UN Says U.S. Emissions Push World Toward Hotter Future

The world is on track for a hotter climate than experts projected last year, with the United States a major reason why, according to a new United Nations report published Wednesday. The United Nations Environment Programme update says Earth will likely warm another 2.2 degrees Fahrenheit (1.2 degrees Celsius) above current temperatures if countries meet their promised emissions cuts. That’s about two-tenths of a degree Fahrenheit more than the same science team projected last year.

The Policy Shift Behind the Forecast

The report points to two reasons for the worsening outlook. First, the United States formally withdrew from the Paris Agreement. Second, researchers revised their estimates of historical emissions. The U.S. also stands alone among the top 20 major economies in one key respect: its emissions rose last year, while every other top 20 economy either cut carbon pollution or slowed the growth of emissions from burning coal, oil and gas.

America’s emissions increase reached 133 megatons of CO2 equivalent. Rising electricity demand and a rebound in coal power generation drove that increase, the report says. Of the 124 countries whose emissions grew in 2025, the United States accounted for 70% of the added 189 million tons of carbon dioxide. Most European nations, in contrast, joined the 63 countries that reduced emissions.

What Outside Experts Are Saying

Bill Hare, CEO of Climate Analytics, which tracks countries’ climate plans, didn’t hold back. He said the United States is “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 added that the country was “looking at the fire, denying there is a fire, and then pouring more petrol on it.” He wasn’t part of the U.N. report, but he and several other outside scientists told the Associated Press that its science was sound.

The numbers under current plans look sobering. If countries carry out the climate plans they submitted, the globe would be 2.6 degrees Celsius (4.7 degrees Fahrenheit) hotter than pre-industrial times by 2100. Without national promises, warming would reach 2.8 degrees Celsius (5 degrees Fahrenheit), matching last year’s projection. Both outcomes exceed the 2015 Paris climate pact’s goal of keeping warming under 2 degrees Celsius, and preferably at 1.5 degrees Celsius.

A Goal Officials Now Concede They Can’t Reach

The planet already sits about 1.4 degrees Celsius (2.5 degrees Fahrenheit) above pre-industrial levels. United Nations officials acknowledged earlier this year, and again in the report, that there’s no way to hold warming to the 1.5-degree goal they once embraced. Their new target is about 1.8 degrees Celsius (3.2 degrees Fahrenheit), with a plan to remove enough carbon dioxide from the air afterward to bring temperatures back down to 1.5 degrees.

United Nations Secretary-General António Guterres said the world is falling “dangerously short” of even those goals. “But we have the tools to change course and pull back from the brink,” he said. UNEP Executive Director Inger Andersen said the world must cut global carbon emissions by 18% by 2030 and 69% by 2040. “That is the only way that we can get back to a semblance of a reality that is still largely manageable without major impacts.”

Some voices in the debate stressed the urgency. Climate scientist Adelle Thomas, vice chair of a United Nations scientific assessment on climate impacts, said, “We know what needs to be done. We have the tools to do it. And delay only makes the challenge more dangerous and more expensive for all.” Thomas wasn’t part of the study.

The Price Tag

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. Michael Mann, a University of Pennsylvania climate scientist, said that increase would shave about $1.2 trillion from the global economy. Johan Rockstrom, director of the Potsdam Institute for Climate Impacts Research in Germany, argued that the American effect is probably larger than the United Nations calculates. Other nations may ease their own efforts if the world’s largest historical climate polluter does little, he said.

Hare described the human cost of that small increase in stark terms. An extra one-tenth of a degree, he said, would push an additional 140 million people “into dangerously hot conditions” and raise the odds of collapse for the Amazon rain forest or the ice sheets in Greenland and Antarctica.

Mohamed Adow, director of Power Shift Africa, said the retreat “isn’t just a political embarrassment. It has real consequences for the planet and for millions of people around the world.” Malte Meinshausen, an Australian climate scientist, took a harder line. “The rest of the world is exhausted when it comes to counting the damage that the U.S. is willingly doing to allies, multilateral structures, economic cooperation, disaster relief,” he said. “The rest of the world should probably continue to focus even less on the U.S.”

Seth Borenstein wrote the report for The Associated Press from Washington, D.C. The AP said multiple private foundations support its climate and environmental coverage, and the news agency alone is responsible for its content.

Why This Matters:

The fiscal stakes are concrete. Michael Mann’s estimate that a one-tenth-of-a-degree rise could cost the global economy about $1.2 trillion puts a dollar figure on what policy choices can mean for markets and households alike. The report also shows how one nation’s energy decisions ripple outward: Johan Rockstrom suggested other countries may slacken their own efforts. For those who believe in market-based solutions and steady, realistic energy planning, the data raises a hard question. Rising electricity demand and coal generation drove America’s emissions increase, the report says, suggesting energy reliability and affordability remain central to any credible climate strategy. The gap between submitted national plans and the Paris goals, now conceded by the United Nations itself, tests whether ambitious international targets can survive contact with domestic economic realities. Whether the world can close that gap without damaging the growth that funds progress remains the unanswered question at the center of this report.