Climate Matters•October 16, 2025
Ten years ago, nearly every country in the world signed on to the landmark Paris Agreement to limit global warming and reduce the escalating risks to people, ecosystems, and economies.
According to new global analysis, the future of extreme heat — the deadliest form of weather — hinges on the Paris Agreement.
Current pledges to reduce heat-trapping pollution fall short of the Paris Agreement goals and would result in a dangerously hot planet by 2100 — with double the number of hot days people face today.
But if the Paris Agreement hadn’t been signed, the world would be headed toward a far riskier future, with triple the number of hot days people face today.
Current Paris Agreement pledges lead to a future of vastly more dangerous heat. But meeting these pledges is also essential to curb far worse future heat risks across the globe and in the U.S.
The last 10 years have been record hot for the planet.
This unprecedented warming is the direct result of human activities — primarily burning fossil fuels (coal, oil, and methane gas) for energy, transportation, and more.
The effects of global warming — on hurricanes, wildfires, dangerous heat, and more — worsen with every additional bit of heat-trapping pollution.
The recognition of these risks to health and safety, economies, and ecosystems prompted nearly every country in the world to sign on to the 2015 Paris Agreement to keep global warming well below 2°C (3.6°F) relative to pre-industrial temperatures with an aspirational goal of 1.5°C (2.7°F).
Current Paris Agreement pledges to reduce heat-trapping pollution put the planet on track for at least 2.6°C (4.7°F) of global warming this century — overshooting the 1.5°C and 2°C goals and leading to a vastly more dangerous climate. And there’s still a glaring gap between these risk-reducing goals and the actions required to realize them.
Critically, though, there are signs of progress under the Paris Agreement. Policies in place prior to 2015 had the planet on track to heat up a catastrophic 4°C (7.2°F) this century.
In other words, current pledges would both fail to reach the Paris Agreement goals while also avoiding the far higher risks that people and ecosystems would face if the agreement had never been signed.
It’s important to acknowledge that these warming projections are anything but guaranteed. Full implementation of current pledges would require far more action — and fast (with each country enacting and sustaining policies to carry out their pledges). Progress could be eroded further by the planned January 2026 withdrawal of the U.S. – the country with the highest cumulative total emissions of heat-trapping CO2 – from the Paris Agreement.
The changing frequency of extreme heat — the deadliest form of weather — shows that countries’ current pledges represent both essential progress and a critical shortfall on the Paris Agreement’s goal of a safer future.
According to new global analysis, the future of extreme heat hinges on the Paris Agreement.
With current Paris Agreement pledges (2.6°C of warming by 2100), countries would experience an average of 115 hot days per year by the end of this century. This represents a dangerously hot planet with double the number of hot days people face today.
The future would be even riskier if the Paris Agreement had never been signed (4°C of warming by 2100). In this pre-Paris scenario, countries around the world would experience an average of nearly 172 hot days per year by the end of this century. That’s nearly six months of extreme heat annually, or about triple the number of hot days people face today.
Learn more: read the report and download data for 207 countries and all U.S. states.
These results also show that full implementation of countries’ current pledges, while insufficient to meet Paris Agreement goals, is essential to curb far worse future heat risks across the globe — including in the U.S.
In the U.S., the average person currently experiences about two months (58 days) worth of hot days annually.
If current Paris Agreement pledges are fully met, the country would see three months (88 days) worth of hot days annually by the end of this century — or 50% more than we experience today.
If the Paris Agreement had never been signed, that would be about four months (118 days) — or double the number of hot days people in the U.S. experience today.
Download data to explore results for all U.S. states.
In other words, full implementation of current Paris Agreement pledges would avoid an additional month of future hot days — and curb the related risks.
Heat is the leading cause of weather-related deaths in the U.S. In 2023, a record 2,325 people died from heat in the U.S. alone, though such figures are widely thought to be an undercount.
In the U.S., state-level climate action is increasingly important. Is yours among the 24 states with official clean energy goals, the 22 states and two territories in the U.S. Climate Alliance, or the 32 states with Climate Action Plans? Search State Climate Policy Maps or the Database of State Incentives for Renewables & Efficiency for the status of climate action in all 50 states. State Climate Scorecards track each state’s progress toward official climate goals, broken out by sector.
A Decade of Growth for U.S. Solar and Wind shows that the U.S. produced enough solar and wind power in 2024 to power 70 million homes — reflecting a 10-year growth curve in both technologies at the state and national levels.
Clean Energy Investment in Every State shows which states and clean energy technologies have seen the most investment so far.
Climate Solutions in Every State reviews options to quickly reduce emissions in each U.S. state’s top-emitting sector.
To request an interview with a Climate Central scientist about this analysis, please contact Abbie Veitch, aveitch@climatecentral.org.
Submit a request to SciLine from the American Association for the Advancement of Science or to the Climate Data Concierge from Columbia University. These free services rapidly connect journalists to relevant scientific experts.
Browse maps of climate experts and services at regional NOAA, USDA, and Department of the Interior offices.
Explore databases such as 500 Women Scientists, BIPOC Climate and Energy Justice PhDs, and Diverse Sources to find and amplify diverse expert voices.
Reach out to your State Climate Office or the nearest Land-Grant University to connect with scientists, educators, and extension staff in your local area.
The two projected global warming levels analyzed in this report (2.6°C, and 4.0°C) are derived from the U.N. Emissions Gap Reports of 2015 and 2024. The 2015 report, published around the time the Paris Agreement was adopted, reported a “baseline” projected warming of about 4°C. The 2024 report projected a warming of between 2.6°C and 3.1°C given current nationally determined contributions and associated national policies (herein, referred to as “pledges”).
In this analysis, “hot days” are days when maximum temperatures are hotter than 90% of local temperatures over the 1991-2020 period.
To calculate the frequency of “hot days,” we first used ERA5 data to calculate the 90th percentile temperature of all maximum daily temperatures at each grid cell over the 1991-2020 time period. We then used the World Bank’s Climate Change Knowledge Portal to access 21 ERA5-debiased CMIP6 models, from which we computed a multi-model average of the number of days above the 90th percentile for each modeled year from 1950-2100.
To calculate country-level and state-level averages, we took the final number of days above the 90th percentile and averaged them across each country, weighted by population density in each ERA5 grid cell.
A full, detailed methodology is available in the report: https://climatecentral.org/report/10th-anniversary-paris-agreement
