U.S. Coal Policy Raises Global Warming Costs

The United States accounted for 70% of the additional carbon dioxide reported in 2025 by countries whose emissions rose, while a new United Nations report says the world is on track for more warming than it projected last year. In its Wednesday update, the United Nations Environment Programme says Earth will likely warm another 1.2 degrees Celsius above current temperatures, even if countries meet their promised emissions cuts. That’s 0.1 degrees Celsius more than last year’s projection.

Who Drives the Increase

The report links its worse outlook to the United States’ formal withdrawal from the Paris Agreement and updated estimates of historical emissions. U.S. emissions rose by 133 megatons of carbon dioxide equivalent last year, as electricity demand increased and coal power generation rebounded.

Among the 124 countries that increased emissions in 2025, excluding 63 that reduced them, the United States accounted for 70% of the added 189 million tons of carbon dioxide. Most European nations cut emissions. The other top 20 major economies either reduced carbon pollution or slowed the growth of emissions from burning coal, oil and gas, the report said.

Australian climate scientist Bill Hare, CEO of Climate Analytics, which measures countries’ climate plans, said the United States is going “hell-for-leather trying to block renewables while actively promoting and subsidizing dirty coal — and its diplomacy is trying to make other countries also pull back on action.” Hare wasn’t part of the U.N. report, but he and several other outside scientists said its findings were scientifically sound.

Anne Olhoff, the report’s lead author and director of UNEP Copenhagen Climate Centre, said the U.S. policy change will likely add one-tenth of a degree Celsius to global temperatures by the end of the century. Johan Rockstrom, director of the Potsdam Institute for Climate Impacts Research in Germany, said the U.S. effect is probably larger than the United Nations calculates, since other nations may ease their efforts if the world’s largest historical climate polluter does little to fight global warming.

The Cost of the Policy

Mohamed Adow, director of Power Shift Africa, said the added tenth of a degree means “more dangerous heat waves, more destructive floods, more failed harvests and more lives lost.” He said vulnerable communities in Africa already live on the front lines of the climate crisis. Every fraction of a degree matters.

Hare said the added warming would push an additional 140 million people “into dangerously hot conditions” and raise the odds of the Amazon rain forest or the ice sheets in Greenland and Antarctica collapsing. University of Pennsylvania climate scientist Michael Mann said it would cost the world and shave about $1.2 trillion from the global economy.

The report projects that submitted national climate plans would leave the globe 2.6 degrees Celsius hotter than pre-industrial times by 2100. Without those promises, the current path would bring warming to 2.8 degrees Celsius above the last half of the 19th century, matching last year’s projection. Both outcomes exceed the 2015 Paris climate pact’s goal of keeping warming below 2 degrees Celsius, preferably 1.5 degrees.

Targets and Limits

The world is now about 1.4 degrees Celsius above pre-industrial levels. United Nations officials have acknowledged they can’t limit warming to the 1.5-degree goal they had embraced. They’re instead hoping to hold warming to about 1.8 degrees Celsius, then remove enough carbon dioxide from the air to bring temperatures back down to 1.5 degrees.

UNEP Executive Director Inger Andersen said global carbon emissions must fall 18% by 2030 and 69% by 2040. “It is the only way that we can get back to a semblance of a reality that is still largely manageable without major impacts,” she said.

United Nations Secretary-General António Guterres said the world is falling “dangerously short” of those goals, “but we have the tools to change course and pull back from the brink.” Climate scientist Adelle Thomas, vice chair of a United Nations scientific assessment on climate impacts, said delay makes the challenge “more dangerous and more expensive for all.” The report was published on October 21, 2026.