees F) of warming, 5.6 times with 2 degrees C (3.6 degrees F) and 9.4 times with 4 degrees C (7.2 degrees F) — and the intensity of these heatwaves will also increase by 1.9 degrees C (3.4 degrees F), 2.6 degrees C (4.7 degrees F) and 5.1 degrees C (9.2 degrees F) respectively.

Rising global temperatures also heighten the probability of reaching dangerous tipping points in the climate system that, once crossed, can trigger self-amplifying feedbacks that further increase global warming, such as thawing permafrost or massive forest dieback. Setting such reinforcing feedbacks in motion can also lead to other substantial, abrupt and irreversible changes to the climate system. Should warming reach between 2 degrees C (3.6 degrees F) and 3 degrees C (5.4 degrees F), for example, the West Antarctic and Greenland ice sheets could melt almost completely and irreversibly over many thousands of years, causing sea levels to rise by several meters.

2. Climate impacts on people and ecosystems are more widespread and severe than expected, and future risks will escalate rapidly with every fraction of a degree of warming.

Described as an “an atlas of human suffering and a damning indictment of failed climate leadership” by United Nations Secretary-General António Guterres, one of AR6’s most alarming conclusions is that adverse climate impacts are already more far-reaching and extreme than anticipated. About half of the global population currently contends with severe water scarcity for at least one month per year, while higher temperatures are enabling the spread of vector-borne diseases, such as malaria, West Nile virus and Lyme disease. Climate change has also slowed improvements in agricultural productivity in middle and low latitudes, with crop productivity growth shrinking by a third in Africa since 1961. And since 2008, extreme floods and storms have forced over 20 million people from their homes every year.

Every fraction of a degree of warming will intensify these threats, and even limiting global temperature rise to 1.5 degree C is not safe for all. At this level of warming, for example, 950 million people across the world’s drylands will experience water stress, heat stress and desertification, while the share of the global population exposed to flooding will rise by 24%.

Similarly, overshooting 1.5 degrees C (2.7 degrees F), even temporarily, will lead to much more severe, oftentimes irreversible impacts, from local species extinctions to the complete drowning of salt marshes to loss of human lives from increased heat stress. Limiting the magnitude and duration of overshooting 1.5 degrees C (2.7 degrees F), then, will prove critical in ensuring a safe, livable future, as will holding warming to as close to 1.5 degrees C (2.7 degrees F) or below as possible. Even if this temperature limit is exceeded by the end of the century, the imperative to rapidly curb GHG emissions to avoid higher levels of warming and associated impacts remains unchanged.

3. Adaptation measures can effectively build resilience, but more finance is needed to scale solutions.

Climate policies in at least 170 countries now consider adaptation, but in many nations, these efforts have yet to progress from planning to implementation. Measures to build resilience are still largely small-scale, reactive and incremental, with most focusing on immediate impacts or near-term risks. This disparity between today’s levels of adaptation and those required persists in large part due to limited finance. According to the IPCC, developing countries alone will need $127 billion per year by 2030 and $295 billion per year by 2050 to adapt to climate change. But funds for adaptation reached just $23 billion to $46 billion from 2017 to 2018, accounting for only 4% to 8% of tracked climate finance.

The good news is that the IPCC finds that, with sufficient support, proven and readily available adaptation solutions can build resilience to climate risks and, in many cases, simultaneously deliver broader sustainable development benefits.

Ecosystem-based adaptation, for example, can help communities adapt to impacts that are already devastating their lives and livelihoods, while also safeguarding biodiversity, improving health outcomes, bolstering food security, delivering economic benefits and enhancing carbon sequestration. Many ecosystem-based adaptation measures — including the protection, restoration and sustainable management of ecosystems, as well as more sustainable agricultural practices like integrating trees into farmlands and increasing crop diversity — can be implemented at relatively low costs today. Meaningful collaboration with Indigenous Peoples and local communities is critical to the success of this approach, as is ensuring that ecosystem-based adaptation strategies are designed to account for how future global temperature rise will impact ecosystems.

4. Some climate impacts are already so severe they cannot be adapted to, leading to losses and damages.

Around the world, highly vulnerable people and ecosystems are already struggling to adapt to climate change impacts. For some, these limits are “soft” — effective adaptation measures exist, but economic, political and social obstacles constrain implementation, such as lack of technical support or inadequate funding that does not reach the communities where it’s needed most. But in other regions, people and ecosystems already face or are fast approaching “hard” limits to adaptation, where climate impacts from 1.1 degrees C (2 degrees F) of global warming are becoming so frequent and severe that no existing adaptation strategies can fully avoid losses and damages. Coastal communities in the tropics, for example, have seen entire coral reef systems that once supported their livelihoods and food security experience widespread mortality, while rising sea levels have forced other low-lying neighborhoods to move to higher ground and abandon cultural sites. 

Whether grappling with soft or hard limits to adaptation, the result for vulnerable communities is oftentimes irreversible and devastating. Such losses and damages will only escalate as the world warms. Beyond 1.5 degrees C (2.7 degrees F) of global temperature rise, for example, regions reliant on snow and glacial melt will likely experience water shortages to which they cannot adapt. At 2 degrees C (3.6 degrees F), the risk of concurrent maize production failures across important growing regions will rise dramatically. And above 3 degrees C (5.4 degrees F), dangerously high summertime heat will threaten the health of communities in parts of southern Europe.

Urgent action is needed to avert, minimize and address these losses and damages. At COP27, countries took a critical step forward by agreeing to establish funding arrangements for loss and damage, including a dedicated fund. While this represents  a historic breakthrough  in the climate negotiations, countries must now figure out the details of what these funding arrangements, as well as the new fund , will look like in practice — and it’s these details that will ultimately determine the adequacy, accessibility, additionality and predictability of these financial flows to those experiencing loss and damage.

5. Global GHG emissions peak before 2025 in 1.5 degrees C-aligned pathways.

The IPCC finds that there is a more than 50% chance that global temperature rise will reach or surpass 1.5 degrees C (2.7 degrees F) between 2021 and 2040 across studied scenarios, and under a high-emissions pathway, specifically, the world may hit this threshold even sooner — between 2018 and 2037. Global temperature rise in such a carbon-intensive scenario could also increase to 3.3 degrees C to 5.7 degrees C (5.9 degrees F to 10.3 degrees F) by 2100. To put this projected amount of warming into perspective, the last time global temperatures exceeded 2.5 degrees C (4.5 degrees F) above pre-industrial levels was more than 3 million years ago.

Changing course to limit global warming to 1.5 degrees C (2.7 degrees F) — with no or limited overshoot — will instead require deep GHG emissions reductions in the near-term. In modelled pathways that limit global warming to this goal, GHG emissions peak immediately and before 2025 at the latest. They then drop rapidly, declining 43% by 2030 and 60% by 2035, relative to 2019 levels.

While there are some bright spots — the annual growth rate of GHG emissions slowed from an average of 2.1% per year between 2000 and 2009 to 1.3% per year between 2010 and 2019, for example — global progress in mitigating climate change remains woefully off track. GHG emissions have climbed steadily over the past decade, reaching 59 gigatonnes of carbon dioxide equivalent (GtCO2e) in 2019 — approximately 12% higher than in 2010 and 54% greater than in 1990.

Even if countries achieved their climate pledges (also known as nationally determined contributions or NDCs),  WRI research  finds that they would reduce GHG emissions by just 7% from 2019 levels by 2030, in contrast to the 43% associated with limiting temperature rise to 1.5 degrees C (2.7 degrees F). And while handful of countries have submitted  new or enhanced NDCs  since the IPCC’s cut-off date,  more recent analysis  that takes these submissions into account finds that these commitments collectively still fall short of closing this emissions gap.

6. The world must rapidly shift away from burning fossil fuels — the number one cause of the climate crisis.

In pathways limiting warming to 1.5 degrees C (2.7 degrees F) with no or limited overshoot just a net 510 GtCO2 can be emitted before carbon dioxide emissions reach net zero in the early 2050s. Yet future carbon dioxide emissions from existing and planned fossil fuel infrastructure alone could surpass that limit by 340 GtCO2, reaching 850 GtCO2.

A mix of strategies can help avoid  locking in  these emissions, including retiring existing fossil fuel infrastructure, canceling new projects, retrofitting fossil-fueled power plants with carbon capture and storage (CCS) technologies and scaling up renewable energy sources like solar and wind (which are now cheaper than fossil fuels in many regions).

In pathways that limit warming to 1.5 degrees C (2.7 degrees F) — with no or limited overshoot — for example, global use of coal falls by 95% by 2050, oil declines by about 60% and gas by about 45%. These figures assume significant use of abatement technologies like CCS, and without them, these same pathways show much steeper declines by mid-century. Global use of coal without CCS, for example, is virtually phased out by 2050.

Although coal-fired power plants are starting to be retired across Europe and the United States, some multilateral development banks continue to invest in new coal capacity. Failure to change course risks stranding assets worth trillions of dollars.

7. We also need urgent, systemwide transformations to secure a net-zero, climate-resilient future.

While fossil fuels are the number one source of GHG emissions, deep emission cuts are necessary across all of society to combat the climate crisis. Power generation, buildings, industry, and transport are responsible for close to 80% of global emissions while agriculture, forestry and other land uses account for the remainder.

Take the  transport system , for instance. Drastically cutting emissions will require urban planning that minimizes the need for travel, as well as the build-out of shared, public and nonmotorized transport, such as rapid transit and bicycling in cities. Such a transformation will also entail increasing the supply of electric passenger vehicles, commercial vehicles and buses, coupled with wide-scale installation of rapid-charging infrastructure, investments in zero-carbon fuels for shipping and aviation and more.

Policy measures that make these changes less disruptive can help accelerate needed transitions, such as subsidizing zero-carbon technologies and taxing high-emissions technologies like fossil-fueled cars. Infrastructure design — like reallocating street space for sidewalks or bike lanes — can help people transition to lower-emissions lifestyles. It is important to note there are many co-benefits that accompany these transformations, too. Minimizing the number of passenger vehicles on the road, in this example, reduces harmful local air pollution and cuts traffic-related crashes and deaths.

Systems Change Lab  monitors, learns from and mobilizes action to achieve the far-reaching transformational shifts needed to limit global warming to 1.5 degrees C, halt biodiversity loss and build a just and equitable economy.

Transformative adaptation measures, too, are critical for securing a more prosperous future. The IPCC emphasizes the importance of ensuring that adaptation measures drive systemic change, cut across sectors and are distributed equitably across at-risk regions. The good news is that there are oftentimes strong synergies between transformational mitigation and adaptation. For example, in the global food system, climate-smart agriculture practices like shifting to  agroforestry  can improve resilience to climate impacts, while simultaneously advancing mitigation.  

8. Carbon removal is now essential to limit global temperature rise to 1.5 degrees C.

Deep decarbonization across all systems while building resilience won’t be enough to achieve global climate goals, though. The IPCC finds that all pathways that limit warming to 1.5 degrees C (2.7 degrees F) — with no or limited overshoot — depend on some quantity of  carbon removal . These approaches encompass both natural solutions, such as sequestering and storing carbon in trees and soil, as well as more nascent technologies that pull carbon dioxide directly from the air.

Hover over each carbon removal approach to learn more:

Note: This figure includes carbon removal approaches mentioned in countries' long-term climate strategies as well as other leading proposed approaches. The natural/biotic vs. technological/abiotic categorization shown here is illustrative rather than definitive and will vary depending on how approaches are applied, particularly for carbon removal approaches in the ocean.

The amount of carbon removal required depends on how quickly we reduce GHG emissions across other systems and the extent to which climate targets are overshot, with estimates ranging from between 5 GtCO2 to 16 GtCO2 per year needed by mid-century.

All carbon removal approaches have merits and drawbacks. Reforestation, for instance, represents a readily available, relatively low-cost strategy that, when implemented appropriately, can deliver a wide range of benefits to communities. Yet the carbon stored within these ecosystems is also vulnerable to disturbances like wildfires, which may increase in frequency and severity with additional warming. And, while technologies like bioenergy with carbon capture and storage (BECCS) may offer a more permanent solution, such approaches also risk displacing croplands, and in doing so, threatening food security. Responsibly researching, developing and deploying emerging carbon removal technologies, alongside existing natural approaches, will therefore require careful understanding of each solution’s unique benefits, costs and risks.

9. Climate finance for both mitigation and adaptation must increase dramatically this decade.

The IPCC finds that public and private finance flows for fossil fuels today far surpass those directed toward climate mitigation and adaptation. Thus, while annual public and private climate finance has risen by upwards of 60% since the IPCC’s Fifth Assessment Report, much more is still required to achieve global climate change goals. For instance, climate finance will need to increase between 3 and 6 times by 2030 to achieve mitigation goals, alone.

This gap is widest in developing countries, particularly those already struggling with debt, poor credit ratings and economic burdens from the COVID-19 pandemic. Recent mitigation investments, for example, need to increase by at least sixfold in Southeast Asia and developing countries in the Pacific, fivefold in Africa and fourteenfold in the Middle East by 2030 to hold warming below 2 degrees C (3.6 degrees F). And across sectors, this shortfall is most pronounced for agriculture, forestry and other land use, where recent financial flows are 10 to 31 times below what is required to achieve the Paris Agreement’s goals.

Finance for adaptation, as well as loss and damage, will also need to rise dramatically. Developing countries, for example, will need $127 billion per year by 2030 and $295 billion per year by 2050. While AR6 does not assess countries’ needs for finance to avert, minimize and address losses and damages,  recent estimates  suggest that they will be substantial in the coming decades. Current funds for both fall well below estimated needs, with the highest estimates of adaptation finance totaling under $50 billion per year.

10. Climate change — as well as our collective efforts to adapt to and mitigate it — will exacerbate inequity should we fail to ensure a just transition.  

Households with incomes in the top 10%, including a relatively large share in developed countries, emit upwards of 45% of the world's GHGs, while those families earning in the bottom 50% account for 15% at most. Yet the effects of climate change already — and will continue to — hit poorer, historically marginalized communities the hardest.

Today, between 3.3 billion and 3.6 billion people live in countries that are highly vulnerable to climate impacts, with global hotspots concentrated in the Arctic, Central and South America, Small Island Developing states, South Asia and much of sub-Saharan Africa. Across many countries in these regions, conflict, existing inequalities and development challenges (e.g., poverty and limited access to basic services like clean water) not only heighten sensitivity to climate hazards, but also limit communities’ capacity to adapt.  Mortality from storms, floods and droughts, for instance, was 15 times higher in countries with high vulnerability to climate change than in those with very low vulnerability from 2010 to 2020.

At the same time, efforts to mitigate climate change also risk disruptive changes and exacerbating inequity. Retiring coal-fired power plants, for instance, may displace workers, harm local economies and reconfigure the social fabric of communities, while inappropriately implemented efforts to halt deforestation could heighten poverty and intensify food insecurity. And certain climate policies, such as  carbon taxes  that raise the cost of emissions-intensive goods like gasoline, can also prove to be regressive, absent of efforts to recycle the revenues raised from these taxes back into programs that benefit low-income communities.

Fortunately, the IPCC identifies a range of measures that can support a just transition and help ensure that no one is left behind as the world moves toward a net-zero-emissions, climate-resilient future. Reconfiguring social protection programs (e.g., cash transfers, public works programs and social safety nets) to include adaptation, for example, can reduce communities’ vulnerability to a wide range of future climate impacts, while strengthening justice and equity. Such programs are particularly effective when paired with efforts to expand access to infrastructure and basic services.

Similarly, policymakers can design mitigation strategies to better distribute the costs and benefits of reducing GHG emissions. Governments can pair efforts to phase out coal-fired electricity generation, for instance, with subsidized job retraining programs that support workers in developing the skills needed to secure new, high-quality jobs. Or, in another example, officials can couple policy interventions dedicated to expanding access to public transit with interventions to improve access to nearby, affordable housing.

Across both mitigation and adaptation measures, inclusive, transparent and participatory decision-making processes will play a central role in ensuring a just transition. More specifically, these forums can help cultivate public trust, deepen public support for transformative climate action and avoid unintended consequences.

Looking Ahead

The IPCC’s AR6 makes clear that risks of inaction on climate are immense and the way ahead requires change at a scale not seen before. However, this report also serves as a reminder that we have never had more information about the gravity of the climate emergency and its cascading impacts — or about what needs to be done to reduce intensifying risks.

Limiting global temperature rise to 1.5 degrees C (2.7 degrees F) is still possible, but only if we act immediately. As the IPCC makes clear, the world needs to peak GHG emissions before 2025 at the very latest, nearly halve GHG emissions by 2030 and reach net-zero CO2 emissions around mid-century, while also ensuring a just and equitable transition. We’ll also need an all-hands-on-deck approach to guarantee that communities experiencing increasingly harmful impacts of the climate crisis have the resources they need to adapt to this new world. Governments, the private sector, civil society and individuals must all step up to keep the future we desire in sight. A narrow window of opportunity is still open, but there’s not one second to waste.

Note: In addition to showcasing findings from the IPCC’s AR6 Synthesis Report, this article also draws on previous articles detailing the IPCC’s findings on  the physical science of climate change ,  impacts, adaption and vulnerability ,  and  climate change mitigation .

Relevant Work

6 takeaways from the 2022 ipcc climate change mitigation report, 6 big findings from the ipcc 2022 report on climate impacts, adaptation and vulnerability, 5 big findings from the ipcc’s 2021 climate report, 8 things you need to know about the ipcc 1.5˚c report.

Join us on March 23 for a high-level webinar featuring IPCC authors, government representatives and leading carbon removal experts to discuss how carbon removal is a critical tool in our toolbox to address the climate crisis.

How You Can Help

WRI relies on the generosity of donors like you to turn research into action. You can support our work by making a gift today or exploring other ways to give.

Stay Informed

World Resources Institute 10 G Street NE Suite 800 Washington DC 20002 +1 (202) 729-7600

© 2024 World Resources Institute

Envision a world where everyone can enjoy clean air, walkable cities, vibrant landscapes, nutritious food and affordable energy.

• Library Web
• Archives Guides
• Ask a Librarian
• United Nations Office at Geneva

• United Nations Library & Archives Geneva
• Research Guides

Climate Change

• Reports & Publications
• Climate Change and the United Nations
• Climate Change and Law / Treaties
• Books & Journals
• News & More

Periodic UN System Reports on Climate Change

• High Level Champions publications At COP21 governments agreed that mobilizing stronger and more ambitious climate action was urgently required. Nations decided to appoint two High-Level Champions, leading to the Climate Champions Team, to help deliver on their mandate to enhance ambition and strengthen the engagement of non-State actors in supporting Parties, working with the Marrakech Partnership, to deliver the goals of the Paris Agreement. The Team supports global campaigns to achieve this work, including the Race to Zero (to rally non-state actors to halve global emissions by 2030 and deliver a healthier, fairer zero carbon world) and the Race to Resilience (to catalyse global ambition for climate resilience).
• Nationally determined contributions under the Paris Agreement. Synthesis report by the secretariat This report synthesizes information from the 168 latest available nationally determined contributions communicated by 195 Parties to the Paris Agreement and recorded in the registry of nationally determined contributions as at 25 September 2023. Published 14 November 2023
• Nationally determined contributions under the Paris Agreement: Synthesis report by the secretariat The 2023 UN Climate Change NDC synthesis report (released 14 November 2023) finds national climate action plans remain insufficient to limit global temperature rise to 1.5 degrees Celsius and meet the goals of the Paris Agreement. The report analyzed the NDCs of 195 Parties to the Paris Agreement, including 20 new or updated NDCs submitted up until 25 September 2023. In line with the findings from last year’s analysis, it shows that while emissions are no longer increasing after 2030, compared to 2019 levels, they are still not demonstrating the rapid downward trend science says is necessary this decade. If the latest available NDCs are implemented, current commitments will increase emissions by about 8.8%, compared to 2010 levels. more... less... 2023 press release: https://unfccc.int/news/new-analysis-of-national-climate-plans-insufficient-progress-made-cop28-must-set-stage-for-immediate 2022 press release: https://unfccc.int/news/climate-plans-remain-insufficient-more-ambitious-action-needed-now 2021 report: https://unfccc.int/documents/306848 2021 press release updated report: https://unfccc.int/news/updated-ndc-synthesis-report-worrying-trends-confirmed
• Advance version: Technical dialogue of the first global stocktake. Synthesis report by the co-facilitators on the technical dialogue - To be discussed at COP28. Published 8 September 2023 more... less... Summary This synthesis report on the technical dialogue of the first global stocktake is based on inputs received throughout the process and discussions held during each of the three meetings of the technical dialogue and serves as an overarching and factual resource that provides a comprehensive overview of discussions held during the technical dialogue, identifying key areas for further action to bridge gaps and addressing challenges and barriers in the implementation of the Paris Agreement. It provides an assessment of the collective progress towards achieving the purpose and long-term goals of the Paris Agreement and informs Parties about potential areas for updating and enhancing their action and support, as well as for enhancing international cooperation for climate action.
• United Nations Climate Change Annual Report The annual report of encompasses the key achievements under the UNFCCC intergovernmental process and the activities of the secretariat, particularly the impacts of those activities in support of the Convention, the Kyoto Protocol and the Paris Agreement. The 2021 report (published in 2022) highlights: outcomes from the 2021 May-June Climate Change Sessions (the first time all Parties came together since COP25 in 2019); the positive outcomes from COP 26 in Glasgow, where Parties adopted the Glasgow Climate Pact, which aims to turn the 2020s into a decisive decade for climate action and support; and where the guidelines for the full implementation of the Paris Agreement were finalized allowing for scaled-up cooperation, the mobilization of additional finance and private sector engagement. more... less... 2021 report: https://unfccc.int/sites/default/files/resource/UNFCCC_Annual_Report_2021.pdf 2020 report: https://unfccc.int/sites/default/files/resource/UNFCCC_Annual_Report_2020.pdf
• Yearbook of Global Climate Action 2020 This fifth Yearbook, published in November 2021 by the UN Framework Convention on Climate Change (UNFCCC) Secretariat, reviews the work carried out under the Marrakech Partnership and the High-Level Champions since the last publication, by; (1) summarizing the state and scope of global climate action in 2021 and the challenges and opportunities around how to track and reflect these efforts, as well as the progress of the global action tools launched in the past year; (2) outlining the key messages around what is needed to accelerate sectoral systems transformation; and (3) presenting the Champions’ vision on the future of the climate action framework and agenda, and how the work feeds into the global stocktake. more... less... 4th Yearbook 2020: https://unfccc.int/documents/267246 UNFCCC: http://unfccc.int/ High-Level Climate Champions for Climate Action: https://unfccc.int/climate-action/marrakech-partnership/actors/meet-the-champions Marrakech Partnership for Global Climate Action: https://unfccc.int/climate-action/marrakech-partnership-for-global-climate-action
• The Climate Risk Landscape: Mapping Climate-related Financial Risk Assessment Methodologies This UNEP Finance Initiative report published in February 2021 and updated in April the same year provides a summary of the key developments across third party climae risk assessment providers since May 2019 and covers both physical and transition risks. In March 2022 the supplement The Climate Risk Tool Landscape was published. more... less... The Climate Risk Tool Landscape: 2022 Supplement - https://www.unepfi.org/publications/the-climate-risk-tool-landscape-2022-supplement/
• An Eye on Methane: International Methane Emissions Observatory Report The 2022 report, the International Methane Emissions Observatory's (IMEO) second annual report, seeks to provide decision makers with a framework of action to track and monitor methane emissions to plan targeted and ambitious action for their mitigation. more... less... IMEO: https://www.unep.org/explore-topics/energy/what-we-do/imeo Press release 2022 report: https://www.unep.org/news-and-stories/press-release/fully-operational-un-methane-observatory-paves-way-steep-emissions
• Frontiers Report The periodic UNEP Frontiers reports draw attention to emerging issues of environmental concern. The 2022 Frontiers report: Noise, Blazes and Mismatches? has two chapters devoted to climate change - Wildfires Under Climate Change: A Burning Issue - and - Phenology: Climate Change Is Shifting the Rhythm of Nature. more... less... Frontiers 2022 report: https://www.unep.org/resources/frontiers-2022-noise-blazes-and-mismatches
• Global Climate Litigation Report The UNEP Global Climate Litigation Report: 2020 Status Review provides an overview of the current state of climate change litigation globally, as well as an assessment of global climate change litigation trends. It finds that a rapid increase in climate litigation has occurred around the world. In 2017 there were 884 cases brought in 24 countries. As of 1 July 2020, the number of cases has nearly doubled with at least 1,550 climate change cases filed in 38 countries. Summaries of significant cases appear throughout this report, and it also describes five types of climate cases that suggest where global climate change litigation may be heading in the coming years. more... less... 2017 report: https://www.unep.org/resources/publication/status-climate-change-litigation-global-review
• Global Status Report for Buildings and Construction This annual report is a reference document published by the UNEP-hosted Global Alliance for Buildings and Construction (GlobalABC). The 2022 report finds that despite a substantial increase in investment and success at a global level lowering the energy intensity of buildings, the sector’s total energy consumption and CO2 emissions increased in 2021 above pre-pandemic levels with the largest increase in the last 10 years and CO2 emissions from buildings operations reaching an all-time high of around 10 GtCO2, around a 5% increase from 2020 and 2% higher than the previous peak in 2019. The buildings and construction sector is not on track to achieve decarbonization by 2050 and the gap between the actual climate performance of the sector and the decarbonization pathway is widening. more... less... 2022 report: https://www.unep.org/resources/publication/2022-global-status-report-buildings-and-construction 2021 report: https://www.unep.org/resources/report/2021-global-status-report-buildings-and-construction
• The Production Gap Report This annual report, launched in 2019 and produced in partnership by the Stockholm Environment Institute, International Institute for Sustainable Development, Climate Analytics, E3G and the United Nations Environment Programme, tracks the discrepancy between governments' planned fossil fuel production and global production levels consistent with limiting warming to 1.5°C or 2°C. The 2023 reports shows that Governments, in aggregate, still plan to produce more than double the amount of fossil fuels in 2030 than what would be consistent with limiting global warming to 1.5°C. more... less... 2023 report: https://productiongap.org/2023report/ 2021 report: http://www.unep.org/resources/report/production-gap-report-2021 2020 report: https://productiongap.org/2020report/ 2019 report: https://www.unep.org/resources/report/production-gap-report-2019
• UNEP Adaptation Gap Report The 2023 edition of the UNEP Adaptation Gap Report, "Underfinanced. Underprepared – Inadequate investment and planning on climate adaptation leaves world exposed" finds that progress on climate adaptation is slowing when it should be accelerating to catch up with rising climate change impacts. The report – which looks at progress in planning, financing and implementing adaptation actions – finds that the adaptation finance needs of developing countries are 10-18 times as big as international public finance flows. This is over 50 per cent higher than the previous range estimate. more... less... 2023 report: https://www.unep.org/resources/adaptation-gap-report-2023 2022 report: https://www.unep.org/resources/adaptation-gap-report-2022 2021 report: https://www.unep.org/resources/adaptation-gap-report-2021 2020 report: https://www.unep.org/resources/adaptation-gap-report-2020 2018 report: https://www.unep.org/resources/adaptation-gap-report-2018 2017 report: https://www.unep.org/resources/adaptation-gap-report-2017 2016 report: https://www.unep.org/resources/adaptation-gap-report-2016 2015 report: https://www.unep.org/resources/adaptation-finance-gap-update 2014 report: https://www.unep.org/resources/adaptation-gap-report-2014
• UNEP Emissions Gap Report The 2023 "Emissions Gap Report: Broken Record - Temperatures hit new highs, yet world fails to cut emissions (again)" is the 14th edition of the annual UNEP report that tracks the gap between where global emissions are heading with current country commitments and where they ought to be to limit warming to 1.5°C, and explores ways to bridge the emissions gap. The 2023 report finds that there has been progress since the Paris Agreement was signed in 2015. Greenhouse gas emissions in 2030, based on policies in place, were projected to increase by 16 per cent at the time of the agreement’s adoption. Today, the projected increase is 3 per cent. However, predicted 2030 greenhouse gas emissions still must fall by 28 per cent for the Paris Agreement 2°C pathway and 42 per cent for the 1.5°C pathway. As things stand, fully implementing unconditional Nationally Determined Contributions (NDCs) made under the Paris Agreement would put the world on track for limiting temperature rise to 2.9°C above pre-industrial levels this century. Fully implementing conditional NDCs would lower this to 2.5°C. more... less... 2023: https://www.unep.org/resources/emissions-gap-report-2023 2022: https://www.unep.org/resources/emissions-gap-report-2022 2021: https://www.unep.org/resources/emissions-gap-report-2021 2020: https://www.unep.org/emissions-gap-report-2020 Emissions Gap Report 10 year summary: https://www.unep.org/resources/emissions-gap-report-10-year-summary
• Navigating New Horizons - A Global Foresight Report on Planetary Health and Human Wellbeing 15 July 2024 report by the UN Environment Programme (UNEP) and the International Science Council (ISC) that examines eight critical global shifts that are accelerating the triple planetary crisis of climate change, nature loss, pollution and waste. The report identifies 18 signals of change that offer a deeper glimpse into potential disruptions. Stressing that adopting better foresight tools will be the best way to help the world anticipate future disruptions, the report also recommends a pluralistic approach, including adopting a new social contract that engages a diverse range of stakeholders, including indigenous people, giving young people a stronger voice, and rethinking measures of progress beyond GDP. more... less... UN News article: https://news.un.org/en/story/2024/07/1152136
• Atlas of Mortality and Economic Losses from Weather, Climate and Water Extremes WMO publication that gives an overview of impacts from weather, climate and water extremes globally from based on disaster data from the Emergency Events Database (EM-DAT). The 2023 update provides data that covers the period 1970 to 2021, while the 2021 edition provides an overview of the period 1970 to 2019. Findings include: extreme weather, climate and water-related events caused nearly 12 000 disasters from 1970-2021, reported economic losses are US$4.3 trillion and rising; the death toll is at 2 million, with 90% are in developing countries; mortality rates have fallen thanks to early warnings. The publication is available in English, French, Russian, Spanish, Chinese and Arabic.
• State of Climate Services WMO report that provides an annual overview on climate services. A climate service is a decision aide derived from climate information that assists individuals and organizations in society to make improved ex-ante decision-making. Climate services are essential for adaptation to climate variability and change. The 2022 State of Climate Services report focuses on the issue of health. WMO has issued annual reports on the state of climate services since 2019 in response to a UN request for more information on adaptation needs of countries. more... less... 2023 report (Health): https://library.wmo.int/idurl/4/68500 2022 report (Energy): https://library.wmo.int/idurl/4/58116 2022 press release: https://public.wmo.int/en/media/press-release/climate-change-puts-energy-security-risk 2022 report interactive digital story map: https://storymaps.arcgis.com/stories/bccf0afe292241959d7d7c10db066514 2022 report: https://storymaps.arcgis.com/stories/bccf0afe292241959d7d7c10db066514 2021 report (Water): https://library.wmo.int/idurl/4/57630 2020 report (Risk Information and Early Warning Systems): https://library.wmo.int/idurl/4/57191 2019 report (Agriculture and Food Security): https://library.wmo.int/idurl/4/56884
• State of Global Water Resources WMO report first published in 2022 to assess the effects of climate, environmental and societal change on the Earth’s water resources. The aim of this annual stocktake is to support monitoring and management of global freshwater resources in an era of growing demand and limited supplies. more... less... Press release 2022: http://o.int/en/media/press-release/state-of-global-water-resources-report-informs-rivers-land-water-storage-and Video presentation of 2021 report: https://youtu.be/-QaXN9I1UNI
• State of the Climate in Africa WMO's The State of the Climate in Africa report provides details of extreme weather and climate change impacts in the entire region, with information on climate indicators including temperatures, ocean heat and acidification, sea level rise and glaciers, as well as on extreme events like tropical cyclones, heatwaves, drought, heavy precipitation and cold waves. It highlights the impacts of the changing climate on agriculture and food security, migration and displacement, socioeconomic development, the environment and ecosystem services. The 2021 is the result of collaboration between the African Union Commission (AUC), the World Meteorological Organization (WMO), and other specialized agencies of the United Nations and is the third in the series, with a special emphasis on water resources, a pivotal sector for human and ecosystem health and sustainable socio-economic development of Africa. more... less... 2021 report: 2021 report: https://library.wmo.int/index.php?lvl=notice_display&id=22125#.Y2PoxnbMKUk See the 2021 press release: https://public.wmo.int/en/media/press-release/state-of-climate-africa-highlights-water-stress-and-hazards
• State of the Climate in Asia The report on the State of the Climate in Asia 2022 is the result of collaboration between NMHSs in the region, the UN Economic and Social Commission for Asia and the Pacific (ESCAP), the World Meteorological Organization (WMO), and other specialized agencies of the United Nations. This multi-agency effort provides a summary of the state of climate, extreme events and their socio-economic impacts in Asia region in 2022. The 2022 report is the third in the series of the report. more... less... 2022: https://library.wmo.int/records/item/66314-state-of-the-climate-in-asia-2022 2021: https://library.wmo.int/records/item/58229-state-of-the-climate-in-asia-2021 2020: https://library.wmo.int/records/item/57695-state-of-the-climate-in-asia-2020
• State of the Climate in Europe The WMO State of the Climate in Europe 2021, is the first edition of climate reports to be published annually by the World Meteorological Organization’s Regional Association for Europe (WMO-RA6) and the European Union's Earth observation programme, Copernicus Climate Change Service (C32). It includes the the invaluable contribution of the National Meteorological and Hydrological Services (NMHSs), WMO Regional Climate Centre Network for Europe, the Copernicus Climate Change Services (C3S), the United Nations (UN) agencies, and the numerous experts and scientists from the region and worldwide. more... less... 2021 report: https://library.wmo.int/index.php?lvl=notice_display&id=22152#.Y2Pnw3bMKUl Press release 2021 report: https://public.wmo.int/en/media/press-release/temperatures-europe-increase-more-twice-global-average
• State of the Climate in Latin America and the Caribbean Extreme weather and climate shocks are becoming more acute in Latin America and the Caribbean, as the long-term warming trend and sea level rise accelerate, according to a new report from the World Meteorological Organization (WMO). The State of the Climate in Latin America and the Caribbean 2022 report shows how climate change is triggering a vicious cycle of events, with spiralling impacts on countries and local communities. more... less... 2022: https://library.wmo.int/records/item/66252-state-of-the-climate-in-latin-america-and-the-caribbean-2022 2021: https://library.wmo.int/records/item/58014-state-of-the-climate-in-latin-america-and-the-caribbean-2021
• State of the Climate in South-West Pacific Weather-related disasters and climate change impacts are unravelling the fabric of society in the South-West Pacific. Sea level rise threatens the future of low-lying islands whilst increasing ocean heat and acidification harms vital and vulnerable marine ecosystems, according to a new report from the World Meteorological Organization (WMO). The State of the Climate in the South-West Pacific 2022 report provides a snapshot of climate indicators including temperatures, sea level rise, ocean heat and acidification, and extreme weather events in 2022. It also highlights the socio-economic risks and impacts on key sectors like agriculture. The report, along with an interactive story map, is one of a series of five regional reports and a global report from WMO providing the latest climate insights to inform decision-making. more... less... 2022: https://library.wmo.int/records/item/66342-state-of-the-climate-in-south-west-pacific-2022 2021: https://library.wmo.int/records/item/58225-state-of-the-climate-in-south-west-pacific-2021 2020: https://library.wmo.int/records/item/57732-state-of-the-climate-in-south-west-pacific-2020
• State of the Global Climate Since 1993, the WMO, through the Commission for climatology and in cooperation with its Members, has issued annual statements on the status of the global climate to provide credible scientific information on climate and its variability. The 2023 report shows that records were once again broken for for greenhouse gas levels, surface temperatures, ocean heat and acidification, sea level rise, Antarctic sea ice cover and glacier retreat. The WMO report confirmed that 2023 was the warmest year on record, with the global average near-surface temperature at 1.45 °Celsius (with a margin of uncertainty of ± 0.12 °C) above the pre-industrial baseline. It was the warmest ten-year period on record. The 2023 report was released ahead of World Meteorological Day on 23 March and sets the scene for a new climate action campaign by the UN Development Programme and WMO (21 March 2024 launch). It will inform discussions at a climate ministerial meeting in Copenhagen on 21-22 March 2024. Dozens of experts and partners contributed to the report, including UN organizations, National Meteorological and Hydrological Services (NMHSs) and Global Data and Analysis Centers, as well as Regional Climate Centres, the World Climate Research Programme (WCRP), the Global Atmosphere Watch (GAW), the Global Cryosphere Watch and Copernicus Climate Change Service operated by ECMWF. more... less... 2023 report: https://wmo.int/publication-series/state-of-global-climate-2023 2022 report: https://library.wmo.int/index.php?lvl=notice_display&id=22265#.ZElBU3ZBxpX 2022 story map: https://storymaps.arcgis.com/stories/6d9fcb0709f64904aee371eac09afbdf 2021 report: https://library.wmo.int/index.php?lvl=notice_display&id=22080#.YoZJ_NpBzcs 2021 interactive story: https://storymaps.arcgis.com/stories/bbe6a05f6dae42f2a420cfdd7698e4b1 2020 report: https://library.wmo.int/index.php?lvl=notice_display&id=21880#.YYVQX51KjIV
• United in Science This annual report is compiled by the World Meteorological Organization (WMO) under the direction of the UN Secretary-General to bring together the latest climate science related updates from a group of key global partner organizations. The 2022 report features updates from WMO, Global Carbon Project (GCP), Intergovernmental Panel on Climate Change (IPCC), United Nations Environment Programme (UNEP), The United Nations Office for Disaster Risk Reduction (UNDRR), Met Office (United Kingdom), Urban Climate Change Research Network (UCCRN) and World Climate Research Programme (WCRP - jointly sponsored by WMO/Intergovernmental Oceanographic Commission(IOC)-UNESCO and the International Science Council (ISC). One of the key conclusions of the report: far more ambitious action is needed, if we are to avoid the physical and socioeconomic impacts of climate change having an increasingly devastating effect on the planet. more... less... 2022: https://library.wmo.int/index.php?lvl=notice_display&id=22128#.YyF5DnZBzIV 2021: https://library.wmo.int/index.php?lvl=notice_display&id=21946#.YUIhGGb7TX0 2020: https://library.wmo.int/index.php?lvl=notice_display&id=21761#.Ya82CNDMLIU 2019: https://library.wmo.int/index.php?lvl=notice_display&id=21523#.Ya82GtDMLIU
• WMO Bulletin The Bulletin is produced biannually in English, French, Russian and Spanish editions. It contains articles on all aspects of meteorology, climatology, hydrology, the environment and related fields, that are specifically prepared for the journal. Each issue is planned around a selected theme considered to be of topical interest.
• WMO Global Annual to Decadal Climate Update The Global Annual to Decadal Update is one of a suite of WMO climate products, including the flagship State of the Global Climate, which seek to inform policy-makers. The UK’s Met Office acts as the WMO Lead Centre for Annual to Decadal Climate Prediction, which harnesses expertise of climate scientists and prediction systems around the world to produce actionable information looking at climate predictions for the coming five year period. According to the 2023 update, there is a 66% likelihood that the annual average near-surface global temperature between 2023 and 2027 will be more than 1.5°C above pre-industrial levels for at least one year, and a 98% likelihood that at least one of the next five years, and the five-year period as a whole, will be the warmest on record. more... less... Global Annual to Decadal Climate Update released May 2023 for 2023-2027: https://library.wmo.int/index.php?lvl=notice_display&id=22272#.ZGTEbXZBxmM 2022-2026: https://library.wmo.int/index.php?lvl=notice_display&id=22083#.YoODWZ0zaUk 2021-2025: https://library.wmo.int/index.php?lvl=notice_display&id=22082 2020-2024: https://library.wmo.int/index.php?lvl=notice_display&id=22081
• WMO Greenhouse Gas Bulletin Published annually by WMO in Arabic, Chinese, English, French, Russian and Spanish, the bulletin contains the latest analysis of observations from the WMO Global Atmosphere Watch (GAW) Programme and shows the globally averaged mole fractions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) and compares them with the mole fractions during the previous year and with preindustrial levels. According to the 2023 bulletin, the abundance of heat-trapping greenhouse gases in the atmosphere once again reached a new record last year with no end in sight to the rising trend. more... less... 2023 Bulletin (no. 19): https://wmo.int/resources/publications/wmo-greenhouse-gas-bulletin-no-19 2023 press release: https://wmo.int/news/media-centre/greenhouse-gas-concentrations-hit-record-high-again 2022 Bulletin (no. 18): https://library.wmo.int/index.php?lvl=notice_display&id=22149#.Y10XNXZBzIU 2021 Bulletin (no. 17): https://library.wmo.int/index.php?lvl=notice_display&id=21975 Previous bulletins: https://library.wmo.int/index.php?lvl=notice_display&id=3030#.YYVR4J1KjIV
• WMO Statement on the state of the Global Climate Since 1993, the World Meteorological Organization (WMO), through the Commission for climatology and in cooperation with its Members, has issued annual statements on the status of the global climate to provide credible scientific information on climate and its variability.
• UNDP Nationally Determined Contributions (NDC) Global Outlook Report The UN Development Programme (UNDP) and UN Climate Change (UNFCCC) have been working together since 2014 to support countries in developing Nationally Determined Contributions - or NDCs. The 2022 report, The State of Climate Ambition Regional Snaphots provide regional analysis of Climate Promise supported countries NDC status and implementation readiness. The 2021 report, The State of Climate Ambition, explores trends emerging from "second-generation" pledges under the Paris Agreement and the opportunities being missed to accelerate climate action. The 2019 report, The Heat is On - Taking Stock of Global Climate Ambition, informed the UN Secretary-General's Climate Summit (September 2019). more... less... 2022 report: https://www.undp.org/publications/state-climate-ambition Africa: https://www.undp.org/sites/g/files/zskgke326/files/2022-07/UNDP-The-State-of-Climate-Ambition-Africa.pdf Arab States: https://www.undp.org/sites/g/files/zskgke326/files/2022-07/UNDP-The-State-of-Climate-Ambition-Arab-States.pdf Asia and the Pacific: https://www.undp.org/sites/g/files/zskgke326/files/2022-07/UNDP-The-State-of-Climate-Ambition-Asia-Pacific.pdf Europe and Central Asia: https://www.undp.org/sites/g/files/zskgke326/files/2022-07/UNDP-The-State-of-Climate-Ambition-ECIS.pdf Latin America and the Caribbean: https://www.undp.org/sites/g/files/zskgke326/files/2022-07/UNDP-The-State-of-Climate-Ambition-LAC.pdf See also UNDP Climate Promise Progress Report : https://www.undp.org/publications/undp-climate-promise-progress-report 2021 report: https://www.undp.org/publications/nationally-determined-contributions-ndc-global-outlook-report-2021-state-climate https://www.undp.org/sites/g/files/zskgke326/files/2021-11/UNDP-NDC-Global-Outlook-Report-2021-The-State-of-Climate-Ambition-V2.pdf 2019 report: https://outlook.ndcs.undp.org/ https://www.undp.org/publications/ndc-global-outlook-report-2019 https://www.undp.org/sites/g/files/zskgke326/files/publications/NDC_Outlook_Report_2019.pdf
• Health and Climate Change Country Profiles These profiles, developed in collaboration with national governments, are part of the World Health Organization's monitoring of health sector response to climate change. The profiles summarize evidence of the climate hazards and health risks facing countries, track national progress in addressing the health threats from climate change and highlight opportunities for gaining health benefits from climate mitigation action. The profiles also provide an overview of key areas for taking action and provide links to available resources series.
• Health and Climate Change Global Survey WHO periodic report that tracks global progress on health sector response to climate change through country survey sent to the national health authorities, who in collaboration with other relevant ministries and stakeholders, provide updated information on key areas including: leadership and governance, national vulnerability and adaptation assessments, emergency preparedness, disease surveillance, adaptation and resilience measures, climate and health finance, and mitigation in the health sector. more... less... 2021 report: https://apps.who.int/iris/handle/10665/348068 2017/2018 survey: https://www.who.int/publications/i/item/who-health-and-climate-change-survey-report-tracking-global-progress
• Health and Climate Change Urban Profiles The urban profiles, developed by the World Health Organization in collaboration with local governments, key stakeholders and international partners present a snapshot of climate change hazards and related health risks. They are a resource to raise awareness of health threats from climate hazards, summarize local adaptation and mitigation policies, identify benefits from tackling climate change and strengthen the case for action.
• Global Opportunity Report Series Report published by the UN Global Compact that investigates six sectors and analyzes how selected companies have turned climate risks into climate opportunities.
• Greening the Blue This yearly report details the UN System's environmental footprint and efforts to reduce it. Coordinating this work is the responsibility of the Sustainable United Nations (SUN) facility, working closely with focal points designated by UN organisations who are members of the Environment Management Group (EMG). more... less... Sustainable United Nations (SUN) facility: https://www.unep.org/about-un-environment/sustainability/sustainable-united-nations UN Environment Management Group: https://unemg.org/ 2022 report: https://www.greeningtheblue.org/reports/greening-blue-report-2022
• IMF Staff Climate Notes Series by the International Monetary Fund that aims to quickly disseminate succinct IMF analysis on critical economic issues to member countries and the broader policy community. The IMF Staff Climate Notes provide analysis related to the impact of climate change on macroeconomic and financial stability, including on mitigation, adaptation, and transition. The views expressed in IMF Staff Climate Notes are those of the author(s), although they do not necessarily represent the views of the IMF, or its Executive Board, or its management.
• Special Rapporteur on climate change annual thematic reports on the promotion and protection of human rights in the context of climate change The mandate of the Special Rapporteur on the promotion and protection of human rights in the context of climate change was established by the UN Human Rights Council at its 48th session in October 2021 (RES/48/14).
• Special Rapporteur on human rights and the environment annual thematic reports The Special Rapporteur submits a report to the UN Human Rights Council as well as to the UN General Assembly on an annual basis, as mandated by the UN Human Rights Council resolution 37/8.
• The State of the World's Forests Biennial flagship publication by the UN Food and Agriculture Organization (FAO) that contains extensive data on global forest resources and humans' interaction with them, and outlines strategies for reducing deforestation. The report, available in the six official UN languages, considers both pressures on forests from climate change, as well as the contributions that forests make towards meeting global challenges such as climate change. more... less... 2024 report press release: https://www.fao.org/newsroom/detail/forests-face-increasing-climate-related-stress-amid-growing-demand-for-their-products--fao-report-warns/en 2023 UN news story: https://news.un.org/en/story/2024/07/1152386
• The Sustainable Development Goals Report This annual United Nations report reviews progress of the 2030 Agenda for Sustainable Development. more... less... 2022 report: https://unstats.un.org/sdgs/report/2022/
• Trade and Environment Review Periodic report by UNCTAD focused on trade and the environment. The 2021 edition examines the physical impacts of climate change and effects on developing country economies and trade; the vulnerabilities of developing countries to climate change; costs and finance for climate change adaptation; and ways that developing countries can enhance the resilience of their trade to climate change through adaptation actions and economic diversification. more... less... Trade and Environment Review 2021: https://unctad.org/webflyer/trade-and-environment-review-2021
• UNECE support for climate action Publication that focuses on the practical tools the UN Economic Commission for Europe provides to support countries in their climate change mitigation and adaptation efforts, to leverage financing, and to strengthen collaboration. more... less... 2023: https://unece.org/sites/default/files/2023-10/UNECE%20Climate%20Action_Brochure_WEB%20%282%29.pdf 2022: https://unece.org/sites/default/files/2022-11/UNECE%20Climate%20Action_Brochure_WEB%20%282%29.pdf

IPCC Reports

• Special Reports
• IPCC Reports The Intergovernmental Panel on Climate Change (IPCC) prepares comprehensive Assessment Reports about knowledge on climate change, its causes, potential impacts and response options. The IPCC also produces Special Reports, which are an assessment on a specific issue and Methodology Reports, which provide practical guidelines for the preparation of greenhouse gas inventories.

AR6 Synthesis Report: Climate Change 2022

The IPCC is currently in its Sixth Assessment cycle, during which the IPCC will produce the Assessment reports of its three Working Groups, three Special Reports, a refinement to the methodology report and the Synthesis Report.  The Synthesis Report will be the last of the AR6 products, due for release in late 2022 or early 2023.

AR6 Climate Change 2022: Mitigation of Climate Change

The Working Group III contribution to the Sixth Assessment Report was finalized 4 April 2022.

AR6 Climate Change 2022: Impacts, Adaptation and Vulnerability

The Working Group II contribution to the Sixth Assessment Report was released 28 February 2022.

AR6 Climate Change 2021: The Physical Science Basis

The Working Group I contribution to the Sixth Assessment Report (August 2021) is the most up-to-date physical understanding of the climate system and climate change, bringing together the latest advances in climate science, and combining multiple lines of evidence from paleoclimate, observations, process understanding, and global and regional climate simulations.

The Ocean and Cryosphere in a Changing Climate

The IPCC approved and accepted the Special Report on the Ocean and Cryosphere in a Changing Climate  at its 51st Session held on 20 – 23 September 2019. The approved Summary for Policymakers (SPM) was presented at a press conference on 25 September 2019. The report highlights the urgency of prioritizing timely, ambitious and coordinated action to address unprecedented and enduring changes in the ocean and cryosphere. The report reveals the benefits of ambitious and effective adaptation for sustainable development and, conversely, the escalating costs and risks of delayed action.

Climate Change, Desertification, Land Degradation, Sustainable Land Management, Food Security, and Greenhouse gas fluxes in Terrestrial Ecosystems

This Special Report on Climate Change and Land by the Intergovernmental Panel on Climate Change published in August 2019 responds to the Panel decision in 2016 to prepare three Special Reports during the Sixth Assessment cycle, taking account of proposals from governments and observer organizations. This report addresses greenhouse gas (GHG) fluxes in land-based ecosystems, land use and sustainable land management in relation to climate change adaptation and mitigation, desertification, land degradation and food security.

2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

The 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories was adopted and accepted during the 49th Session of the IPCC in May 2019. It was prepared by the Task Force on National Greenhouse Gas Inventories (TFI) in accordance with the decision taken at the 44th Session of IPCC in Bangkok, Thailand, in October 2016.

Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation  (March 2012)

Renewable Energy Sources and Climate Change Mitigation  (April 2011)

AR5: Fifth Assessment Report of the IPCC

Synthesis Report: Climate Change 2014

The Synthesis Report (SYR) of the IPCC Fifth Assessment Report (AR5) provides an overview of the state of knowledge concerning the science of climate change, emphasizing new results since the publication of the IPCC Fourth Assessment Report (AR4) in 2007.

Climate Change 2013: The Physical Science Basis

The Working Group I contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) provides a comprehensive assessment of the physical science basis of climate change since 2007 when the Fourth Assessment Report (AR4) was released.

AR5 Climate Change 2014: Impacts, Adaptation, and Vulnerability

The assessment of impacts, adaptation, and vulnerability in the Working Group II contribution to the IPCC’s Fifth Assessment Report (WGII AR5) evaluates how patterns of risks and potential benefits are shifting due to climate change since 2007 when the Fourth Assessment Report (AR4) was released.

AR5 Climate Change 2014: Mitigation of Climate Change

The Working Group III contribution to the IPCC’s Fifth Assessment Report (AR5) assesses literature on the scientific, technological, environmental, economic and social aspects of mitigation of climate change since 2007 when the Fourth Assessment Report (AR4) was released.

AR4: Fourth Assessment Report of the IPCC

AR4 Climate Change 2007: Synthesis Report

AR4 Climate Change 2007: Impacts, Adaptation, and Vulnerability

AR4 Climate Change 2007: The Physical Science Basis

AR4 Climate Change 2007: Mitigation of Climate Change

Latest Climate Change reports posted to Reliefweb

• Reliefweb: Climate Change & Environment, all updates & reports

GEF reports

• Selected recent reports
• The Global Environment Facility (GEF) - Publications The GEF is an international partnership of 184 countries, international institutions, civil society organizations and the private sector that addresses global environmental issues. The GEF Trust Fund was established on the eve of the 1992 Rio Earth Summit to help tackle the planet's most pressing environmental problems. GEF funds are available to developing countries and countries with economies in transition to meet the objectives of the international environmental conventions and agreements. The Publications page links to resources dating back to 2000.
• The Capacity-building Initiative for Transparency (CBIT)
• Financing Adaptation to Climate Change at the GEF
• The GEF and Climate Change - Catalysing Transformation
• Reflecting on 30 Years of the GEF
• UNFCCC Guidance from the COPs and Responses by the GEF: COP1-COP25

Select non-UN reports, articles, resources on Climate Change

• Annual/Periodic
• 2019 & earlier
• Climate Bulletins
• Climate Finance and the USD 100 Billion Goal
• Climate Transparency Report
• Environmental Performance Index Report more... less... 2022 report: https://epi.yale.edu/downloads/epi2022report06062022.pdf EPI archive: https://sedac.ciesin.columbia.edu/data/collection/epi/sets/browse
• European State of the Climate more... less... 2022: https://climate.copernicus.eu/esotc/2022
• The Forest Declaration Assessment more... less... 2023 Assessment: https://forestdeclaration.org/resources/forest-declaration-assessment-2023/
• GHG emissions of all world countries
• Global Climate Highlights
• Global Energy Review more... less... 2021 report: https://www.iea.org/reports/global-energy-review-co2-emissions-in-2021-2
• Lancet Countdown on Health and Climate Change Report more... less... 2023 report: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(23)01859-7/fulltext 2022 report: https://www.lancetcountdown.org/2022-report/ 2021 report: https://www.lancetcountdown.org/2021-report/ 2020 report: https://www.lancetcountdown.org/2020-report/ 2019 report: https://www.lancetcountdown.org/2019-report/
• National Climate Assessment
• Renewables more... less... Renewables 2022 - report released December 2022: https://www.iea.org/reports/renewables-2022
• State of Climate Action more... less... 2023 report: https://www.wri.org/research/state-climate-action-2023 2022 report: https://www.wri.org/research/state-climate-action-2022 2021 report: https://www.wri.org/research/state-climate-action-2021 2020 report: https://www.wri.org/research/state-climate-action-assessing-progress-toward-2030-and-2050
• World Energy Outlook more... less... 2023 report: https://www.iea.org/reports/world-energy-outlook-2023 2022 report: https://www.iea.org/reports/world-energy-outlook-2022 2021 report: https://www.iea.org/reports/world-energy-outlook-2021
• A Multitemporal Snapshot of Greenhouse Gas Emissions from the Israel-Gaza Conflict January 2024 paper that examines the projected emissions from the first 60 das of the Israel Gaza war, also considering the war infrastructure built by both Hamas and Israel, and the carbon costs of reconstructing Gaza. The paper argues that the ad-hoc nature of the calculations points to the urgent need for mandatory military emissions reporting through the UNFCCC.
• The Carbon Majors Database Launch Report This April 2024 report by InfluenceMap using the Carbon Majors database quantifies the contribution of the world’s largest oil, gas, coal, and cement producers to global carbon emissions, which are the primary driver of climate change. This report shows that the majority of global CO2 emissions produced since the Paris Agreement can be traced to a small group of high emitters who are failing to slow production. more... less... PDF: https://influencemap.org/site//data/000/027/Carbon_Majors_Launch_Report.pdf
• ICJ to Rule on States' Climate-related Obligations: How Did We Get Here? This March 2024 policy brief by Elena Kosolapova published on the SDG Knowledge Hub of the International Insitute for Sustainable Development provides an overview of the request submitted by the UN General Assembly (UNGA) on 29 March 2023 in A/RES/77/276 to the International Court of Justice (ICJ) for an advisory opinion on the obligations of States under international law to ensure the protection of the climate system and the legal consequences under these obligations for States that have caused harm to the climate system, and with adverse effects for States and present and future generations of people. The Policy Brief links to documents transmitted by the UN Secretariat to the ICJ in support of the UNGA request, and provides status of the request. An advisory opinion of the ICJ is expected in early 2025.
• Big Oil Reality Check May 2024 report by Oil Change International that examines the climate pledges and plans of 8 international oil and gas companies and finds they fail to align with international agreements to phase out fossil fuels and to limit global temperature rise to 1.5ºC. more... less... pdf: https://www.oilchange.org/wp-content/uploads/2024/05/big_oil_reality_check_may_21_2024.pdf
• Scottish scientist Jim Skea elected as the UN climate panel’s new ‘nudger-in-chief’ 24 July 2024 article by Geneva Solutions on the elections of Scottish scientist Jim Skea as the chair of the International Governmental Panel on Climate Change (IPCC). more... less... Welcoming remarks of the chair at the IPCC's 61st plenary: https://www.ipcc.ch/2024/07/27/welcome-remarks-ipcc-chair-jim-skea-ipcc-61/
• Climate mitigation and biodiversity conservation : a review of progress and key issues in global carbon markets and potential impacts on ecosystems 2024 publication by the IUCN (International Union for Conservation of Nature) that presents a current synopsis of the carbon market mechanisms implemented around the world, how these mechanisms are related to natural ecosystems, the potential impacts of their operation, and the potential contribution of natural ecosystems in the design of Nature-based Solutions to reducing carbon emissions. more... less... pdf download: https://portals.iucn.org/library/sites/library/files/documents/2024-022-En.pdf
• 10 actions for greener parliaments 2023 publication from the IPU Secretariat that identifies 10 key actions parliaments and parliamentarians can undertake to help address the climate crisis and pave the way for stronger climate action. more... less... English pdf: https://www.ipu.org/file/16289/download French pdf: https://www.ipu.org/file/16290/download Spanish pdf: https://www.ipu.org/file/16291/download Arabic pdf: https://www.ipu.org/file/16340/download
• Addressing Loss and Damage: What can we learn from countries’ National Adaptation Plans? May 2023 report published by the NAP Global Network that showcases the role of NAP processes in minimizing and addressing loss and damage through a systematic review of NAP documents and interviews with key informants. It provides insights into how loss and damage information is presented in relation to adaptation efforts and how adaptation priorities identified in the NAPs have the potential to respond to loss and damage.
• Another Year of Record Heat for the Oceans January 2023 article published in Advances in Atmospheric Sciences that examines the ocean heat content (OHC) for 2022, which indicate that the world's ocean were again the hottest in the historical record and exceed the previous 2021 record maximum. Water cycels have been profoundly altered due to the emission of greenhouse gases and other anthropogenic substances by human activities, driving pervasive changes in Earth's climate system.
• Burning Billions: Record public money for fossil fuels impeding climate action November 2023 report by IISD provides the latest data on global public financial flows to fossil fuels and clean energy in advance of UN Climate Change Conference COP 28.
• Climate Equality: A planet for the 99% November 2023 Oxfam report that examines the twin crises of climate breakdown and runaway inequality and calls for a radical reduction in inequality, transformative climate action and fundamentally shifting society's economic goals in order to save the planet and ensure wellbeing for all. more... less... Arabic executive summary: https://oi-files-d8-prod.s3.eu-west-2.amazonaws.com/s3fs-public/2023-11/Executive%20summary_Climate%20Equality_Arabic.pdf French executive summary: https://oi-files-d8-prod.s3.eu-west-2.amazonaws.com/s3fs-public/2023-11/VF%20Resume%CC%81%20executif_Oxfam_Franc%CC%A7ais%20.pdf Spanish executive summary: https://oi-files-d8-prod.s3.eu-west-2.amazonaws.com/s3fs-public/2023-11/Executive%20Summary%20Climate%20Equality_ESPANOL.pdf
• A climate finance framework: decisive action to deliver on the Paris Agreement The summary of the second report of the Independent High-Level Expert Group in Climate Finance (IHLEG) was published November 2023. The IHLEG was tasked by the COP26 and COP27 Presidencies to help develop and put forward policy options and recommendations to encourage and enable the public and private investment and finance necessary for delivery of the commitments, ambition, initiatives and targets of the UNFCCC Paris Agreement, reinforced by the Glasgow Climate Pact, and the Sharm el-Sheikh agenda. The full report is due in 2024. more... less... PDF summary: https://www.lse.ac.uk/granthaminstitute/wp-content/uploads/2023/11/A-Climate-Finance-Framework-IHLEG-Report-2-SUMMARY.pdf
• Financing a 1.5˚C-Aligned Transition This July 2023 briefing paper published by IISD builds on the analysis of the most influential modeled pathways consistent with limiting warming to 1.5°C to provide financial institutions with Paris-aligned investment criteria and strategies.
• International Public Opinion on Climate Change, 2023 November 2023 report by the Yale Program on Climate Change Communication, Data for Good at Meta, and Rare's Center for Behavior and the Environment, which results from an international survey investigating public climate change knowledge, beliefs, attitudes, policy preferences and behavior among Facebook users.
• Nature-based Solutions for corporate climate targets : views regarding the corporate use of Nature-based Solutions to meet net-zero goals 2023 publication by IUCN (International Union for Conservation of Nature) that outlines the available pathways to include nature-based solutions (NbS) in corporate climate strategies consistent with the NbS definition, principles and Global Standard for NbS™. When correctly implemented, NbS can contribute to climate mitigation and adaptation while offering important benefits for biodiversity and human well-being. more... less... pdf English: https://portals.iucn.org/library/sites/library/files/documents/2023-032-En.pdf pdf Spanish: https://portals.iucn.org/library/sites/library/files/documents/2023-032-Es.pdf pdf French: https://portals.iucn.org/library/sites/library/files/documents/2023-032-Fr.pdf
• Quantifying the human cost of global warming May 2023 article published in Nature Sustainability that examines the human costs of climate change, expressed in terms of numbers of people left outside the ‘human climate niche’. By end-of-century (2080–2100), current policies leading to around 2.7 °C global warming could leave one-third (22–39%) of people outside this niche. The article highlights the need for more decisive policy action to limit the human costs and inequities of climate change.
• Shifting Public Financial Flows From Fossil Fuels to Clean Energy Under the Paris Agreement The March 2023 report by the International Institute for Sustainable Development is their Energy Program Submission to the UNFCCC First Global Stocktake, and assesses global progress made on aligning public financial flows —such as subsidies and other forms of government support —with the need to reduce emissions within a pathway for a safe climate.
• The State of Carbon Dioxide Removal 2023 global assessment of the state of CDR; the project has been devised and convened by researchers Oliver Geden (German Institute for International and Security Affairs, SWP), Jan Minx (Mercator Research Institute on Global Commons and Climate Change, (MCC), Berlin), Gregory Nemet (University of Wisconsin-Madison) and Stephen M Smith (University of Oxford), and led by the University of Oxford’s Smith School of Enterprise and the Environment. The report finds a gap between proposed CDR deployment and what will be needed to meet the Paris temperature goal to limit warming to well below 2°C and pursue efforts to achieve 1.5°C. more... less... Download the report: https://www.stateofcdr.org/s/SoCDR-1st-edition-2023-V9.pdf
• 1.5°C Pathways for the EU27: accelerating climate action to deliver the Paris Agreement more... less... report PDF: https://climateanalytics.org/media/1-5pathwaysforeu27-2022.pdf
• 2022 Global Food Policy Report: Climate Change and Food Systems more... less... https://www.ifpri.org/publication/2022-global-food-policy-report-climate-change-and-food-systems PDF: https://www.ifpri.org/cdmref/p15738coll2/id/135889/filename/136101.pdf
• Climate change anxiety and mental health: Environmental activism as buffer
• Climate Collateral: How military spending accelerates climate breakdown
• Climate Endgame: Exploring catastrophic climate change scenarios more... less... https://doi.org/10.1073/pnas.210814611
• Environment of Peace: Security in a New Era of Risk more... less... Environment of Peace initiative: https://www.sipri.org/research/peace-and-development/environment-peace
• Estimating the military's global greenhouse gas emissions
• Exceeding 1.5°C global warming could trigger multiple climate tipping points more... less... Read the overview from the Potsdam Institute for Climate Impact Research here: https://www.pik-potsdam.de/en/news/latest-news/risk-of-passing-multiple-climate-tipping-points-escalates-above-1-5degc-global-warming
• Finance for climate action: scaling up investment for climate and development more... less... Full report pdf: https://www.lse.ac.uk/granthaminstitute/wp-content/uploads/2022/11/IHLEG-Finance-for-Climate-Action-1.pdf
• Forests for Climate: Scaling up Forest Conservation to Reach Net Zero more... less... report PDF: https://www3.weforum.org/docs/WEF_Forests_for_Climate_2022.pdf
• High temperatures exacerbated by climate change made 2022 Northern Hemisphere droughts more likely more... less... Full study pdf: https://www.worldweatherattribution.org/wp-content/uploads/WCE-NH-drought-scientific-report.pdf
• Just energy transition partnerships in the context of Africa-Europe relations: Reflections from South Africa, Nigeria and Senegal
• La Genève internationale et l'urgence climatique
• The Land Gap Report
• Loss and Damage finance in the climate negotiations
• Mapping Report on Climate Change Laws and Policies in Climate Vulnerable Countries more... less... Report pdf: https://thecvf.org/wp-content/uploads/2022/06/GLOBE-CVF-Climate-Laws-Report-June-2022.pdf
• National attribution of historical climate damages
• Navigating Energy Transitions: Mapping the road to 1.5°C
• Net zero guidelines: ISO IWA 42:2022
• The Paris Agreement's Global Stocktake: Integrating Non-Party Stakeholders into an Inclusive Stocktake
• Reporting extreme weather and climate change: a guide for journalists more... less... English pdf: https://www.worldweatherattribution.org/wp-content/uploads/ENG_WWA-Reporting-extreme-weather-and-climate-change.pdf French pdf: https://www.worldweatherattribution.org/wp-content/uploads/FR_WWA-Les-evenements-meteorologiques-extremes-et-le-changement-climatique.pdf
• The Science of Climate Impacts: Eight humanitarian insights from the latest IPCC report more... less... Publication pdf: https://www.climatecentre.org/wp-content/uploads/The-Science-of-Climate-Impact_IPCCAR6-WG2-cartoon-summary.pdf
• Solar geoengineering: The case for an international non-use agreement
• The State of Nationally Determined Contributions: 2022
• Trade and Climate Change - What yardstick for net-zero?
• Understanding and responding to the protection needs of climate activists and movements more... less... Full report pdf: https://www.universal-rights.org/download.php?file=https://www.universal-rights.org/wp-content/uploads/2022/05/Report-increasing-support-for-climate-activists.pdf
• World Trade Report 2022: Climate Change and International Trade
• #The time is now - The case for universal recognition of the right to a safe, clean, healthy and sustainable environment more... less... Full report pdf: https://www.universal-rights.org/download.php?file=https://www.universal-rights.org/wp-content/uploads/2021/02/2021_URG_R2HE_TIME_REPORT_MM.pdf
• Arab Climate Futures more... less... PDF: https://www.iss.europa.eu/sites/default/files/EUISSFiles/CP_170_0.pdf
• Call for emergency action to limit global temperature increases, restore biodiversity, and protect health
• Climate Change and the Global Inequality of Carbon Emissions, 1990-2020 more... less... Study: https://wid.world/document/climate-change-the-global-inequality-of-carbon-emissions-1990-2020-world-inequality-lab-working-paper-2021-21/ Data: https://wid.world/world#lpfghg_p90p100_z/US;FR;DE;CN;ZA;GB;WO/2019/eu/k/p/yearly/l/false/2.92/100/curve/false/country
• COP26: What Happened, What Does This Mean, and What Happens Next
• Financing Climate Action and the COVID-19 Pandemic: An Analysis of 17 Developing Countries
• Gender and national climate planning
• Managing Climate Risks, Facing up to Losses and Damages
• Net Zero by 2050: A Roadmap for the Global Energy Sector
• Pathways of climate resilience over the 21st century
• The Physical Science of Climate Change: Seven key humanitarian insights from the latest IPCC report more... less... Publication pdf: https://www.climatecentre.org/wp-content/uploads/IPCC-AR6-WG1-SPM-Cartoon_infused-humanitarian-insights-.pdf ICRC blog post: https://blogs.icrc.org/inspired/2021/08/17/the-physical-science-of-climate-change-seven-key-humanitarian-insights-from-the-2021-ipcc-report/
• Trade and Climate Change - Mapping Paper: Trade Policies Adopted to Address Climate Change
• World Energy Transitions Outlook: 1.5°C Pathway
• Behavioral Insights for Climate Action
• Climate Finance Shadow Report 2020: Assessing Progress Towards the $100 Billion Commitment
• Delivering on the $100 Billion Climate Finance Commitment and Transforming Climate Finance
• The Global Risks Report 2020 more... less... Report pdf: http://www3.weforum.org/docs/WEF_Global_Risk_Report_2020.pdf
• Peatland protection and restoration are key for climate change mitigation
• Social tipping dynamics for stabilizing Earth’s climate by 2050
• What is climate-smart programming and how do we achieve it?
• When Rain Turns to Dust : Understanding and Responding to the Combined Impact of Armed Conflicts and the Climate and Environment Crisis on People's Lives more... less... Find more resources from the ICRC on climate change and conflict on their dedicated page: https://www.icrc.org/en/what-we-do/climate-change-conflict
• World Heritage and Climate Change : Impacts and Adaptation
• Accelerating Climate Action : Refocusing Policies through a Well-being Lens
• Adapt Now : A Global Call for Leadership on Climate Resilience
• Climate Emergency, Urban Opportunity
• Global energy transformation: A roadmap to 2050 (2019 edition)
• Global Landscape of Climate Finance 2019
• Key Policy Issues in the Green Climate Fund: A Guide for the Perplexed
• L’essentiel: Climat et Agenda 2030
• Nature-based Solutions in Nationally Determined Contributions more... less... PDF: https://portals.iucn.org/library/sites/library/files/documents/2019-030-En.pdf
• Ocean for Climate : Ocean-related Measures in Climate Strategies (Nationally Determined Contributions, National Adaptation Plans, Adaptation Communications and National Policy Frameworks)
• World Scientists' Warning of a Climate Emergency
• The Uninhabitable Earth
• The Carbon Majors Database : CDP Carbon Majors Report 2017
• Comma but Differentiated Responsibilities: Punctuation and 30 Other Ways Negotiators Have Resolved Issues in the International Climate Change Regime

ICAT Assessment Guides

Published in November 2019 by the United Nations Office for Project Services ( UNOPS ), and prepared by the Initiative for Climate Action Transparency ( ICAT ), the Introduction to the ICAT Assessment Guides provides an overview of how to use this series of guides which help users asses the impacts of countries' climate policies and actions by providing methodologies to assess greenhouse gases, sustainable development and transformational impacts of polices and actions.

Search Library Collections

• Books & Articles
• UN Documents

List of e-journals

UN Digital Library ODS More Tools

• << Previous: Climate Change and Law / Treaties
• Next: Books & Journals >>
• Last Updated: Aug 7, 2024 2:54 PM
• URL: https://libraryresources.unog.ch/climatechange

Climate Science Special Report

Fourth national climate assessment (nca4), volume i.

This report is an authoritative assessment of the science of climate change, with a focus on the United States. It represents the first of two volumes of the Fourth National Climate Assessment, mandated by the Global Change Research Act of 1990.

USGCRP , 2017: Climate Science Special Report: Fourth National Climate Assessment, Volume I [Wuebbles, D.J., D.W. Fahey, K.A. Hibbard, D.J. Dokken, B.C. Stewart, and T.K. Maycock (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, 470 pp, doi: 10.7930/J0J964J6 .

Executive Summary

Ch. 1: Our Globally Changing Climate

Ch. 2: Physical Drivers of Climate Change

Ch. 3: Detection and Attribution of Climate Change

Ch. 4: Climate Models, Scenarios, and Projections

Ch. 5: Large-Scale Circulation and Climate Variability

Ch. 6: Temperature Changes in the United States

Ch. 7: Precipitation Change in the United States

Ch. 8: Droughts, Floods, and Wildfire

Ch. 9: Extreme Storms

Ch. 10: Changes in Land Cover and Terrestrial Biogeochemistry

Ch. 11: Arctic Changes and their Effects on Alaska and the Rest of the United States

Ch. 12: Sea Level Rise

Ch. 13: Ocean Acidification and Other Ocean Changes

Ch. 14: Perspectives on Climate Change Mitigation

Ch. 15: Potential Surprises: Compound Extremes and Tipping Elements

Appendix A: Observational Datasets Used in Climate Studies

Appendix B: Model Weighting Strategy

Appendix C: Detection and Attribution Methodologies Overview

Appendix D: Acronyms and Units

Appendix E: Glossary

An official website of the United States government

Here’s how you know

Official websites use .gov A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS A lock ( Lock Locked padlock ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

The Fifth National Climate Assessment

The Fifth National Climate Assessment is the US Government’s preeminent report on climate change impacts, risks, and responses. It is a congressionally mandated interagency effort that provides the scientific foundation to support informed decision-making across the United States.

Fifth National Climate Assessment 1. Overview Understanding Risks, Impacts, and Responses

• Addressing Climate Change
• Experiencing Climate Change
• Current and Future Risks
• Determining the Future
• A Resilient Nation

How the United States Is Addressing Climate Change

The effects of human-caused climate change are already far-reaching and worsening across every region of the United States. Rapidly reducing greenhouse gas emissions can limit future warming and associated increases in many risks. Across the country, efforts to adapt to climate change and reduce emissions have expanded since 2018, and US emissions have fallen since peaking in 2007. However, without deeper cuts in global net greenhouse gas emissions and accelerated adaptation efforts, severe climate risks to the United States will continue to grow.

Future climate change impacts depend on choices made today

The more the planet warms, the greater the impacts. Without rapid and deep reductions in global greenhouse gas emissions from human activities, the risks of accelerating sea level rise, intensifying extreme weather, and other harmful climate impacts will continue to grow. Each additional increment of warming is expected to lead to more damage and greater economic losses compared to previous increments of warming, while the risk of catastrophic or unforeseen consequences also increases. { 2.3 , 19.1 }

However, this also means that each increment of warming that the world avoids—through actions that cut emissions or remove carbon dioxide (CO 2 ) from the atmosphere—reduces the risks and harmful impacts of climate change. While there are still uncertainties about how the planet will react to rapid warming, the degree to which climate change will continue to worsen is largely in human hands. { 2.3 , 3.4 }

In addition to reducing risks to future generations, rapid emissions cuts are expected to have immediate health and economic benefits (Figure 1.1 ). At the national scale, the benefits of deep emissions cuts for current and future generations are expected to far outweigh the costs. { 2.1 , 2.3 , 13.3 , 14.5 , 15.3 , 32.4 ; Ch. 2, Introduction }

US emissions have decreased, while the economy and population have grown

Annual US greenhouse gas emissions fell 12% between 2005 and 2019. This trend was largely driven by changes in electricity generation: coal use has declined, while the use of natural gas and renewable technologies has increased, leading to a 40% drop in emissions from the electricity sector. Since 2017, the transportation sector has overtaken electricity generation as the largest emitter. { 11.1 , 13.1 , 32.1 ; Figures 32.1 , 32.3 }

As US emissions have declined from their peak in 2007, the country has also seen sustained reductions in the amount of energy required for a given quantity of economic activity and the emissions produced per unit of energy consumed. Meanwhile, both population and per capita GDP have continued to grow. { 32.1 ; Figures 32.1 , 32.2 }

Recent growth in the capacities of wind, solar, and battery storage technologies is supported by rapidly falling costs of zero- and low-carbon energy technologies, which can support even deeper emissions reductions. For example, wind and solar energy costs dropped 70% and 90%, respectively, over the last decade, while 80% of new generation capacity in 2020 came from renewable sources (Figures 1.2 , 1.3 ). { 5.3 , 12.3 , 32.1 , 32.2 ; Figure A4.17 }

Across all sectors, innovation is expanding options for reducing energy demand and increasing energy efficiency, moving to zero- and low-carbon electricity and fuels, electrifying energy use in buildings and transportation, and adopting practices that protect and improve natural carbon sinks that remove and store CO 2 from the atmosphere, such as sustainable agricultural and land-management practices. { 11.1 , 32.2 , 32.3 ; Boxes 32.1 , 32.2 ; Focus on Blue Carbon }

Accelerating advances in adaptation can help reduce rising climate risks

As more people face more severe climate impacts, individuals, organizations, companies, communities, and governments are taking advantage of adaptation opportunities that reduce risks. State climate assessments and online climate services portals are providing communities with location- and sector-specific information on climate hazards to support adaptation planning and implementation across the country. New tools, more data, advancements in social and behavioral sciences, and better consideration of practical experiences are facilitating a range of actions (Figure 1.3 ). { 7.3 , 12.3 , 21.4 , 25.4 , 31.1 , 31.5 , 32.5 ; Table 31.1 }

Actions include:

Implementing nature-based solutions—such as restoring coastal wetlands or oyster reefs—to reduce shoreline erosion { 8.3 , 9.3 , 21.2 , 23.5 }

Upgrading stormwater infrastructure to account for heavier rainfall { 4.2 }

Applying innovative agricultural practices to manage increasing drought risk { 11.1 , 22.4 , 25.5 }

Assessing climate risks to roads and public transit { 13.1 }

Managing vegetation to reduce wildfire risk { 5.3 }

Developing urban heat plans to reduce health risks from extreme heat { 12.3 , 21.1 , 28.4 }

Planning relocation from high-risk coastal areas { 9.3 }

Despite an increase in adaptation actions across the country, current adaptation efforts and investments are insufficient to reduce today’s climate-related risks and keep pace with future changes in the climate. Accelerating current efforts and implementing new ones that involve more fundamental shifts in systems and practices can help address current risks and prepare for future impacts (see “Mitigation and adaptation actions can result in systemic, cascading benefits” below). { 31.1 , 31.3 }

Climate action has increased in every region of the US

Efforts to adapt to climate change and reduce net greenhouse gas emissions are underway in every US region and have expanded since 2018 (Figure 1.3 ; Table 1.1 ). Many actions can achieve both adaptation and mitigation goals. For example, improved forest- or land-management strategies can both increase carbon storage and protect ecosystems, and expanding renewable energy options can reduce emissions while also improving resilience. { 31.1 , 32.5 }

Climate adaptation and mitigation efforts involve trade-offs, as climate actions that benefit some or even most people can result in burdens to others. To date, some communities have prioritized equitable and inclusive planning processes that consider the social impacts of these trade-offs and help ensure that affected communities can participate in decision-making. As additional measures are implemented, more widespread consideration of their social impact can help inform decisions around how to distribute the outcomes of investments. { 12.4 , 13.4 , 20.2 , 21.3 , 21.4 , 26.4 , 27.1 , 31.2 , 32.4 , 32.5 ; Box 20.1 }

Meeting US mitigation targets means reaching net-zero emissions

The global warming observed over the industrial era is unequivocally caused by greenhouse gas emissions from human activities—primarily burning fossil fuels. Atmospheric concentrations of carbon dioxide (CO 2 )—the primary greenhouse gas produced by human activities—and other greenhouse gases continue to rise due to ongoing global emissions. Stopping global warming would require both reducing emissions of CO 2 to net zero and rapid and deep reductions in other greenhouse gases. Net-zero CO 2 emissions means that CO 2 emissions decline to zero or that any residual emissions are balanced by removal from the atmosphere. { 2.3 , 3.1 ; Ch. 32 }

Once CO 2 emissions reach net zero, the global warming driven by CO 2 is expected to stop: additional warming over the next few centuries is not necessarily “locked in” after net CO 2 emissions fall to zero. However, global average temperatures are not expected to fall for centuries unless CO 2 emissions become net negative, which is when CO 2 removal from the atmosphere exceeds CO 2 emissions from human activities. Regardless of when or if further warming is avoided, some long-term responses to the temperature changes that have already occurred will continue. These responses include sea level rise, ice sheet losses, and associated disruptions to human health, social systems, and ecosystems. In addition, the ocean will continue to acidify after the world reaches net-zero CO 2 emissions, as it continues to gradually absorb CO 2 in the atmosphere from past emissions. { 2.1 , 2.3 , 3.1 ; Ch. 2, Introduction }

National and international commitments seek to limit global warming to well below 2°C (3.6°F), and preferably to 1.5°C (2.7°F), compared to preindustrial temperature conditions (defined as the 1850–1900 average). To achieve this, global CO 2 emissions would have to reach net zero by around 2050 (Figure 1.4 ); global emissions of all greenhouse gases would then have to reach net zero within the following few decades. { 2.3 , 32.1 }

While US greenhouse gas emissions are falling, the current rate of decline is not sufficient to meet national and international climate commitments and goals. US net greenhouse gas emissions remain substantial and would have to decline by more than 6% per year on average, reaching net-zero emissions around midcentury, to meet current national mitigation targets and international temperature goals; by comparison, US greenhouse gas emissions decreased by less than 1% per year on average between 2005 and 2019. { 32.1 }

Many cost-effective options that are feasible now have the potential to substantially reduce emissions over the next decade. Faster and more widespread deployment of renewable energy and other zero- and low-carbon energy options can accelerate the transition to a decarbonized economy and increase the chances of meeting a 2050 national net-zero greenhouse gas emissions target for the US. However, to reach the US net-zero emissions target, additional mitigation options need to be explored and advanced (see “Available mitigation strategies can deliver substantial emissions reductions, but additional options are needed to reach net zero” below). { 5.3 , 6.3 , 32.2 , 32.3 }

Jay, A.K., A.R. Crimmins, C.W. Avery, T.A. Dahl, R.S. Dodder, B.D. Hamlington, A. Lustig, K. Marvel, P.A. Méndez-Lazaro, M.S. Osler, A. Terando, E.S. Weeks, and A. Zycherman, 2023: Ch. 1. Overview: Understanding risks, impacts, and responses. In: Fifth National Climate Assessment . Crimmins, A.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, B.C. Stewart, and T.K. Maycock, Eds. U.S. Global Change Research Program, Washington, DC, USA. https://doi.org/10.7930/NCA5.2023.CH1

Download citation: BibTeX     |     RIS

How the United States Is Experiencing Climate Change

As extreme events and other climate hazards intensify, harmful impacts on people across the United States are increasing. Climate impacts—combined with other stressors—are leading to ripple effects across sectors and regions that multiply harms, with disproportionate effects on underserved and overburdened communities.

Current climate changes are unprecedented over thousands of years

Global greenhouse gas emissions from human activities continue to increase, resulting in rapid warming (Figure 1.5 ) and other large-scale changes, including rising sea levels, melting ice, ocean warming and acidification, changing rainfall patterns, and shifts in timing of seasonal events. Many of the climate conditions and impacts people are experiencing today are unprecedented for thousands of years (Figure 1.6 ). { 2.1 , 3.1 ; Figures A4.6 , A4.7 , A4.10 , A4.13 }

As the world’s climate has shifted toward warmer conditions, the frequency and intensity of extreme cold events have declined over much of the US, while the frequency, intensity, and duration of extreme heat have increased. Across all regions of the US, people are experiencing warming temperatures and longer-lasting heatwaves. Over much of the country, nighttime temperatures and winter temperatures have warmed more rapidly than daytime and summer temperatures. Many other extremes, including heavy precipitation, drought, flooding, wildfire, and hurricanes, are becoming more frequent and/or severe, with a cascade of effects in every part of the country. { 2.1 , 2.2 , 3.4 , 4.1 , 4.2 , 7.1 , 9.1 ; Ch. 2, Introduction ; App. 4 ; Focus on Compound Events }

Risks from extreme events are increasing

One of the most direct ways that people experience climate change is through changes in extreme events. Harmful impacts from more frequent and severe extremes are increasing across the country—including increases in heat-related illnesses and death, costlier storm damages, longer droughts that reduce agricultural productivity and strain water systems, and larger, more severe wildfires that threaten homes and degrade air quality. { 2.2 , 4.2 , 12.2 , 14.2 , 15.1 , 19.2 ; Focus on Western Wildfires }

Extreme weather events cause direct economic losses through infrastructure damage, disruptions in labor and public services, and losses in property values. The number and cost of weather-related disasters have increased dramatically over the past four decades, in part due to the increasing frequency and intensity of extreme events and in part due to increases in assets at risk (through population growth, rising property values, and continued development in hazard-prone areas). Low-income communities, communities of color, and Tribes and Indigenous Peoples experience high exposure and vulnerability to extreme events due to both their proximity to hazard-prone areas and lack of adequate infrastructure or disaster management resources. { 2.2 , 4.2 , 17.3 , 19.1 ; Focus on Compound Events }

In the 1980s, the country experienced, on average, one (inflation-adjusted) billion-dollar disaster every four months. Now, there is one every three weeks, on average. Between 2018 and 2022, the US experienced 89 billion-dollar events (Figure 1.7 ). Extreme events cost the US close to $150 billion each year—a conservative estimate that does not account for loss of life, healthcare-related costs, or damages to ecosystem services. { 2.2 , 19.1 ; Ch. 2, Introduction ; Figures 4.1 , A4.5 }

Cascading and compounding impacts increase risks

The impacts and risks of climate change unfold across interacting sectors and regions. For example, wildfire in one region can affect air quality and human health in other regions, depending on where winds transport smoke. Further, climate change impacts interact with other stressors, such as the COVID-19 pandemic, environmental degradation, or socioeconomic stressors like poverty and lack of adequate housing that disproportionately impact overburdened communities. These interactions and interdependencies can lead to cascading impacts and sudden failures. For example, climate-related shocks to the food supply chain have led to local to global impacts on food security and human migration patterns that affect US economic and national security interests. { 11.3 , 17.1 , 17.2 , 17.3 , 18.1 , 22.3 , 23.4 , 31.3 ; Introductions in Chs. 2 , 17 , 18 ; Focus on Compound Events ; Focus on Risks to Supply Chains ; Focus on COVID-19 and Climate Change }

The risk of two or more extreme events occurring simultaneously or in quick succession in the same region—known as compound events—is increasing. Climate change is also increasing the risk of multiple extremes occurring simultaneously in different locations that are connected by complex human and natural systems. For instance, simultaneous megafires across multiple western states and record back-to-back Atlantic hurricanes in 2020 caused unprecedented demand on federal emergency response resources. { 2.2 , 3.2 , 15.1 , 22.2 , 26.4 ; Focus on Compound Events ; Ch. 4, Introduction }

Compound events often have cascading impacts that cause greater harm than individual events. For example, in 2020, record-breaking heat and widespread drought contributed to concurrent destructive wildfires across California, Oregon, and Washington, exposing millions to health hazards and straining firefighting resources. Ongoing drought amplified the record-breaking Pacific Northwest heatwave of June 2021, which was made 2° to 4°F hotter by climate change. The heatwave led to more than 1,400 heat-related deaths, another severe wildfire season, mass die-offs of fishery species important to the region’s economy and Indigenous communities, and total damages exceeding $38.5 billion (in 2022 dollars). { 27.3 ; Ch. 2, Introduction ; Focus on Compound Events , Focus on Western Wildfires }

Climate change exacerbates inequities

Some communities are at higher risk of negative impacts from climate change due to social and economic inequities caused by ongoing systemic discrimination, exclusion, and under- or disinvestment. Many such communities are also already overburdened by the cumulative effects of adverse environmental, health, economic, or social conditions. Climate change worsens these long-standing inequities, contributing to persistent disparities in the resources needed to prepare for, respond to, and recover from climate impacts. { 4.2 , 9.2 , 12.2 , 14.3 , 15.2 , 16.1 , 16.2 , 18.2 , 19.1 , 20.1 , 20.3 , 21.3 , 22.1 , 23.1 , 26.4 , 27.1 , 31.2 }

For example, low-income communities and communities of color often lack access to adequate flood infrastructure, green spaces, safe housing, and other resources that help protect people from climate impacts. In some areas, patterns of urban growth have led to the displacement of under-resourced communities to suburban and rural areas with less access to climate-ready housing and infrastructure. Extreme heat can lead to higher rates of illness and death in low-income neighborhoods, which are hotter on average (Figure 1.8 ). Neighborhoods that are home to racial minorities and low-income people have the highest inland (riverine) flood exposures in the South, and Black communities nationwide are expected to bear a disproportionate share of future flood damages—both coastal and inland (Figure 1.9 ). { 4.2 , 11.3 , 12.2 , 15.1 , 22.1 , 22.2 , 26.4 , 27.1 ; Ch. 2, Introduction }

These disproportionate impacts are partly due to exclusionary housing practices—both past and ongoing—that leave underserved communities with less access to heat and flood risk-reduction strategies and other economic, health, and social resources. For example, areas that were historically redlined—a practice in which lenders avoided providing services to communities, often based on their racial or ethnic makeup—continue to be deprived of equitable access to environmental amenities like urban green spaces that reduce exposure to climate impacts. These neighborhoods can be as much as 12°F hotter during a heatwave than nearby wealthier neighborhoods. { 8.3 , 9.2 , 12.2 , 15.2 , 20.3 , 21.3 , 22.1 , 26.4 , 27.1 , 32.4 ; Ch. 2, Introduction }

Harmful impacts will increase in the near term

Even if greenhouse gas emissions fall substantially, the impacts of climate change will continue to intensify over the next decade (see “Meeting US mitigation targets means reaching net-zero emissions” above; Box 1.4 ), and all US regions are already experiencing increasingly harmful impacts. Although a few US regions or sectors may experience limited or short-term benefits from climate change, adverse impacts already far outweigh any positive effects and will increasingly eclipse benefits with additional warming. { 2.3 , 19.1 ; Ch. 2, Introduction ; Chs. 21–30}

Table 1.2 shows examples of critical impacts expected to affect people in each region between now and 2030, with disproportionate effects on overburdened communities. While these examples affect particular regions in the near term, impacts often cascade through social and ecological systems and across borders and may lead to longer-term losses. { 15.2 , 18.2 , 20.1 ; Figure 15.5 ; Ch. 20, Introduction }

Current and Future Climate Risks to the United States

Climate changes are making it harder to maintain safe homes and healthy families; reliable public services; a sustainable economy; thriving ecosystems, cultures, and traditions; and strong communities. Many of the extreme events and harmful impacts that people are already experiencing will worsen as warming increases and new risks emerge.

Safe, reliable water supplies are threatened by flooding, drought, and sea level rise

More frequent and intense heavy precipitation events are already evident, particularly in the Northeast and Midwest. Urban and agricultural environments are especially vulnerable to runoff and flooding. Between 1981 and 2016, US corn yield losses from flooding were comparable to those from extreme drought. Runoff and flooding also transport debris and contaminants that cause harmful algal blooms and pollute drinking water supplies. Communities of color and low-income communities face disproportionate flood risks. { 2.2 , 4.2 , 6.1 , 9.2 , 21.3 , 24.1 , 24.5 , 26.4 ; Figure A4.8 }

Between 1980 and 2022, drought and related heatwaves caused approximately $328 billion in damages (in 2022 dollars). Recent droughts have strained surface water and groundwater supplies, reduced agricultural productivity, and lowered water levels in major reservoirs, threatening hydropower generation. As higher temperatures increase irrigation demand, increased pumping could endanger groundwater supplies, which are already declining in many major aquifers. { 4.1, 4.2 ; Figure A4.9 }

Droughts are projected to increase in intensity, duration, and frequency, especially in the Southwest, with implications for surface water and groundwater supplies. Human and natural systems are threatened by rapid shifts between wet and dry periods that make water resources difficult to predict and manage. { 2.2 , 2.3 , 4.1 , 4.2 , 5.1 , 28.1 }

In coastal environments, dry conditions, sea level rise, and saltwater intrusion endanger groundwater aquifers and stress aquatic ecosystems. Inland, decreasing snowpack alters the volume and timing of streamflow and increases wildfire risk. Small rural water providers that often depend on a single water source or have limited capacity are especially vulnerable. { 4.2 , 7.2 , 9.2 , 21.2 , 22.1 , 23.1 , 23.3 , 25.1 , 27.4 , 28.1 , 28.2 , 28.5 , 30.1 ; Figure A4.7 }

Many options are available to protect water supplies, including reservoir optimization, nature-based solutions, and municipal management systems to conserve and reuse water. Collaboration on flood hazard management at regional scales is particularly important in areas where flood risk is increasing, as cooperation can provide solutions unavailable at local scales. { 4.3 , 9.3 , 26.5 ; Focus on Blue Carbon }

Disruptions to food systems are expected to increase

As the climate changes, increased instabilities in US and global food production and distribution systems are projected to make food less available and more expensive. These price increases and disruptions are expected to disproportionately affect the nutrition and health of women, children, older adults, and low-wealth communities. { 11.2 , 15.2 }

Climate change also disproportionately harms the livelihoods and health of communities that depend on agriculture, fishing, and subsistence lifestyles, including Indigenous Peoples reliant on traditional food sources. Heat-related stress and death are significantly greater for farmworkers than for all US civilian workers. { 11.2 , 11.3 , 15.1 , 15.2 , 16.1 ; Focus on Risks to Supply Chains }

While farmers, ranchers, and fishers have always faced unpredictable weather, climate change heightens risks in many ways:

Increasing temperatures, along with changes in precipitation, reduce productivity, yield, and nutritional content of many crops. These changes can introduce disease, disrupt pollination, and result in crop failure, outweighing potential benefits of longer growing seasons and increased CO 2 fertilization. { 11.1 , 19.1 , 21.1 , 22.4 , 23.3 , 24.1 , 26.2 }

Heavy rain and more frequent storms damage crops and property and contaminate water supplies. Longer-lasting droughts and larger wildfires reduce forage production and nutritional quality, diminish water supplies, and increase heat stress on livestock. { 23.2, 25.3 , 28.3 }

Increasing water temperatures, invasive aquatic species, harmful algal blooms, and ocean acidification and deoxygenation put fisheries at risk. Fishery collapses can result in large economic losses, as well as loss of cultural identity and ways of life. { 11.3 , 29.3 }

In response, some farmers and ranchers are adopting innovations—such as agroecological practices, data-driven precision agriculture, and carbon monitoring—to improve resilience, enhance soil carbon storage, and reduce emissions. Across the Nation, Indigenous food security efforts are helping improve community resilience to climate change while also improving cultural resilience. Some types of aquaculture have the potential to increase climate-smart protein production, human nutrition, and food security, although some communities have raised concerns over issues such as conflict with traditional livelihoods and the introduction of disease or pollution. { 10.2 , 11.1 , 29.6 , 25.5 ; Boxes 22.3 , 27.2 }

Homes and property are at risk from sea level rise and more intense extreme events

Homes, property, and critical infrastructure are increasingly exposed to more frequent and intense extreme events, increasing the cost of maintaining a safe and healthy place to live. Development in fire-prone areas and increases in area burned by wildfires have heightened risks of loss of life and property damage in many areas across the US. Coastal communities across the country—home to 123 million people (40% of the total US population)—are exposed to sea level rise (Figure 1.10 ), with millions of people at risk of being displaced from their homes by the end of the century. { 2.3 , 9.1 , 12.2 , 22.1 , 27.4 , 30.3 ; Figures A4.10 , A4.14 ; Focus on Western Wildfires }

People who regularly struggle to afford energy bills—such as rural, low-income, and older fixed-income households and communities of color—are especially vulnerable to more intense extreme heat events and associated health risks, particularly if they live in homes with poor insulation and inefficient cooling systems. For example, Black Americans are more likely to live in older, less energy efficient homes and face disproportionate heat-related health risks. { 5.2 , 15.2 , 15.3 , 22.2 , 26.4 , 32.4 ; Figure A4.4 }

Accessible public cooling centers can help protect people who lack adequate air-conditioning on hot days. Strategic land-use planning in cities, urban greenery, climate-smart building codes, and early warning communication can also help neighborhoods adapt. However, other options at the household scale, such as hardening homes against weather extremes or relocation, may be out of reach for renters and low-income households without assistance. { 12.3 , 15.3 , 19.3 , 22.2 }

Infrastructure and services are increasingly damaged and disrupted by extreme weather and sea level rise

Climate change threatens vital infrastructure that moves people and goods, powers homes and businesses, and delivers public services. Many infrastructure systems across the country are at the end of their intended useful life and are not designed to cope with additional stress from climate change. For example, extreme heat causes railways to buckle, severe storms overload drainage systems, and wildfires result in roadway obstruction and debris flows. Risks to energy, water, healthcare, transportation, telecommunications, and waste management systems will continue to rise with further climate change, with many infrastructure systems at risk of failing. { 12.2 , 13.1 , 15.2 , 23.4 , 26.5 ; Focus on Risks to Supply Chains }

In coastal areas, sea level rise threatens permanent inundation of infrastructure, including roadways, railways, ports, tunnels, and bridges; water treatment facilities and power plants; and hospitals, schools, and military bases. More intense storms also disrupt critical services like access to medical care, as seen after Hurricanes Irma and Maria in the US Virgin Islands and Puerto Rico. { 9.2 , 23.1 , 28.2 , 30.3 }

At the same time, climate change is expected to place multiple demands on infrastructure and public services. For example, higher temperatures and other effects of climate change, such as greater exposure to stormwater or wastewater, will increase demand for healthcare. Continued increases in average temperatures and more intense heatwaves will heighten electricity and water demand, while wetter storms and intensified hurricanes will strain wastewater and stormwater management systems. In the Midwest and other regions, aging energy grids are expected to be strained by disruptions and transmission efficiency losses from climate change. { 23.4 , 24.4 , 30.2 }

Forward-looking designs of infrastructure and services can help build resilience to climate change, offset costs from future damage to transportation and electrical systems, and provide other benefits, including meeting evolving standards to protect public health, safety, and welfare. Mitigation and adaptation activities are advancing from planning stages to deployment in many areas, including improved grid design and workforce training for electrification, building upgrades, and land-use choices. Grid managers are gaining experience planning and operating electricity systems with growing shares of renewable generation and working toward understanding the best approaches for dealing with the natural variability of wind and solar sources alongside increases in electrification. { 5.3 , 12.3 , 13.1 , 13.2 , 22.3 , 24.4 , 32.3 ; Figure 22.17 }

Climate change exacerbates existing health challenges and creates new ones

Climate change is already harming human health across the US, and impacts are expected to worsen with continued warming. Climate change harms individuals and communities by exposing them to a range of compounding health hazards, including the following:

More severe and frequent extreme events { 2.2 , 2.3 , 15.1 }

Wider distribution of infectious and vector-borne pathogens { 15.1 , 26.1 ; Figure A4.16 }

Air quality worsened by smog, wildfire smoke, dust, and increased pollen { 14.1 , 14.2 , 14.4 , 23.1 , 26.1 }

Threats to food and water security { 11.2 , 15.1 }

Mental and spiritual health stressors { 15.1 }

While climate change can harm everyone’s health, its impacts exacerbate long-standing disparities that result in inequitable health outcomes for historically marginalized people, including people of color, Indigenous Peoples, low-income communities, and sexual and gender minorities, as well as older adults, people with disabilities or chronic diseases, outdoor workers, and children. { 14.3 , 15.2 }

The disproportionate health impacts of climate change compound with similar disparities in other health contexts. For example, climate-related disasters during the COVID-19 pandemic, such as drought along the Colorado River basin, western wildfires, and Hurricane Laura, disproportionately magnified COVID-19 exposure, transmission, and disease severity and contributed to worsened health conditions for essential workers, older adults, farmworkers, low-wealth communities, and communities of color. { 15.2 ; Focus on COVID-19 and Climate Change }

Large reductions in greenhouse gas emissions are expected to result in widespread health benefits and avoided death or illness that far outweigh the costs of mitigation actions. Improving early warning, surveillance, and communication of health threats; strengthening the resilience of healthcare systems; and supporting community-driven adaptation strategies can reduce inequities in the resources and capabilities needed to adapt as health threats from climate change continue to grow. { 14.5 , 15.3 , 26.1 , 30.2 , 32.4 }

Ecosystems are undergoing transformational changes

Together with other stressors, climate change is harming the health and resilience of ecosystems, leading to reductions in biodiversity and ecosystem services. Increasing temperatures continue to shift habitat ranges as species expand into new regions or disappear from unfavorable areas, altering where people can hunt, catch, or gather economically important and traditional food sources. Degradation and extinction of local flora and fauna in vulnerable ecosystems like coral reefs and montane rainforests are expected in the near term, especially where climate changes favor invasive species or increase susceptibility to pests and pathogens. Without significant emissions reductions, rapid shifts in environmental conditions are expected to lead to irreversible ecological transformations by mid- to late century. { 2.3 , 6.2 , 7.1 , 7.2 , 8.1 , 8.2 , 10.1 , 10.2 , 21.1 , 24.2 , 27.2 , 28.5 , 29.3 , 29.5 , 30.4 ; Figure A4.12 }

Changes in ocean conditions and extreme events are already transforming coastal, aquatic, and marine ecosystems. Coral reefs are being lost due to warming and ocean acidification, harming important fisheries; coastal forests are converting to ghost forests, shrublands, and marsh due to sea level rise, reducing coastal protection; lake and stream habitats are being degraded by warming, heavy rainfall, and invasive species, leading to declines in economically important species. { 8.1 , 10.1 , 21.2 , 23.2 , 24.2 , 27.2 ; Figures 8.7 , A4.11 }

Increased risks to ecosystems are expected with further climate change and other environmental changes, such as habitat fragmentation, pollution, and overfishing. For example, mass fish die-offs from extreme summertime heat are projected to double by midcentury in northern temperate lakes under a very high scenario (RCP8.5). Continued climate changes are projected to exacerbate runoff and erosion, promote harmful algal blooms, and expand the range of invasive species. { 4.2 , 7.1 , 8.2 , 10.1 , 21.2 , 23.2 , 24.2 , 27.2 , 28.2 , 30.4 }

While adaptation options to protect fragile ecosystems may be limited, particularly under higher levels of warming, management and restoration measures can reduce stress on ecological systems and build resilience. These measures include migration assistance for vulnerable species and protection of essential habitats, such as establishing wildlife corridors or places where species can avoid heat. Opportunities for nature-based solutions that assist in mitigation exist across the US, particularly those focused on protecting existing carbon sinks and increasing carbon storage by natural ecosystems. { 8.3 , 10.3 , 23.2 , 27.2 ; Focus on Blue Carbon }

Climate change slows economic growth, while climate action presents opportunities

With every additional increment of global warming, costly damages are expected to accelerate. For example, 2°F of warming is projected to cause more than twice the economic harm induced by 1°F of warming. Damages from additional warming pose significant risks to the US economy at multiple scales and can compound to dampen economic growth. { 19.1 }

International impacts can disrupt trade, amplify costs along global supply chains, and affect domestic markets. { 17.3 , 19.2 ; Focus on Risks to Supply Chains }

While some economic impacts of climate change are already being felt across the country, the impacts of future changes are projected to be more significant and apparent across the US economy. { 19.1 }

States, cities, and municipalities confront climate-driven pressures on public budgets and borrowing costs amid spending increases on healthcare and disaster relief. { 19.2 }

Household consumers face higher costs for goods and services, like groceries and health insurance premiums, as prices change to reflect both current and projected climate-related damages. { 19.2 }

Mitigation and adaptation actions present economic opportunities. Public and private measures—such as climate financial risk disclosures, carbon offset credit markets, and investments in green bonds—can avoid economic losses and improve property values, resilience, and equity. However, climate responses are not without risk. As innovation and trade open further investment opportunities in renewable energy and the country continues to transition away from fossil fuels, loss and disposal costs of stranded capital assets such as coal mines, oil and gas wells, and outdated power plants are expected. Climate solutions designed without input from affected communities can also result in increased vulnerability and cost burden. { 17.3 , 19.2 , 19.3 , 20.2 , 20.3 , 27.1 , 31.6 }

Many regional economies and livelihoods are threatened by damages to natural resources and intensifying extremes

Climate change is projected to reduce US economic output and labor productivity across many sectors, with effects differing based on local climate and the industries unique to each region. Climate-driven damages to local economies especially disrupt heritage industries (e.g., fishing traditions, trades passed down over generations, and cultural heritage–based tourism) and communities whose livelihoods depend on natural resources. { 11.3 , 19.1 , 19.3 }

As fish stocks in the Northeast move northward and to deeper waters in response to rapidly rising ocean temperatures, important fisheries like scallops, shrimp, and cod are at risk. In Alaska, climate change has already played a role in 18 major fishery disasters that were especially damaging for coastal Indigenous Peoples, subsistence fishers, and rural communities. { 10.2 , 21.2 , 29.3 }

While the Southeast and US Caribbean face high costs from projected labor losses and heat health risks to outdoor workers, small businesses are already confronting higher costs of goods and services and potential closures as they struggle to recover from the effects of compounding extreme weather events. { 22.3 , 23.1 }

Agricultural losses in the Midwest, including lower corn yields and damages to specialty crops like apples, are linked to rapid shifts between wet and dry conditions and stresses from climate-induced increases in pests and pathogens. Extreme heat and more intense wildfire and drought in the Southwest are already threatening agricultural worker health, reducing cattle production, and damaging wineries. { 24.1 , 28.5 }

In the Northern Great Plains, agriculture and recreation are expected to see primarily negative effects related to changing temperature and rainfall patterns. By 2070, the Southern Great Plains is expected to lose cropland acreage as lands transition to pasture or grassland. { 25.3 , 26.2 }

Outdoor-dependent industries, such as tourism in Hawai‘i and the US-Affiliated Pacific Islands and skiing in the Northwest, face significant economic loss from projected rises in park closures and reductions in workforce as continued warming leads to deterioration of coastal ecosystems and shorter winter seasons with less snowfall. { 7.2 , 8.3 , 10.1 , 10.3 , 19.1 , 27.3 , 30.4 }

Mitigation and adaptation actions taken by businesses and industries promote resilience and offer long-term benefits to employers, employees, and surrounding communities. For example, as commercial fisheries adapt, diversifying harvest and livelihoods can help stabilize income or buffer risk. In addition, regulators and investors are increasingly requiring businesses to disclose climate risks and management strategies. { 10.2 , 19.3 , 26.2 }

Job opportunities are shifting due to climate change and climate action

Many US households are already feeling the economic impacts of climate change. Climate change is projected to impose a variety of new or higher costs on most households as healthcare, food, insurance, building, and repair costs become more expensive. Compounding climate stressors can increase segregation, income inequality, and reliance on social safety net programs. Quality of life is also threatened by climate change in ways that can be more difficult to quantify, such as increased crime and domestic violence, harm to mental health, reduced happiness, and fewer opportunities for outdoor recreation and play. { 11.3 , 19.1, 19.3 }

Climate change, and how the country responds, is expected to alter demand for workers and shift where jobs are available. For example, energy-related livelihoods in the Northern and Southern Great Plains are expected to shift as the energy sector transforms toward more renewables, low-carbon technologies, and electrification of more sectors of the economy. Losses in fossil fuel–related jobs are projected to be completely offset by greater increases in mitigation-related jobs, as increased demand for renewable energy and low-carbon technologies is expected to lead to long-term expansion in most states’ energy and decarbonization workforce (Figure 1.12 ). Grid expansion and energy efficiency efforts are already creating new jobs in places like Nevada, Vermont, and Alaska, and advancements in biofuels and agrivoltaics (combined renewable energy and agriculture) provide economic opportunities in rural communities. { 10.2 , 11.3 , 19.3 , 25.3 , 26.2 , 29.3 , 32.4 }

Additional opportunities include jobs in ecosystem restoration and construction of energy-efficient and climate-resilient housing and infrastructure. Workforce training and equitable access to clean energy jobs, which have tended to exclude women and people of color, are essential elements of a just transition to a decarbonized economy. { 5.3 , 19.3 , 20.3 , 22.3 , 25.3 , 26.2 , 27.3 , 32.4 }

Climate change is disrupting cultures, heritages, and traditions

As climate change transforms US landscapes and ecosystems, many deeply rooted community ties, pastimes, Traditional Knowledges, and cultural or spiritual connections to place are at risk. Cultural heritage—including buildings, monuments, livelihoods, and practices—is threatened by impacts on natural ecosystems and the built environment. Damages to archaeological, cultural, and historical sites further reduce opportunities to transfer important knowledge and identity to future generations. { 6.1 , 7.2 , 8.3 , 9.2 , 10.1 , 12.2 , 16.1 , 22.1 , 23.1 , 26.1 , 27.6 , 28.2 ; Introductions in Chs. 10 , 30 }

Many outdoor activities and traditions are already being affected by climate change, with overall impacts projected to further hinder recreation, cultural practices, and the ability of communities to maintain local heritage and a sense of place. { 19.1 }

For example:

The prevalence of invasive species and harmful algal blooms is increasing as waters warm, threatening activities like swimming along Southeast beaches, boating and fishing for walleye in the Great Lakes, and viewing whooping cranes along the Gulf Coast. In the Northwest, water-based recreation demand is expected to increase in spring and summer months, but reduced water quality and harmful algal blooms are expected to restrict these opportunities. { 24.2 , 24.5 , 26.3 , 27.6 }

Ranges of culturally important species are shifting as temperatures warm, making them harder to find in areas where Indigenous Peoples have access (see Box 1.3 ). { 11.2 , 24.2 , 26.1 }

Hikers, campers, athletes, and spectators face increasing threats from more severe heatwaves, wildfires, and floods and greater exposure to infectious disease. { 22.2 , 15.1 , 26.3 , 27.6 }

Nature-based solutions and ecosystem restoration can preserve cultural heritage while also providing valuable local benefits, such as flood protection and new recreational opportunities. Cultural heritage can also play a key role in climate solutions, as incorporating local values, Indigenous Knowledge, and equity into design and planning can help reaffirm a community’s connection to place, strengthen social networks, and build new traditions. { 7.3 , 26.1 , 26.3 , 30.5 }

The Choices That Will Determine the Future

With each additional increment of warming, the consequences of climate change increase. The faster and further the world cuts greenhouse gas emissions, the more future warming will be avoided, increasing the chances of limiting or avoiding harmful impacts to current and future generations.

Societal choices drive greenhouse gas emissions

The choices people make on a day-to-day basis—how to power homes and businesses, get around, and produce and use food and other goods—collectively determine the amount of greenhouse gases emitted. Human use of fossil fuels for transportation and energy generation, along with activities like manufacturing and agriculture, has increased atmospheric levels of carbon dioxide (CO 2 ) and other heat-trapping greenhouse gases. Since 1850, CO 2 concentrations have increased by almost 50%, methane by more than 156%, and nitrous oxide by 23%, resulting in long-term global warming. { 2.1 , 3.1 ; Ch. 2, Introduction }

The CO 2 not removed from the atmosphere by natural sinks lingers for thousands of years. This means that CO 2 emitted long ago continues to contribute to climate change today. Because of historical trends, cumulative CO 2 emissions from fossil fuels and industry in the US are higher than from any other country. To understand the total contributions of past actions to observed climate change, additional warming from CO 2 emissions from land use, land-use change, and forestry, as well as emissions of nitrous oxide and the shorter-lived greenhouse gas methane, should also be taken into account. Accounting for all of these factors and emissions from 1850–2021, emissions from the US are estimated to comprise approximately 17% of current global warming. { 2.1 }

Carbon dioxide, along with other greenhouse gases like methane and nitrous oxide, is well-mixed in the atmosphere. This means these gases warm the planet regardless of where they were emitted. For the first half of the 20th century, the vast majority of greenhouse gas emissions came from the US and Europe. But as US and European emissions have been falling (US emissions in 2021 were 17% lower than 2005 levels), emissions from the rest of the world, particularly Asia, have been rising rapidly. The choices the US and other countries make now will determine the trajectory of climate change and associated impacts for many generations to come (Figure 1.13 ). { 2.1 , 2.3 ; Ch. 32 }

Rising global emissions are driving global warming, with faster warming in the US

The observed global warming of about 2°F (1.1°C) over the industrial era is unequivocally caused by greenhouse gas emissions from human activities, with only very small effects from natural sources. About three-quarters of total emissions and warming (1.7°F [0.95°C]) have occurred since 1970. Warming would have been even greater without the land and ocean carbon sinks, which have absorbed more than half of the CO 2 emitted by humans. { 2.1 , 3.1 , 7.2 ; Ch. 2, Introduction ; Figures 3.1 , 3.8 }

The US is warming faster than the global average, reflecting a broader global pattern: land areas are warming faster than the ocean, and higher latitudes are warming faster than lower latitudes. Additional global warming is expected to lead to even greater warming in some US regions, particularly Alaska (Figure 1.14 ). { 2.1 , 3.4 ; Ch. 2, Introduction ; App. 4 }

Warming increases risks to the US

Rising temperatures lead to many large-scale changes in Earth’s climate system, and the consequences increase with warming (Figure 1.15 ). Some of these changes can be further amplified through feedback processes at higher levels of warming, increasing the risk of potentially catastrophic outcomes. For example, uncertainty in the stability of ice sheets at high warming levels means that increases in sea level along the continental US of 3–7 feet by 2100 and 5–12 feet by 2150 are distinct possibilities that cannot be ruled out. The chance of reaching the upper end of these ranges increases as more warming occurs. In addition to warming more, the Earth warms faster in high and very high scenarios (SSP3-7.0 and SSP5-8.5, respectively), making adaptation more challenging. { 2.3 , 3.1 , 3.4 , 9.1 }

How Climate Action Can Create a More Resilient and Just Nation

Large near-term cuts in greenhouse gas emissions are achievable through many currently available and cost-effective mitigation options. However, reaching net-zero emissions by midcentury cannot be achieved without exploring additional mitigation options. Even if the world decarbonizes rapidly, the Nation will continue to face climate impacts and risks. Adequately and equitably addressing these risks involves longer-term inclusive planning, investments in transformative adaptation, and mitigation approaches that consider equity and justice.

Available mitigation strategies can deliver substantial emissions reductions, but additional options are needed to reach net zero

Limiting global temperature change to well below 2°C (3.6°F) requires reaching net-zero CO 2 emissions globally by 2050 and net-zero emissions of all greenhouse gases from human activities within the following few decades (see “Meeting US mitigation targets means reaching net-zero emissions” above). Net-zero emissions pathways involve widespread implementation of currently available and cost-effective options for reducing emissions alongside rapid expansion of technologies and methods to remove carbon from the atmosphere to balance remaining emissions. However, to reach net-zero emissions, additional mitigation options need to be explored (Figure 1.16 ). Pathways to net zero involve large-scale technological, infrastructure, land-use, and behavioral changes and shifts in governance structures. { 5.3 , 6.3 , 9.2 , 9.3 , 10.4 , 13.2 , 16.2 , 18.4 , 20.1 , 24.1 , 25.5 , 30.5 , 32.2 , 32.3 ; Focus on Blue Carbon }

Scenarios that reach net-zero emissions include some of the following key options:

Decarbonizing the electricity sector, primarily through expansion of wind and solar energy, supported by energy storage { 32.2 }

Transitioning to transportation and heating systems that use zero-carbon electricity or low-carbon fuels, such as hydrogen { 5.3 , 13.1 , 32.2 , 32.3 }

Improving energy efficiency in buildings, appliances, and light- and heavy-duty vehicles and other transportation modes { 5.3 , 13.3 , 32.2 }

Implementing urban planning and building design that reduces energy demands through more public transportation and active transportation and lower cooling demands for buildings { 12.3 , 13.1 , 32.2 }

Increasing the efficiency and sustainability of food production, distribution, and consumption { 11.1 , 32.2 }

Improving land management to decrease greenhouse gas emissions and increase carbon removal and storage, with options ranging from afforestation, reforestation, and restoring coastal ecosystems to industrial processes that directly capture and store carbon from the air { 5.3 , 6.3 , 8.3 , 32.2 , 32.3 ; Focus on Blue Carbon }

Due to large declines in technology and deployment costs over the last decade (Figure 1.2 ), decarbonizing the electricity sector is expected to be largely driven by rapid growth in renewable energy. Recent legislation is also expected to increase deployment rates of low- and zero-carbon technology. To reach net-zero targets, the US will need to add new electricity-generating capacity, mostly wind and solar, faster than ever before. This infrastructure expansion may drastically increase demand for products (batteries, solar photovoltaics) and resources, such as metals and critical minerals. Near-term shortages in minerals and metals due to increased demand can be addressed by increased recycling, for example, which can also reduce dependence on imported materials. { 5.2, 5.3 , 17.2 , 25.3 , 32.2 , 32.4 ; Focus on Risks to Supply Chains }

Most US net-zero scenarios require CO 2 removal from the atmosphere to balance residual emissions, particularly from sectors where decarbonization is difficult. In these scenarios, nuclear and hydropower capacity are maintained but not greatly expanded; natural gas–fired generation declines, but more slowly if coupled with carbon capture and storage. { 32.2 }

Nature-based solutions that restore degraded ecosystems and preserve or enhance carbon storage in natural systems like forests, oceans, and wetlands, as well as agricultural lands, are cost-effective mitigation strategies. For example, with conservation and restoration, marine and coastal ecosystems could capture and store enough atmospheric carbon each year to offset about 3% of global emissions (based on 2019 and 2020 emissions). Many nature-based solutions can provide additional benefits, like improved ecosystem resilience, food production, improved water quality, and recreational opportunities. { 8.3 ; Boxes 7.2 , 32.2 ; Focus on Blue Carbon }

Adequately addressing climate risks involves transformative adaptation

While adaptation planning and implementation has advanced in the US, most adaptation actions to date have been incremental and small in scale (see Table 1.3 ). In many cases, more transformative adaptation will be necessary to adequately address the risks of current and future climate change. { 31.1 , 31.3 }.

Transformative adaptation involves fundamental shifts in systems, values, and practices, including assessing potential trade-offs, intentionally integrating equity into adaptation processes, and making systemic changes to institutions and norms. While barriers to adaptation remain, many of these can be overcome with financial, cultural, technological, legislative, or institutional changes. { 31.1 , 31.2 , 31.3 }.

Adaptation planning can more effectively reduce climate risk when it identifies not only disparities in how people are affected by climate change but also the underlying causes of climate vulnerability. Transformative adaptation would involve consideration of both the physical and social drivers of vulnerability and how they interact to shape local experiences of vulnerability and disparities in risk. Examples include understanding how differing levels of access to disaster assistance constrain recovery outcomes or how disaster damage exacerbates long-term wealth inequality. Effective adaptation, both incremental and transformative, involves developing and investing in new monitoring and evaluation methods to understand the different values of, and impacts on, diverse individuals and communities. { 9.3 , 19.3 , 31.2 , 31.3 , 31.5 }

Transformative adaptation would require new and better-coordinated governance mechanisms and cooperation across all levels of government, the private sector, and society. A coordinated, systems-based approach can support consideration of risks that cut across multiple sectors and scales, as well as the development of context-specific adaptations. For example, California, Florida, and other states have used informal regional collaborations to develop adaptation strategies tailored to their area. Adaptation measures that are designed and implemented using inclusive, participatory planning approaches and leverage coordinated governance and financing have the greatest potential for long-term benefits, such as improved quality of life and increased economic productivity. { 10.3 , 18.4 , 20.2 , 31.4 }

Mitigation and adaptation actions can result in systemic, cascading benefits

Actions taken now to accelerate net emissions reductions and adapt to ongoing changes can reduce risks to current and future generations. Mitigation and adaptation actions, from international to individual scales, can also result in a range of benefits beyond limiting harmful climate impacts, including some immediate benefits (Figure 1.1 ). The benefits of mitigation and proactive adaptation investments are expected to outweigh the costs. { 2.3 , 13.3 , 14.5 , 15.3 , 17.4 , 22.1 , 31.6 , 32.4 ; Introductions in Chs. 17 , 31 }

Accelerating the deployment of low-carbon technologies, expanding renewable energy, and improving building efficiency can have significant near-term social and economic benefits like reducing energy costs and creating jobs. { 32.4 }

Transitioning to a carbon-free, sustainable, and resilient transportation system can lead to improvements in air quality, fewer traffic fatalities, lower costs to travelers, improved mental and physical health, and healthier ecosystems. { 13.3 }

Reducing emissions of short-lived climate pollutants like methane, black carbon, and ozone provides immediate air quality benefits that save lives and decrease the burden on healthcare systems while also slowing near-term warming. { 11.1 , 14.5 , 15.3 }

Green infrastructure and nature-based solutions that accelerate pathways to net-zero emissions through restoration and protection of ecological resources can improve water quality, strengthen biodiversity, provide protection from climate hazards like heat extremes or flooding, preserve cultural heritage and traditions, and support more equitable access to environmental amenities. { 8.3 , 15.3 , 20.3 , 24.4 , 30.4 ; Focus on Blue Carbon }

Strategic planning and investment in resilience can reduce the economic impacts of climate change, including costs to households and businesses, risks to markets and supply chains, and potential negative impacts on employment and income, while also providing opportunities for economic gain. { 9.2 , 19.3 , 26.2 , 31.6 ; Focus on Risks to Supply Chains }

Improving cropland management and climate-smart agricultural practices can strengthen the resilience and profitability of farms while also increasing soil carbon uptake and storage, reducing emissions of nitrous oxide and methane, and enhancing agricultural efficiency and yields. { 11.1 , 24.1 , 32.2 }

Climate actions that incorporate inclusive and sustained engagement with overburdened and underserved communities in the design, planning, and implementation of evidence-based strategies can also reduce existing disparities and address social injustices. { 24.3 , 31.2 , 32.4 }

Transformative climate actions can strengthen resilience and advance equity

Fossil fuel–based energy systems have resulted in disproportionate public health burdens on communities of color and/or low-income communities. These same communities are also disproportionately harmed by climate change impacts. { 13.4 , 15.2 , 32.4 }

A “just transition” is the process of responding to climate change with transformative actions that address the root causes of climate vulnerability while ensuring equitable access to jobs; affordable, low-carbon energy; environmental benefits such as reduced air pollution; and quality of life for all. This involves reducing impacts to overburdened communities, increasing resources to underserved communities, and integrating diverse worldviews, cultures, experiences, and capacities into mitigation and adaptation actions. As the country shifts to low-carbon energy industries, a just transition would include job creation and training for displaced fossil fuel workers and addressing existing racial and gender disparities in energy workforces. For example, Colorado agencies are creating plans to guide the state’s transition away from coal, with a focus on economic diversification, job creation, and workforce training for former coal workers. The state’s plan also acknowledges a commitment to communities disproportionately impacted by coal power pollution. { 5.3 , 13.4 , 14.3 , 15.2 , 16.2 , 20.3 , 31.2 , 32.4 ; Figure 20.1 }

A just transition would take into account key aspects of environmental justice:

Recognizing that certain people have borne disparate burdens related to current and historical social injustices and, thus, may have different needs

Ensuring that people interested in and affected by outcomes of decision-making processes are included in those procedures through fair and meaningful engagement

Distributing resources and opportunities over time, including access to data and information, so that no single group or set of individuals receives disproportionate benefits or burdens

{ 20.3 ; Figure 20.1 }

An equitable and sustainable US response to climate change has the potential to reduce climate impacts while improving well-being, strengthening resilience, benefiting the economy, and, in part, redressing legacies of racism and injustice. Transformative adaptation and the transition to a net-zero energy system come with challenges and trade-offs that would need to be considered to avoid exacerbating or creating new social injustices. For example, transforming car-centric transportation systems to emphasize public transit and walkability could increase accessibility for underserved communities and people with limited mobility—if user input and equity are intentionally considered. { 13.4 , 20.3 , 31.3 , 32.4 ; Ch. 31, Introduction }

Equitable responses that assess trade-offs strengthen community resilience and self-determination, often fostering innovative solutions. Engaging communities in identifying challenges and bringing together diverse voices to participate in decision-making allows for more inclusive, effective, and transparent planning processes that account for the structural factors contributing to inequitable climate vulnerability. { 9.3 , 12.4 , 13.4 , 20.2 , 31.4 }

Cover image

Two volunteers help demonstrate and install solar panels in Highland Park, Michigan, in May 2021. The event was hosted by the local nonprofit Soulardarity, which teaches local residents about solar power, installs solar-powered streetlights that also provide wireless internet access, and helps local communities build a just and equitable energy system. Adopting energy storage with decentralized solutions, such as microgrids or off-grid systems, can promote energy equity in overburdened communities. Photo credit: Nick Hagen.

Confidence Level

Loading metrics

Open Access

Integration of urban climate research within the global climate change discourse

Roles Conceptualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliations School of Built Environment, University of New South Wales, Sydney, New South Wales, Australia, ARC Centre of Excellence for Climate Extremes, Sydney, New South Wales, Australia, ARC Centre of Excellence for 21st Century Weather, Sydney, New South Wales, Australia

Affiliation Bochum Urban Climate Lab, Ruhr University Bochum, Bochum, Germany

Roles Writing – original draft, Writing – review & editing

Affiliation School of Geography, University College Dublin, Dublin, Ireland

Affiliations ARC Centre of Excellence for Climate Extremes, Sydney, New South Wales, Australia, ARC Centre of Excellence for 21st Century Weather, Sydney, New South Wales, Australia, Climate Change Research Centre, University of New South Wales, Sydney, New South Wales, Australia

Roles Writing – review & editing

Affiliation School of Arts, Media and Engineering, Arizona State University, Tempe, Arizona, United States of America

Affiliation School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada

Affiliation Climate Adaptation and Disaster Risk Department, Deltares, Delft, The Netherlands

Affiliation Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America

Affiliations ARC Centre of Excellence for Climate Extremes, Sydney, New South Wales, Australia, Climate Change Research Centre, University of New South Wales, Sydney, New South Wales, Australia

Affiliations College of Integrative Studies, Singapore Management University, Singapore, Singapore, Urban Institute, Singapore Management University, Singapore, Singapore

• Negin Nazarian, 
• Benjamin Bechtel, 
• Gerald Mills, 
• Melissa Anne Hart, 
• Ariane Middel, 
• E. Scott Krayenhoff, 
• Gaby S. Langendijk, 
• Lei Zhao, 
• Andy Pitman, 
• Winston Chow

Published: August 26, 2024

• https://doi.org/10.1371/journal.pclm.0000473
• Reader Comments

Citation: Nazarian N, Bechtel B, Mills G, Hart MA, Middel A, Krayenhoff ES, et al. (2024) Integration of urban climate research within the global climate change discourse. PLOS Clim 3(8): e0000473. https://doi.org/10.1371/journal.pclm.0000473

Editor: Jamie Males, PLOS Climate, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND

Copyright: © 2024 Nazarian et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: The author(s) received no specific funding for this work.

Competing interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: Benjamin Bechtel is a member of the PLOS Climate editorial board.

Global climate science needs to address a fundamental challenge: the mismatch between the scales of anthropogenic processes driving change and the resulting climate impacts. While projected climate changes and impacts are global in extent, the drivers of this change, and the exposure to its impacts, are concentrated in densely populated urban areas. Despite occupying only 1–3% of the land, urban areas are home to most of the world’s population and responsible for ~70% of current greenhouse gas emissions [ 1 ]. By 2050, an additional 2.5 billion people are expected to live in urban areas, with up to 90% of this growth anticipated in the Global South with increased rates of vulnerability. The importance of cities in our climate change dialogue will therefore not diminish but rather become increasingly more significant.

Despite the vital role of cities, urban-scale climates are poorly represented in global climate science (both in observations and models). Urban climate research has also been traditionally underrepresented in the assessments of the physical basis of climate, with the inclusion of cities not being formalized until the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which emphasized adaptation and mitigation. This has several consequences. First, a rich body of existing knowledge on urban climates is ignored, particularly in IPCC science assessments. Second, there has been little incentive to measure and understand climate processes at urban scales, which further undermines the accuracy of current climate assessments. Third, urban policies to mitigate and adapt to climate change may not account for unique climate consequences in cities. This limits our ability to develop effective strategies for climate adaptation and mitigation, posing additional risks to the future resilience of societies.

There is a unique opportunity to remedy this situation with the planned Special Report on Climate Change and Cities as part of the IPCC’s 7th Assessment Cycle. This marks the first time the IPCC has dedicated a coordinated effort focused on cities. This initiative is timely, addressing stakeholder demand for policy-relevant information in urban areas and considering two developments in urban climate science research. First, there is evidence that cities not only create distinctive climates but also impact regional climates and extreme events beyond their physical boundaries. The contribution of urbanization to urban temperature, for example, can equal or exceed the global climate change signal in many cities [ 2 ]. Urbanization similarly exacerbates heatwaves, alters the water cycle, and generates increased precipitation over and downwind of some cities. These regional effects, on par with those of non-urban land cover change, underscore the role of cities in exacerbating climate hazards in compounding ways that are not yet systematically quantified [ 3 ].

Second, advances in climate modeling at various scales have achieved higher resolutions, making omitting urban areas increasingly problematic. While models at a ~50 km resolution or coarser might justify focusing on broader-scale processes, finer resolution simulations suffer from significant biases if urban areas are neglected. This is especially the case for kilometer-scale simulations that many major modeling centers are now attempting.

Over the last 35 years, an active interdisciplinary Urban Climate Research community has acquired substantial knowledge and understanding of urban modifications to micro- to meso-scale climates. At their most recent tri-annual gathering, the 11 th International Conference on Urban Climate (ICUC11) held at the University of New South Wales in 2023, 640 experts gathered to discuss the latest developments in urban climate science. This community plays a pivotal role in integrating the physical understanding of urban climate processes in global climate change discussions.

One of the most prominent discussions at ICUC11 centered around strategies to enhance our community’s active involvement in shaping present and future global initiatives, including, but not limited to, IPCC reports. Our commentary reflects on these discussions, declaring and underscoring the collective commitment of the urban climate community to achieving a broader impact in climate change discourse ( Fig 1 ).

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

https://doi.org/10.1371/journal.pclm.0000473.g001

It is paramount that the Urban Climate community engages in strategic and coordinated planning to meet this historic opportunity provided by the IPCC Special Report on Climate Change and Cities and the 7th Assessment Report (AR7). To do so, three pivotal aspects should be addressed and strengthened:

• Prioritize urban-scale technological advancements: There is a pressing need to improve the capabilities of high-resolution global and regional climate models and better understand global climate interactions with city-scale processes. Capturing these interactions requires a range of observations across scales, from novel remote sensing platforms to fine-scale IoT sensor platforms, in addition to improved modelling capabilities. It is particularly important to better capture urban dynamics across spatial and temporal scales in larger (regional to global) climate models and further develop a hierarchy of approaches (at different spatial and temporal scales) to quantify the two-way interactions between cities and climate change.
• Facilitate cross-disciplinary and cross-scale synergies: The evolving focus on the impact of climate change on urban communities necessitates integrating urban climate research into broader-scale climate assessments. The impact of climate change on cities, as well as the impact of cities on climate change, can no longer be assessed in isolation. There is a strong need for synergistic approaches that go beyond disciplinary focuses and put urban climate research into the context of not only climate impact assessments but also applications (such as climate services) and policies that can be taken up by city governance.
• Increase urban climate visibility and presence: Streamlining the process for integrating urban climate research into IPCC assessments requires a stronger presence of urban climate experts across all three IPCC working groups in various capacities, including as scoping experts, authors, and expert reviewers. Furthermore, integration of our work requires not only better communication of aggregated knowledge in urban climate research (synthesized from various case studies in different cities and climatic contexts) but also better integration in the global sustainability context.

To inform various steps of this process, the urban climate community has a responsibility to identify and address the most critical research gaps that are relevant to the nexus of cities and climate change . This covers research areas including, but not limited to: urban climate modeling across scales (including urban representation in the next generation of high-resolution global and regional climate models as well as climate projections at the city scale), urban climate observations (including remote sensing, in situ, and urban climate informatics), urban climate hazards and their compounding impacts (such as heat, air quality, flood), urban greenhouse gas emissions, urban climate justice, as well as integrated urban climate services developed across global case studies.

Equally important is synthesizing and aggregating existing urban climate knowledge in various subfields in ways that are robust, comprehensive, and accessible to IPCC authors with expertise in various climate disciplines. This synthesis could focus on developing urban typologies that codify settlements based on urban form, structure, metabolism, and networks, and their implications on climate adaptation and mitigation. For these syntheses to be effective, they should be achieved with urban stakeholders from diverse topical, career stages, and geographic representations that contribute to aggregating and synthesizing state-of-the-art knowledge.

Our community pledges to champion robust knowledge synthesis, inclusive representation, and active engagement, aiming to shape the global discourse on climate change and urban environments for a sustainable future.

• View Article
• Google Scholar

FOURTH NATIONAL CLIMATE ASSESSMENT Volume II: Impacts, Risks, and Adaptation in the United States

The National Climate Assessment (NCA) assesses the science of climate change and variability and its impacts across the United States, now and throughout this century.

SUMMARY FINDINGS

Report chapters.

Volume I presents an assessment of the physical science underlying this report: science2017.globalchange.gov

FOURTH NATIONAL CLIMATE ASSESSMENT

Summary findings.

These Summary Findings represent a high-level synthesis of the material in the underlying report. The findings consolidate Key Messages and supporting evidence from 16 national-level topic chapters, 10 regional chapters, and 2 chapters that focus on societal response strategies (mitigation and adaptation). Unless otherwise noted, qualitative statements regarding future conditions in these Summary Findings are broadly applicable across the range of different levels of future climate change and associated impacts considered in this report.

1. Communities

Climate change creates new risks and exacerbates existing vulnerabilities in communities across the United States, presenting growing challenges to human health and safety, quality of life, and the rate of economic growth.

The impacts of climate change are already being felt in communities across the country. More frequent and intense extreme weather and climate-related events, as well as changes in average climate conditions, are expected to continue to damage infrastructure, ecosystems, and social systems that provide essential benefits to communities. Future climate change is expected to further disrupt many areas of life, exacerbating existing challenges to prosperity posed by aging and deteriorating infrastructure, stressed ecosystems, and economic inequality. Impacts within and across regions will not be distributed equally. People who are already vulnerable, including lower-income and other marginalized communities, have lower capacity to prepare for and cope with extreme weather and climate-related events and are expected to experience greater impacts. Prioritizing adaptation actions for the most vulnerable populations would contribute to a more equitable future within and across communities. Global action to significantly cut greenhouse gas emissions can substantially reduce climate-related risks and increase opportunities for these populations in the longer term.

Without substantial and sustained global mitigation and regional adaptation efforts, climate change is expected to cause growing losses to American infrastructure and property and impede the rate of economic growth over this century.

In the absence of significant global mitigation action and regional adaptation efforts, rising temperatures, sea level rise, and changes in extreme events are expected to increasingly disrupt and damage critical infrastructure and property, labor productivity, and the vitality of our communities. Regional economies and industries that depend on natural resources and favorable climate conditions, such as agriculture, tourism, and fisheries, are vulnerable to the growing impacts of climate change. Rising temperatures are projected to reduce the efficiency of power generation while increasing energy demands, resulting in higher electricity costs. The impacts of climate change beyond our borders are expected to increasingly affect our trade and economy, including import and export prices and U.S. businesses with overseas operations and supply chains. Some aspects of our economy may see slight near-term improvements in a modestly warmer world. However, the continued warming that is projected to occur without substantial and sustained reductions in global greenhouse gas emissions is expected to cause substantial net damage to the U.S. economy throughout this century, especially in the absence of increased adaptation efforts. With continued growth in emissions at historic rates, annual losses in some economic sectors are projected to reach hundreds of billions of dollars by the end of the century—more than the current gross domestic product (GDP) of many U.S. states.

3. Interconnected Impacts

Climate change affects the natural, built, and social systems we rely on individually and through their connections to one another. These interconnected systems are increasingly vulnerable to cascading impacts that are often difficult to predict, threatening essential services within and beyond the Nation’s borders.

Climate change presents added risks to interconnected systems that are already exposed to a range of stressors such as aging and deteriorating infrastructure, land-use changes, and population growth. Extreme weather and climate-related impacts on one system can result in increased risks or failures in other critical systems, including water resources, food production and distribution, energy and transportation, public health, international trade, and national security. The full extent of climate change risks to interconnected systems, many of which span regional and national boundaries, is often greater than the sum of risks to individual sectors. Failure to anticipate interconnected impacts can lead to missed opportunities for effectively managing the risks of climate change and can also lead to management responses that increase risks to other sectors and regions. Joint planning with stakeholders across sectors, regions, and jurisdictions can help identify critical risks arising from interaction among systems ahead of time.

4. Actions to Reduce Risks

Communities, governments, and businesses are working to reduce risks from and costs associated with climate change by taking action to lower greenhouse gas emissions and implement adaptation strategies. While mitigation and adaptation efforts have expanded substantially in the last four years, they do not yet approach the scale considered necessary to avoid substantial damages to the economy, environment, and human health over the coming decades.

Future risks from climate change depend primarily on decisions made today. The integration of climate risk into decision-making and the implementation of adaptation activities have significantly increased since the Third National Climate Assessment in 2014, including in areas of financial risk reporting, capital investment planning, development of engineering standards, military planning, and disaster risk management. Transformations in the energy sector—including the displacement of coal by natural gas and increased deployment of renewable energy—along with policy actions at the national, regional, state, and local levels are reducing greenhouse gas emissions in the United States. While these adaptation and mitigation measures can help reduce damages in a number of sectors, this assessment shows that more immediate and substantial global greenhouse gas emissions reductions, as well as regional adaptation efforts, would be needed to avoid the most severe consequences in the long term. Mitigation and adaptation actions also present opportunities for additional benefits that are often more immediate and localized, such as improving local air quality and economies through investments in infrastructure. Some benefits, such as restoring ecosystems and increasing community vitality, may be harder to quantify.

The quality and quantity of water available for use by people and ecosystems across the country are being affected by climate change, increasing risks and costs to agriculture, energy production, industry, recreation, and the environment.

Rising air and water temperatures and changes in precipitation are intensifying droughts, increasing heavy downpours, reducing snowpack, and causing declines in surface water quality, with varying impacts across regions. Future warming will add to the stress on water supplies and adversely impact the availability of water in parts of the United States. Changes in the relative amounts and timing of snow and rainfall are leading to mismatches between water availability and needs in some regions, posing threats to, for example, the future reliability of hydropower production in the Southwest and the Northwest. Groundwater depletion is exacerbating drought risk in many parts of the United States, particularly in the Southwest and Southern Great Plains. Dependable and safe water supplies for U.S. Caribbean, Hawai‘i, and U.S.-Affiliated Pacific Island communities are threatened by drought, flooding, and saltwater contamination due to sea level rise. Most U.S. power plants rely on a steady supply of water for cooling, and operations are expected to be affected by changes in water availability and temperature increases. Aging and deteriorating water infrastructure, typically designed for past environmental conditions, compounds the climate risk faced by society. Water management strategies that account for changing climate conditions can help reduce present and future risks to water security, but implementation of such practices remains limited.

Impacts from climate change on extreme weather and climate-related events, air quality, and the transmission of disease through insects and pests, food, and water increasingly threaten the health and well-being of the American people, particularly populations that are already vulnerable.

Changes in temperature and precipitation are increasing air quality and health risks from wildfire and ground-level ozone pollution. Rising air and water temperatures and more intense extreme events are expected to increase exposure to waterborne and foodborne diseases, affecting food and water safety. With continued warming, cold-related deaths are projected to decrease and heat-related deaths are projected to increase; in most regions, increases in heat-related deaths are expected to outpace reductions in cold-related deaths. The frequency and severity of allergic illnesses, including asthma and hay fever, are expected to increase as a result of a changing climate. Climate change is also projected to alter the geographic range and distribution of disease-carrying insects and pests, exposing more people to ticks that carry Lyme disease and mosquitoes that transmit viruses such as Zika, West Nile, and dengue, with varying impacts across regions. Communities in the Southeast, for example, are particularly vulnerable to the combined health impacts from vector-borne disease, heat, and flooding. Extreme weather and climate-related events can have lasting mental health consequences in affected communities, particularly if they result in degradation of livelihoods or community relocation. Populations including older adults, children, low-income communities, and some communities of color are often disproportionately affected by, and less resilient to, the health impacts of climate change. Adaptation and mitigation policies and programs that help individuals, communities, and states prepare for the risks of a changing climate reduce the number of injuries, illnesses, and deaths from climate-related health outcomes.

7. Indigenous Peoples

Climate change increasingly threatens Indigenous communities’ livelihoods, economies, health, and cultural identities by disrupting interconnected social, physical, and ecological systems.

Many Indigenous peoples are reliant on natural resources for their economic, cultural, and physical well-being and are often uniquely affected by climate change. The impacts of climate change on water, land, coastal areas, and other natural resources, as well as infrastructure and related services, are expected to increasingly disrupt Indigenous peoples’ livelihoods and economies, including agriculture and agroforestry, fishing, recreation, and tourism. Adverse impacts on subsistence activities have already been observed. As climate changes continue, adverse impacts on culturally significant species and resources are expected to result in negative physical and mental health effects. Throughout the United States, climate-related impacts are causing some Indigenous peoples to consider or actively pursue community relocation as an adaptation strategy, presenting challenges associated with maintaining cultural and community continuity. While economic, political, and infrastructure limitations may affect these communities’ ability to adapt, tightly knit social and cultural networks present opportunities to build community capacity and increase resilience. Many Indigenous peoples are taking steps to adapt to climate change impacts structured around self-determination and traditional knowledge, and some tribes are pursuing mitigation actions through development of renewable energy on tribal lands.

8. Ecosystems and Ecosystem Services

Ecosystems and the benefits they provide to society are being altered by climate change, and these impacts are projected to continue. Without substantial and sustained reductions in global greenhouse gas emissions, transformative impacts on some ecosystems will occur; some coral reef and sea ice ecosystems are already experiencing such transformational changes.

Many benefits provided by ecosystems and the environment, such as clean air and water, protection from coastal flooding, wood and fiber, crop pollination, hunting and fishing, tourism, cultural identities, and more will continue to be degraded by the impacts of climate change. Increasing wildfire frequency, changes in insect and disease outbreaks, and other stressors are expected to decrease the ability of U.S. forests to support economic activity, recreation, and subsistence activities. Climate change has already had observable impacts on biodiversity, ecosystems, and the benefits they provide to society. These impacts include the migration of native species to new areas and the spread of invasive species. Such changes are projected to continue, and without substantial and sustained reductions in global greenhouse gas emissions, extinctions and transformative impacts on some ecosystems cannot be avoided in the long term. Valued aspects of regional heritage and quality of life tied to ecosystems, wildlife, and outdoor recreation will change with the climate, and as a result, future generations can expect to experience and interact with the natural environment in ways that are different from today. Adaptation strategies, including prescribed burning to reduce fuel for wildfire, creation of safe havens for important species, and control of invasive species, are being implemented to address emerging impacts of climate change. While some targeted response actions are underway, many impacts, including losses of unique coral reef and sea ice ecosystems, can only be avoided by significantly reducing global emissions of carbon dioxide and other greenhouse gases.

9. Agriculture

Rising temperatures, extreme heat, drought, wildfire on rangelands, and heavy downpours are expected to increasingly disrupt agricultural productivity in the United States. Expected increases in challenges to livestock health, declines in crop yields and quality, and changes in extreme events in the United States and abroad threaten rural livelihoods, sustainable food security, and price stability.

Climate change presents numerous challenges to sustaining and enhancing crop productivity, livestock health, and the economic vitality of rural communities. While some regions (such as the Northern Great Plains) may see conditions conducive to expanded or alternative crop productivity over the next few decades, overall, yields from major U.S. crops are expected to decline as a consequence of increases in temperatures and possibly changes in water availability, soil erosion, and disease and pest outbreaks. Increases in temperatures during the growing season in the Midwest are projected to be the largest contributing factor to declines in the productivity of U.S. agriculture. Projected increases in extreme heat conditions are expected to lead to further heat stress for livestock, which can result in large economic losses for producers. Climate change is also expected to lead to large-scale shifts in the availability and prices of many agricultural products across the world, with corresponding impacts on U.S. agricultural producers and the U.S. economy. These changes threaten future gains in commodity crop production and put rural livelihoods at risk. Numerous adaptation strategies are available to cope with adverse impacts of climate variability and change on agricultural production. These include altering what is produced, modifying the inputs used for production, adopting new technologies, and adjusting management strategies. However, these strategies have limits under severe climate change impacts and would require sufficient long- and short-term investment in changing practices.

10. Infrastructure

Our Nation’s aging and deteriorating infrastructure is further stressed by increases in heavy precipitation events, coastal flooding, heat, wildfires, and other extreme events, as well as changes to average precipitation and temperature. Without adaptation, climate change will continue to degrade infrastructure performance over the rest of the century, with the potential for cascading impacts that threaten our economy, national security, essential services, and health and well-being.

Climate change and extreme weather events are expected to increasingly disrupt our Nation’s energy and transportation systems, threatening more frequent and longer-lasting power outages, fuel shortages, and service disruptions, with cascading impacts on other critical sectors. Infrastructure currently designed for historical climate conditions is more vulnerable to future weather extremes and climate change. The continued increase in the frequency and extent of high-tide flooding due to sea level rise threatens America’s trillion-dollar coastal property market and public infrastructure, with cascading impacts to the larger economy. In Alaska, rising temperatures and erosion are causing damage to buildings and coastal infrastructure that will be costly to repair or replace, particularly in rural areas; these impacts are expected to grow without adaptation. Expected increases in the severity and frequency of heavy precipitation events will affect inland infrastructure in every region, including access to roads, the viability of bridges, and the safety of pipelines. Flooding from heavy rainfall, storm surge, and rising high tides is expected to compound existing issues with aging infrastructure in the Northeast. Increased drought risk will threaten oil and gas drilling and refining, as well as electricity generation from power plants that rely on surface water for cooling. Forward-looking infrastructure design, planning, and operational measures and standards can reduce exposure and vulnerability to the impacts of climate change and reduce energy use while providing additional near-term benefits, including reductions in greenhouse gas emissions.

11. Oceans & Coasts

Coastal communities and the ecosystems that support them are increasingly threatened by the impacts of climate change. Without significant reductions in global greenhouse gas emissions and regional adaptation measures, many coastal regions will be transformed by the latter part of this century, with impacts affecting other regions and sectors. Even in a future with lower greenhouse gas emissions, many communities are expected to suffer financial impacts as chronic high-tide flooding leads to higher costs and lower property values.

Rising water temperatures, ocean acidification, retreating arctic sea ice, sea level rise, high-tide flooding, coastal erosion, higher storm surge, and heavier precipitation events threaten our oceans and coasts. These effects are projected to continue, putting ocean and marine species at risk, decreasing the productivity of certain fisheries, and threatening communities that rely on marine ecosystems for livelihoods and recreation, with particular impacts on fishing communities in Hawai‘i and the U.S.-Affiliated Pacific Islands, the U.S. Caribbean, and the Gulf of Mexico. Lasting damage to coastal property and infrastructure driven by sea level rise and storm surge is expected to lead to financial losses for individuals, businesses, and communities, with the Atlantic and Gulf Coasts facing above-average risks. Impacts on coastal energy and transportation infrastructure driven by sea level rise and storm surge have the potential for cascading costs and disruptions across the country. Even if significant emissions reductions occur, many of the effects from sea level rise over this century—and particularly through mid-century—are already locked in due to historical emissions, and many communities are already dealing with the consequences. Actions to plan for and adapt to more frequent, widespread, and severe coastal flooding, such as shoreline protection and conservation of coastal ecosystems, would decrease direct losses and cascading impacts on other sectors and parts of the country. More than half of the damages to coastal property are estimated to be avoidable through well-timed adaptation measures. Substantial and sustained reductions in global greenhouse gas emissions would also significantly reduce projected risks to fisheries and communities that rely on them.

12. Tourism and Recreation

Outdoor recreation, tourist economies, and quality of life are reliant on benefits provided by our natural environment that will be degraded by the impacts of climate change in many ways.

Climate change poses risks to seasonal and outdoor economies in communities across the United States, including impacts on economies centered around coral reef-based recreation, winter recreation, and inland water-based recreation. In turn, this affects the well-being of the people who make their living supporting these economies, including rural, coastal, and Indigenous communities. Projected increases in wildfire smoke events are expected to impair outdoor recreational activities and visibility in wilderness areas. Declines in snow and ice cover caused by warmer winter temperatures are expected to negatively impact the winter recreation industry in the Northwest, Northern Great Plains, and the Northeast. Some fish, birds, and mammals are expected to shift where they live as a result of climate change, with implications for hunting, fishing, and other wildlife-related activities. These and other climate-related impacts are expected to result in decreased tourism revenue in some places and, for some communities, loss of identity. While some new opportunities may emerge from these ecosystem changes, cultural identities and economic and recreational opportunities based around historical use of and interaction with species or natural resources in many areas are at risk. Proactive management strategies, such as the use of projected stream temperatures to set priorities for fish conservation, can help reduce disruptions to tourist economies and recreation.

External Link

Preprint  

• Preprint hess-2024-260

Adaptation of root zone storage capacity to climate change and its effects on future streamflow in Alpine catchments: towards non-stationary model parameters

Abstract. Hydrological models play a vital role in projecting future changes in streamflow. Despite the strong awareness of non-stationarity in hydrological system characteristics, model parameters are typically assumed to be stationary and derived through calibration on past conditions. Integrating the dynamics of system change in hydrological models remains challenging due to uncertainties related to future changes in climate and ecosystems.

Nevertheless, there is increasing evidence that vegetation adjusts its root zone storage capacity – considered a critical parameter in hydrological models – to prevailing hydroclimatic conditions. This adaptation of the root zone to moisture deficits can be estimated by the Memory Method. When combined with long-term water budget estimates in the Budyko framework, the Memory method offers a promising approach to estimate future climate-vegetation interaction and thus time-variable parameters in process-based hydrological models.

Our study provides an exploratory analysis of non-stationary parameters for root zone storage capacity in hydrological models for projecting streamflow in six catchments in the Austrian Alps, specifically investigating how future changes in root zone storage impact modeled streamflow. Using the Memory method, we derive climate-based parameter estimates of the root zone storage capacity under historical and projected future climate conditions. These climate-based estimates are then implemented in our hydrological model to assess the resultant impact on modeled past and future streamflow.

Our findings indicate that climate-based parameter estimations significantly narrow the parameter ranges linked to root zone storage capacity. This contrasts with the broader ranges obtained solely through calibration. Moreover, using projections from 14 climate models, our findings indicate a substantial increase in the root zone storage capacity parameters across all catchments in the future, ranging from +10 % to +100 %. Despite these alterations, the model performance remains relatively consistent when evaluating past streamflow, independent of using calibrated or climate-based estimations for the root zone storage capacity parameter. Additionally, no significant differences are found when modeling future streamflow when including future climate-induced adaptation of the root zone storage capacity in the hydrological model. Variations in annual mean, maximum, and minimum flows remain within a 5 % range, with slight increases found for monthly streamflow and runoff coefficients. Our research shows that although climate-induced changes in root zone storage capacity occur, they do not notably affect future streamflow projections in the Alpine catchments under study. Our findings suggest that incorporating a dynamic representation of the root zone storage capacity parameter may not be crucial for modeling streamflow in humid and energy-limited catchments. However, our observations indicate relatively larger changes in root zone storage capacity within the less humid catchments, corresponding to higher variations in modeled future streamflow. This suggests a potentially higher importance of dynamic representations of root zone characteristics in arid regions and underscores the necessity for further research on non-stationarity in these regions.

• Preprint (PDF, 7850 KB)
• Supplement (16168 KB)
• Preprint (7850 KB)
• Metadata XML

Status : open (until 22 Oct 2024)

Report abuse

Please provide a reason why you see this comment as being abusive. You might include your name and email but you can also stay anonymous.

Please provide a reason why you see this comment as being abusive.

Please confirm reCaptcha.

https://doi.org/10.5194/hess-2024-260-supplement

• Supplement: 20

Viewed (geographical distribution)

Magali Ponds

Sarah hanus, harry zekollari, marie-claire ten veldhuis, gerrit schoups, roland kaitna, markus hrachowitz.

Information

• Author Services

Initiatives

You are accessing a machine-readable page. In order to be human-readable, please install an RSS reader.

All articles published by MDPI are made immediately available worldwide under an open access license. No special permission is required to reuse all or part of the article published by MDPI, including figures and tables. For articles published under an open access Creative Common CC BY license, any part of the article may be reused without permission provided that the original article is clearly cited. For more information, please refer to https://www.mdpi.com/openaccess .

Feature papers represent the most advanced research with significant potential for high impact in the field. A Feature Paper should be a substantial original Article that involves several techniques or approaches, provides an outlook for future research directions and describes possible research applications.

Feature papers are submitted upon individual invitation or recommendation by the scientific editors and must receive positive feedback from the reviewers.

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

Original Submission Date Received: .

• Active Journals
• Find a Journal
• Proceedings Series
• For Authors
• For Reviewers
• For Editors
• For Librarians
• For Publishers
• For Societies
• For Conference Organizers
• Open Access Policy
• Institutional Open Access Program
• Special Issues Guidelines
• Editorial Process
• Research and Publication Ethics
• Article Processing Charges
• Testimonials
• Preprints.org
• SciProfiles
• Encyclopedia

Article Menu

• Subscribe SciFeed
• Recommended Articles
• Google Scholar
• on Google Scholar
• Table of Contents

Find support for a specific problem in the support section of our website.

Please let us know what you think of our products and services.

Visit our dedicated information section to learn more about MDPI.

JSmol Viewer

A comparative study on 2015 and 2023 chennai flooding: a multifactorial perspective.

1. Introduction

2. study area, 3. materials and methods, 3.1. materials, 3.2. methodology, 4.1. rainfall analysis, 4.2. spatial mapping of flood, 4.3. integrated reservoir study for flood events, 4.4. study of cyclone activities and tidal wave heights during the flood event, 4.5. effects of enso/iod on northeast monsoon, 5. discussion, 6. conclusions, supplementary materials, author contributions, data availability statement, conflicts of interest.

• Huang, M.; Jin, S. Rapid flood mapping and evaluation with a supervised classifier and change detection in Shouguang using Sentinel-1 SAR and Sentinel-2 optical data. Remote Sens. 2020 , 12 , 2073. [ Google Scholar ] [ CrossRef ]
• Mahmood, S.; Sajjad, A.; Rahman, A.-U. Cause and damage analysis of 2010 flood disaster in district Muzaffar Garh, Pakistan. Nat. Hazards 2021 , 107 , 1681–1692. [ Google Scholar ] [ CrossRef ]
• Hunt, J. Inland and coastal flooding: Developments in prediction and prevention. Philos. Trans. R. Soc. 2005 , 363 , 1475–1491. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Choi, C.; Han, D.; Kim, J.-W.; Jung, J.; Kim, D.; Kim, H.S. Mega Flood Simulation Assuming Successive Extreme Rainfall Events. Korean Wetl. Soc. 2016 , 18 , 76–83. [ Google Scholar ]
• UNDRR. Human Cost of Disasters: An Overview of the Last 20 Years 2000–2019. Available online: https://www.undrr.org/publication/human-cost-disasters-overview-last-20-years-2000-2019 (accessed on 2 June 2024).
• Ferk, M.; Ciglič, R.; Komac, B.; Loczy, D. Management of small retention ponds and their impact on flood hazard prevention in the Slovenske gorice hill. Acta Geogr. Slov. 2020 , 60 , 107–125. [ Google Scholar ] [ CrossRef ]
• Rahman, M.; Ningsheng, C.; Islam, M.; Dewan, A.; Iqbal, J.; Washakh, R.M.A.; Shufeng, T. Flood Susceptibility Assessment in Bangladesh Using Machine Learning and Multi-criteria Decision Analysis. Earth Syst. Environ. 2019 , 3 , 585–601. [ Google Scholar ] [ CrossRef ]
• Sivanpillai, R.; Jacobs, K.M.; Mattilio, C.M.; Piskorski, E.V. Rapid flood inundation mapping by differencing water indices from pre- and post-flood Landsat images. Front. Earth Sci. 2021 , 15 , 1–11. [ Google Scholar ] [ CrossRef ]
• Wang, Y.; Colby, J.D.; Mulcahy, K.A. Mulcahy. An efficient method for mapping flood extent in a coastal floodplain using Landsat TM and DEM data. Int. J. Remote Sens. 2002 , 23 , 3681–3696. [ Google Scholar ] [ CrossRef ]
• Schumann, G.; Giustarini, L.; Tarpanelli, A.; Jarihani, B.; Martinis, S. Martinis. Flood Modeling and Prediction Using Earth Observation Data. Surv. Geophys. 2022 , 44 , 1553–1578. [ Google Scholar ] [ CrossRef ]
• Hidayah, E.; Pranadiarso, T.; Halik, G.; Indarto, I.; Lee, W.K.; Maruf, M.F. Flood Mapping Based on Open-Source Remote Sensing Data Using an Efficient Band Combination System. Acta Geogr. Slov. 2022 , 62 , 48. [ Google Scholar ] [ CrossRef ]
• Toma, A.; Sandric, I. Mapping flooded areas using Sentinel-1 radar satellite imagery series through Machine learning and Deep learning methods. In Proceedings of the EGU General Assembly Conference Abstracts, Vienna, Austria, 23–27 May 2022; p. 2947. [ Google Scholar ]
• Mamatha, N.; Bagali, M.U.; Thangadurai, N. Thangadurai. Disasters Detection from Remote Satellite Images using ML and Deep Learning Approaches. In Proceedings of the International Interdisciplinary Humanitarian Conference for Sustainability IIHC 2022, Bengaluru, India, 18–19 November 2022; pp. 1608–1615. [ Google Scholar ]
• Tiwari, V.; Kumar, V.; Matin, M.A.; Thapa, A.; Ellenburg, W.L.; Gupta, N.; Thapa, S. Flood inundation mapping-Kerala 2018; Harnessing the power of SAR, automatic threshold detection method and Google Earth Engine. PLoS ONE 2020 , 15 , e0237324. [ Google Scholar ] [ CrossRef ]
• Albano, R.; Mancusi, L.; Adamowski, J.; Cantisani, A.; Sole, A. A GIS tool for mapping dam-break flood hazards in Italy. ISPRS Int. J. Geo-Inf. 2019 , 8 , 250. [ Google Scholar ] [ CrossRef ]
• Koskinas, A.; Tegos, A.; Tsira, P.; Dimitriadis, P.; Iliopoulou, T.; Papanicolaou, P.; Koutsoyiannis, D.; Williamson, T. Insights into the Oroville dam 2017 Spillway incident. Geosciences 2019 , 9 , 37. [ Google Scholar ] [ CrossRef ]
• Rotta, L.H.S.; Alcântara, E.; Park, E.; Negri, R.G.; Lin, Y.N.; Bernardo, N.; Mendes, T.S.G.; Filho, C.R.S. The 2019 Brumadinho tailings dam collapse: Possible cause and impacts of the worst human and environmental disaster in Brazil. Int. J. Appl. Earth Obs. Geoinf. 2020 , 90 , 102119. [ Google Scholar ]
• Latrubesse, E.M.; Park, E.; Sieh, K.; Dang, T.; Lin, Y.N.; Yun, S.-H. Dam failure and a catastrophic flood in the Mekong basin (Bolaven Plateau), southern Laos, 2018. Geomorphology 2020 , 362 , 107221. [ Google Scholar ] [ CrossRef ]
• Dave, P. Hidroituango: Another Landslide Crisis at a Hydroelectric Dam ; AGU: Washington, DC, USA, 2019. [ Google Scholar ]
• Ashok, K.; Guan, Z.; Yamagata, T. Impact of the Indian Ocean dipole on the relationship between the Indian monsoon rainfall and ENSO. Geophys. Res. Lett. 2001 , 28 , 4499–4502. [ Google Scholar ] [ CrossRef ]
• Ajayamohan, R.; Rao, S.A. Indian ocean dipole modulates the number of extreme rainfall events over India in a warming environment. J. Meteorol. Soc. Jpn. Ser. II 2008 , 86 , 245–252. [ Google Scholar ] [ CrossRef ]
• Pervez, M.S.; Henebry, G.M. Spatial and seasonal responses of precipitation in the Ganges and Brahmaputra river basins to ENSO and Indian Ocean dipole modes: Implications for flooding and drought. Nat. Hazards Earth Syst. Sci. 2015 , 15 , 147–162. [ Google Scholar ] [ CrossRef ]
• Mohan, M.G.; Fathima, S.; Adarsh, S.; Baiju, N.; Nair, G.A.; Meenakshi, S.; Krishnan, M.S. Analyzing the streamflow teleconnections of greater Pampa basin, Kerala, India using wavelet coherence. Phys. Chem. Earth 2023 , 131 , 103446. [ Google Scholar ] [ CrossRef ]
• Hrudya, P.H.; Varikoden, H.; Vishnu, R. Vishnu. A review on the Indian summer monsoon rainfall, variability and its association with ENSO and IOD. Meteorol. Atmospheric Phys. 2020 , 133 , 1–14. [ Google Scholar ] [ CrossRef ]
• Akilan, A.; Balaji, S.; Azeez, K.K.A.; Satyanarayanan, M. Source and causes of 2015 great pluvial flood of Chennai, Tamil Nadu and its surroundings. J. Geol. Soc. India 2017 , 90 , 602–608. [ Google Scholar ] [ CrossRef ]
• Dehghani, M.; Saghafian, B.; Rivaz, F.; Khodadadi, A. Khodadadi. Evaluation of dynamic regression and artificial neural networks models for real-time hydrological drought forecasting. Arab. J. Geosci. 2017 , 10 , 266. [ Google Scholar ] [ CrossRef ]
• Choubin, B.; Zehtabian, G.; Azareh, A.; Rafiei-Sardooi, E.; Sajedi-Hosseini, F.; Kişi, Ö. Precipitation forecasting using classification and regression trees (CART) model: A comparative study of different approaches. Environ. Earth Sci. 2018 , 77 , 314. [ Google Scholar ] [ CrossRef ]
• Leo Breiman, C.J.S.; Friedman, J.; Olshen, R.A. Classification and Regression Trees , 1st ed.; Chapman and Hall/CRC: New York, NY, USA, 1984. [ Google Scholar ]
• Etemad-Shahidi, A.; Mahjoobi, J. Comparison between M5′ model tree and neural networks for prediction of significant wave height in Lake Superior. Ocean Eng. 2009 , 36 , 1175–1181. [ Google Scholar ] [ CrossRef ]
• Mosavi, A.; Ozturk, P.; Chau, K.-W. Flood prediction using machine learning models: Literature review. Water 2018 , 10 , 1536. [ Google Scholar ] [ CrossRef ]
• Smetanin, S.; Komarov, M. Misclassification Bias in Computational Social Science: A Simulation Approach for Assessing the Impact of Classification Errors on Social Indicators Research. IEEE Access 2022 , 10 , 18886–18898. [ Google Scholar ] [ CrossRef ]
• National Bulletin No. 19, India Meteorological Department. 2023. Available online: https://reliefweb.int/report/myanmar/india-meteorological-department-bulletin-no-19-bob022023-time-issue-1700-hours-ist-dated-12052023 (accessed on 14 December 2023).
• IMD. Forecasting Circular No. 5/2015. 2015. Available online: https://imdsikkim.gov.in/FCT.pdf (accessed on 8 December 2023).
• Gupta, A.K.; Nair, S.S. Urban floods in Bangalore and Chennai: Risk management challenges and lessons for sustainable urban ecology. Curr. Sci. 2011 , 100 , 1638–1645. [ Google Scholar ]
• Lavanya, A.K. Urban flood management—A case study of Chennai city. Arch. Res. 2012 , 2 , 115–121. [ Google Scholar ] [ CrossRef ]
• Rekha, Y.; Suriya, S.; Arul, C. Flood Management Policies in Megacities: A Case Study of Southern India. In Smart Cities ; CRC Press: Boca Raton, FL, USA, 2022; pp. 197–208. [ Google Scholar ]
• Selvaraj, K.; Pandiyan, J.; Yoganandan, V.; Agoramoorthy, G. India contemplates climate change concerns after floods ravaged the coastal city of Chennai. Ocean Coast. Manag. 2016 , 129 , 10–14. [ Google Scholar ] [ CrossRef ]
• Ramasamy, S.M.; Vijay, A.; Dhinesh, S. Geo-anthropogenic aberrations and Chennai floods: 2015, India. Nat. Hazards 2018 , 92 , 443–477. [ Google Scholar ] [ CrossRef ]
• IMD. Heavy Rainfall over Southeast India during November & Early December 2015. Available online: https://nwp.imd.gov.in/NWP-CHENNAI-RAINFALL-REPORT-2015.pdf (accessed on 8 December 2023).
• Balaji Narasimhan, P.M.; Bhallamudi, S.M.; Mondal, A. Chennai Floods 2015: A Rapid Assessment ; Report; Interdisciplinary Centre for Water Research: Bengaluru, India, 2016. [ Google Scholar ]
• Konduru, R.T.; Mrudula, G.; Singh, V.; Srivastava, A.K.; Singh, A.K. Unravelling the causes of 2015 winter monsoon extreme rainfall and floods over Chennai: Influence of atmospheric variability and urbanization on the hydrological cycle. Urban Clim. 2023 , 47 , 101395. [ Google Scholar ] [ CrossRef ]
• Bagyaraj, M.; Senapathi, V.; Chung, S.Y.; Gopalakrishnan, G.; Xiao, Y.; Karthikeyan, S.; Nadiri, A.A.; Barzegar, R. A geospatial approach for assessing urban flood risk zones in Chennai, Tamil Nadu, India. Environ. Sci. Pollut. Res. 2023 , 30 , 100562–100575. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Chen, D.; Cane, M.A. El Nino prediction and predictability. J. Comput. Phys. 2008 , 227 , 3625–3640. [ Google Scholar ] [ CrossRef ]
• Mahala, B.K.; Nayak, B.K.; Mohanty, P.K. Impacts of ENSO and IOD on tropical cyclone activity in the Bay of Bengal. Nat. Hazards 2015 , 75 , 1105–1125. [ Google Scholar ] [ CrossRef ]
• Chang, P.; Fang, Y.; Saravanan, R.; Ji, L.; Seidel, H. The cause of the fragile relationship between the Pacific El Nino and the Atlantic Nino. Nature 2016 , 443 , 324–328. [ Google Scholar ] [ CrossRef ]
• Tolika, K.; Skoulikaris, C. Atmospheric circulation types and floods occurrence; A thorough analysis over Greece. Sci. Total Environ. 2023 , 865 , 161217. [ Google Scholar ] [ CrossRef ]

Click here to enlarge figure

Share and Cite

Radhakrishnan, S.; Duraisamy Rajasekaran, S.K.; Sujatha, E.R.; Neelakantan, T.R. A Comparative Study on 2015 and 2023 Chennai Flooding: A Multifactorial Perspective. Water 2024 , 16 , 2477. https://doi.org/10.3390/w16172477

Radhakrishnan S, Duraisamy Rajasekaran SK, Sujatha ER, Neelakantan TR. A Comparative Study on 2015 and 2023 Chennai Flooding: A Multifactorial Perspective. Water . 2024; 16(17):2477. https://doi.org/10.3390/w16172477

Radhakrishnan, Selvakumar, Sakthi Kiran Duraisamy Rajasekaran, Evangelin Ramani Sujatha, and T. R. Neelakantan. 2024. "A Comparative Study on 2015 and 2023 Chennai Flooding: A Multifactorial Perspective" Water 16, no. 17: 2477. https://doi.org/10.3390/w16172477

Article Metrics

Article access statistics, supplementary material.

ZIP-Document (ZIP, 4689 KiB)

Further Information

Mdpi initiatives, follow mdpi.

Subscribe to receive issue release notifications and newsletters from MDPI journals

Money blog: Iconic Trio chocolate bar could return, hints McVitie's

The Money blog is your place for consumer and personal finance news and tips. Today's posts include NatWest launching the cheapest mortgage on the market, an old Liam Gallagher tweet about ticket pricing and our latest Bring It Back feature - as McVitie's tells us Trio could return.

Tuesday 3 September 2024 15:55, UK

• How your pension could be taxed more as chancellor refuses to rule out hikes
• High-street bank trumps rivals with cheapest five-year mortgage
• Iconic chocolate bar could return, hints McVitie's
• 'Blow' for female founders as agency backtracks on competition awards  

Essential reads

• Basically... Free school meals
• 'This job has saved lives': What's it like selling the Big Issue?
• Best of the Money blog

Tips and advice

• Cheapest holidays dates before Christmas
• Money Problem : 'My dog died but insurance still wants whole year's payment'
• How else to eat Greggs on cheap as O2 Priority scraps freebies

Ask a question or make a comment

Female founders have been dealt a "blow" after Innovate UK delivered just half the number of grants pledged in a funding competition for women business owners.

The Women in Innovation programme was aimed at encouraging women leading small to medium-sized businesses to apply for grants of up to £75,000 each.

The government-backed agency said it would be offering the grants to 50 female founders when it launched the competition earlier this year - but subsequently changed the wording to say "up to 50". 

Only 25 ended up being chosen to receive funding, out of 1,452 applicants.

Dearbump and Femtech founder Emma Jarvis said in a LinkedIn post that the situation will have left many female entrepreneurs "pretty disheartened"

The post  has been shared more than 100 times and has garnered nearly 830 reactions.

"Innovate UK's decision is a blow not just to existing female founders but future ones," Ms Jarvis said. "It's really disappointing to hear that the number of awards was cut in half and that the wording was changed after the results were announced."

She said the "only way forward" was for Innovate UK to honour its original commitment of 50 awards.

Meanwhile, Patricia McGirr, Repossession Rescue founder , said female founders "deserve more than lip service". 

She said Innovate UK's decision "isn't just trimming fat, it's cutting opportunity and ambition".

"This broken promise to the women fuelling our future is a step backward for innovation and a slap in the face to countless women who dare to lead."

And Debbie Porter, managing director at Destination Digital Marketing , said the move was "hard to believe".

"Innovate UK ought to go back over those 1,427 other applications as a matter of priority to fix this situation," she said. 

In a statement to the Money blog, Innovate UK apologised and said its decision was a "mistake". It also said it would honour its original commitment to award 50 applicants with funding.

The added: "We recognise the impact this has had on the many applicants and on the community as a whole, and we apologise wholeheartedly.

"We confirm we will be funding a total of 50 awards."

Our Money blog reporter Jess Sharp spoke to women who are  leading figures in their respective fields for our eight-part Women in Business series earlier this year. You can read some of their stories here...

Chancellor Rachel Reeves has refused to rule out heavier taxation on pensions in the October budget. 

"I'm not going to speculate on what will be in the budget, but I'm absolutely determined to ensure that working people are better off," she told MPs in the House of Commons. 

"This budget will be a budget to fix the foundations of the economy after the mess left by the previous government."

How could your pension be taxed further? Let's have a look at some of the possibilities...

Leading left-wing thinktank The Fabian Society said the government could raise at least £10bn a year by reducing pension tax relief for high earners. 

At the moment, pension tax relief depends on an individual's tax band. 

But Ms Reeves could create a single flat rate of tax relief for all tax bands, the society said.

"First, the rate of income tax relief should be equalised for people on all tax bands - for example at 30% of gross earnings, midway between the 20p and 40p rates of tax," the thinktank said in a report. 

Ms Reeves could also reduce the maximum tax-free lump sum  you can get on retirement from £268,275 to £100,000 or 25% of pension wealth. 

"The Institute for Fiscal Studies estimates that this might eventually save over £2bn per year, which would be targeted entirely at people with high lifetime earnings or assets," the report added. 

Another suggestion was to charge national insurance on private pension incomes . 

The organisation said it would lead to today's affluent pensioners making a higher tax contribution.

Other possibilities could be to levy income tax on all inherited pensions. 

It said pension pots could also be liable to inheritance tax in the same way as other assets. 

What else did the chancellor say today?

Away from refusing to rule out pension tax changes, Ms Reeves also confirmed a cap on corporation tax.

Speaking during Treasury questions, she said the tax would be capped at its current level of 25% to "give business the confidence to grow". 

Corporation tax applies to the annual profits of UK resident companies and branches of overseas companies.

The 25% main rate is payable by companies with taxable profits above £250,000.

A small profits rate applies for companies with profits of £50,000 or below, meaning they will pay 19%.

Up until April 2023, the previous corporation tax main rate was 19%.

After the revival of popular Cadbury's chocolate bar Top Deck earlier this year, we asked you which discontinued treat you would like to see brought back - and we got so many responses that we've decided to make a weekly feature of it called  Bring It Back . 

Every Tuesday, we'll pick one from our comments box and look at why it was so beloved and, crucially, find out whether the companies in question might consider reintroducing them.

This week we're looking at a chocolate bar that became a staple of lunch boxes in the 1980s and '90s - and spawned a TV advert that is among the most fondly remembered of the era: McVitie's Trio.

Sold in multipacks of six, each bar included three segments made up of a caramel layer over biscuit, all covered with milk chocolate.

The product became synonymous with a memorable commercial that featured an animation by artist Bob Godfrey and a play on the traditional Jamaican folk song "Day-O (The Banana Boat Song)".

Its lyrics, which will be familiar to almost anyone who grew up in the 1980s, included the bar's tagline: "I want a Trio and I want one now."

Having discontinued the product in 2003, it briefly returned to shop shelves in 2016 following a Facebook campaign, before vanishing from sale again shortly after.

Hordes of Sky News readers have called for the chocolate bar's revival.

Kellie said: "I'd love to have Trios back! They were yummy. McVitie's really need to start selling them again."

Derek told us: "What a chocolate bar the Trio was! I could eat an entire multipack in one sitting now if given the chance. And that old advert... instantly transported back to childhood just thinking about it."

Samantha said: "I can hear the jingle in my head now! Trios were just delicious chocolate bars... and we want one now!"

When asked by Sky News, a McVitie's spokesperson conspicuously declined to rule out a return for the iconic chocolate treat, saying the company was "constantly listening to what audiences want".

"This helps us to keep innovating and adapting to changing tastes, meaning more biscuits and snacks you love for generations to come," they said.

"For those who miss the caramel taste of Trio, one of our newest and most exciting innovations, McVitie's Gold Billions Wafer, will be your new favourite for on-the-go chocolate moments."

And, tantalisingly for fans of the bar, they added: "Watch this space for more to come..."

Along with the legions of Trio diehards, the Money blog will certainly be doing that - and hope to bring you news of further developments in the crusade in the near future.

Got a craving for any of the products below? Click the links to find out if they've got any chance at making a comeback... 

NatWest has launched the cheapest five-year fixed mortgage deal on the market. 

The 3.71% rate comes with a £1,495 product fee and is available to customers who have a 40% deposit. 

Other lenders have also announced cuts this week, including Barclays and Halifax. 

Yesterday, Barclays reduced its five-year fixed 60% LTV remortgage deal from 4.06% to 3.93%. 

It also announced cuts across its purchase product range, with a five-year fixed 75% LTV deal coming with a 3.95% rate and a £899 product fee. 

Halifax also launched a 3.81% five-year deal to new borrowers yesterday. 

Brokers have welcomed the cuts as "hugely positive" news, and suggested more lenders could follow suit. 

"NatWest's latest rate cut is another clear signal that mortgage lenders are pulling out all the stops to reignite the housing market," Ranald Mitchell, director of Charwin Mortgages, told Newspage.

"This flurry of rate reductions is a positive step towards finding that sweet spot where consumer confidence rebounds, and the property market gets back on track. 

"It's an exciting time for potential buyers, affordability is improving, and the window of opportunity is wide open." 

Justin Moy, the managing director at EHF Mortgages, said: "Lenders are looking to grab some market share by the end of the year.

"Other lenders will likely want to make a similar move over the coming days to remain competitive." 

By James Sillars , business reporter

It's a fairly muted start to the day's trading, again, on financial markets.

The FTSE 100 has opened 10 points higher at 8,373.

Rolls-Royce, the civil aerospace-to-defence firm (not to be confused with the luxury motor car manufacturer), is leading the gainers.

Its shares rallied by 4% early this morning after a 6.5% decline the previous day.

That tumbled was in reaction to the apparent mid-air failure of one of its engines on a Cathay Pacific flight .

Analysts said that the share price recovery was down to an update from  the airline that the fleet affected should be back to full operation by the weekend.

A tweet Liam Gallagher wrote seven years ago criticising the eye-watering price of gig tickets has come back to haunt him.

His message, written in September 2017 about his older brother Noel, who was touring America with his band High Flying Birds at the time, read: "350 dollars to go and see rkid in USA what a c*** when will it all stop as you were LG x"

The tweet has resurfaced after dynamic pricing for Oasis's much-hyped reunion next year left fans - many of whom had spent hours queueing online - stunned after some standard tickets more than doubled in price from £148 to £355 on Ticketmaster due to demand.

X users pointed out the irony upon seeing the 2017 tweet, posting comments including, "Well this is evergreen", "What's your excuse for charging over 368 quid then?" and "Not ageing well, Liam".

Tap here to follow the Daily podcast - 20 minutes on the biggest stories every day

Using a phrase Liam adopts in his own social media comments, another fan wrote simply "BIBLICAL".

Hundreds of people have complained to the Advertising Standards Authority (ASA) over "misleading claims about availability and pricing".

In response, Sir Keir Starmer has said the government will get a "grip" on the issue of surge pricing, with Culture Secretary Lisa Nandy promising a consultation over the transparency and use of dynamic pricing, and the technology around queuing systems, to ensure fans don't get ripped off.

Yesterday we revealed that official reseller Twickets had lowered its fees after criticism from Oasis fans.

Scroll through today's Money blog for: Cheapest dates to go on holiday this year (6.42 post); how do you get free school meals (7.58 post); pay-per-mile tax proposed (7.38 post)

Basically, free school meals are aimed at making sure the country's more vulnerable youngsters don't go hungry while they're learning in their earlier years.

Children of certain ages automatically qualify without having to apply, but the rules differ across the four nations.

Children whose parents claim certain benefits or asylum support may also be eligible - though an application may be needed.

Free school meals without having to apply

In England, outside of London , all state school children in reception to year two automatically qualify for infant free school meals, while in the capital , all state primary school children up to age 11 qualify for the benefit in the 2024-25 academic year.

In Scotland , all state school children up to primary five (around four to nine years old) get the meals automatically. There are plans for this to be extended to pupils in receipt of the Scottish child payment in primary six and seven from February.

In Wales  all primary school children in state schools can get free meals from September.

Families who claim benefits

If your child falls outside the eligibility criteria for automatic free school meals, they'll still be able to benefit in certain circumstances.

Wherever you are in the UK, your child may be able to get free school meals if you get one or more of the following:

• Income support
• Universal credit
• Income-based jobseeker's allowance
• Income-related employment and support allowance
• Support under part six of the Immigration and Asylum Act 1999
• The guaranteed element of pension credit
• Child tax credit
• Working tax credit (Scotland and Northern Ireland)
• Working tax credit run-on England and Wales) – paid for four weeks after you stop qualifying for working tax credit

There's some specific criteria for families by devolved nation, which we'll break down below...

England and Wales

If you're claiming universal credit, your net household income must be less than £7,400 after tax, and not including any benefits.

Those receiving child tax credit must not also be entitled to working tax credit and must have an annual income of less than £16,190.

If you're classed as having no recourse to public funds - a type of condition placed on temporary visas in the UK - and the parents are able to work, they must have a household income of no more than:

• £22,700 for families outside of London with one child
• £26,300 for families outside of London with two or more children
• £31,200 for families within London with one child
• £34,800 for families within London with two or more children

People claiming universal credit in Scotland must have a household monthly income of no more than £796 (£9,552 per year) to qualify for free school meals. 

Families on child tax credit, but not working tax credit, can get the meals if they earn less than £19,995. For those on both benefits, their income must be no more than £9,552.

Northern Ireland

You may be able to claim free school meals in Northern Ireland if you receive universal credit and your post-tax earnings are £15,000 or less per year.

If you get child tax credit or working tax credit, you can still get free school meals on an annual income of up to £16,190.

How can I claim the meals?

In England, Wales and Scotland, you apply to your local council.

The UK government website has a local authority postcode checker here , which directs you to the council running services in your area. There are similar tools on the Scottish and Welsh government websites.

In Northern Ireland, you can use this form to apply directly to the government.

How many children are eligible - and how much does it cost? 

According to the latest data from the Department for Education, 2.1 million pupils were eligible for free school meals in the 2023-24 academic year - 24.6% of pupils. This was a rise from 23.8% the year before.

According to the London mayor's office, it's estimated that school meals cost £13.25 per week - or £2.65 meal - on average.

It says its free school meals offer for all state-educated primary school children in the capital saves parents around £500 per year.

According to a 2023 report from the IFS, the current system of free school meals in England – both means-tested and universal provision – costs the government around £1.4bn a year.

But separate research from the Food Foundation found that expanding free school meal eligibility to all primary school students could generate around £41bn in direct benefits to students and a further £58bn to the wider economy over 20 years.

Read other entries in our Basically series.. .

Tax receipts from petrol and diesel duty bring in £25bn for the Treasury each year - and questions have been raised about what happens as more drivers go electric.

Today, the public transport charity Campaign for Better Transport (CBT) is proposing that drivers of zero-emission vehicles (ZEVs), such as electric cars, should be charged based on how far they travel.

They are asking Chancellor Rachel Reeves to impose the pay-per-mile scheme, saying it's the solution to a "black hole" that will be created by the loss of fuel duty.

The scheme would not apply to drivers of traditionally fuelled cars.

Under the plan, drivers with a ZEV before the implementation date would be exempt, incentivising the switch to electric vehicles.

Previous governments have found the prospect of introducing per-mile charges - known as road pricing - to be too politically toxic.

But CBT claims it would have public support.

Let us know your thoughts in the comments box - and read more on this story here ...

Summer may be edging towards the rear-view mirror, but that doesn't mean Britons are turning their back on sunshine. 

With many looking to sort an autumn holiday, Expedia has taken a look at the best times to fly and book hotels - with savings of up to £120 if you are savvy. 

Its data is based on average daily rates for lodging and flight prices between 22 September and 21 December this year.

When to book flights for

• Cheapest : 22, 23 or 24 September
• Least busy : 10 or 17 December
• Most expensive : 19, 20 or 21 December
• Busiest : 20 and 21 October

"For the best deals, travellers should look to book their flights 14 to 20 days before travel, saving them on average £120 compared to booking 91 days or more out, or saving £60 compared to booking 60-90 days out," Expedia says. 

"Target the 22-29 September for travel, when average ticket prices (ATPs) for flights are shaping up to be nearly £100 cheaper than the autumn average, and £50 cheaper than summer ATPs."

When to  book a hotel

• Cheapest : 20 November or 11 December
• Most expensive : 14 or 21 October
• Busiest : 23 October or 25 September

"For hotel stays, target the 3-9 November, when average daily rates are £15 cheaper per night than the seasonal average and summer stays," Expedia says. 

The holiday booking site says the most popular autumn destinations have remained largely the same as last year based on the largest number of hotel searches...

• New York, USA
• Paris, France
• Edinburgh, Scotland
• Amsterdam, Netherlands
• Manchester, UK
• Tenerife, Spain
• Birmingham, UK
• Rome, Italy

Despite this, Expedia says savvy Britons are searching out "under the radar" getaway spots.

"Flight searches have surged for Brits looking to discover new, under-the-radar European cities this autumn, such as Tirana (+95%) in Albania and Bucharest (+70%) in Romania, as Brits look to stretch their budgets further by looking outside the popular city break hotspots."

The top 10 destinations with the biggest search increases are:

• Saint Malo, France
• Didim, Turkey
• Syracuse, Italy
• Beijing, China 
• Palermo, Italy
• Tromso, Norway 
• Brescia, Italy 
• Poznan, Poland
• Tangier, Morocco
• Ischia, Italy

The Money blog will return shortly - meantime, why not scroll through some of our best and most popular features below...

Be the first to get Breaking News

Install the Sky News app for free