In a reversal from previous years, U.S. carbon emissions rose 2.4% in 2025 compared with the year before. NBC News reports: * The increase in greenhouse gas emissions is attributable to a combination of a cool winter, the explosive growth of data centers and cryptocurrency mining and higher natural gas prices, according to the Rhodium Group, an independent research firm. Environmental policy rollbacks by President Donald Trump’s administration were not significant factors in the increase because they were only put in place this year, the study authors said. Heat-trapping gases from the burning of coal, oil and natural gas are the major cause of worsening global warming, scientists say.

American emissions of carbon dioxide and methane had dropped 20% from 2005 to 2024, with a few one- or two-year increases in the overall downward trend. Traditionally, carbon pollution has risen alongside economic growth, but efforts to boost cleaner energy in recent years decoupled the two, so emissions would drop as gross domestic product rose. But that changed last year with pollution actually growing faster than economic activity, said study co-author Ben King, a director in Rhodium’s energy group. He estimated the U.S. put 5.9 billion tons (5.35 billion metric tons) of carbon dioxide equivalent in the air in 2025, which is 139 million tons (126 million metric tons) more than in 2024.

The cold 2025 winter meant more heating of buildings, which often comes from natural gas and fuel oil that are big greenhouse gas emitters, King said. A significant and noticeable jump in electricity demand from data centers and cryptocurrency mining meant more power plants producing energy. That included plants using coal, which creates more carbon pollution than other fuel sources. A rise in natural gas prices helped create an 13% increase in coal power, which had shrunk by nearly two-thirds since its peak in 2007, King said.