Thawing Arctic permafrost could add about a quarter degree Celsius of warming by the end of the century, two studies say. Political and scientific estimates of future warming usually leave out greenhouse gases released from frozen ground. Scientists say the projected contribution could warm Earth about as much as a major industrialized country such as the United States or the whole of Europe.
That warming would come on top of emissions from people burning coal, oil and natural gas. A September study co-authored by Sue Natali of the Woodwell Climate Research Center found that permafrost thaw and other warming-induced emissions from fires and changes to wetlands and lakes are likely to increase warming by 20% by the end of the century.
What climate estimates leave out
The United Nations estimate that the world will warm 2.6 degrees C (4.7 degrees F) above pre-industrial levels by the end of the century without policy changes leaves out a few tenths of a degree from permafrost thaw, Natali and Gustaf Hugelius said. Those estimates don’t include all the additional greenhouse gases scientists expect from thawing ground.
Andrew Weaver, a University of Victoria climate scientist who first calculated the half-degree of expected permafrost warming in a 2012 study, said the amount may be small and not a “scenario of doom.” But it’s something “that we’re going to have to deal with” on top of other warming.
At Smith Lake in Alaska, ecologist Ted Schuur saw methane bubbles rise from the muck. As the ground thaws, plants and animals trapped in permafrost decompose and release methane and carbon dioxide. The Arctic is warming four times faster than the rest of the globe, and permafrost holds three times as much carbon as is currently in the atmosphere, Schuur said.
“Once you start leaking this carbon out, there’s so much in the ground that it’s not going to shut off,” said Schuur, an ecologist at Northern Arizona University. He called the process one of climate change’s “scary tipping points.” “Essentially every year is setting a permafrost record,” he said.
A changing ground beneath Arctic communities
Permafrost is ground that stays frozen below 32 degrees Fahrenheit (zero degrees Celsius) for at least two years, and often for centuries or millennia. It occurs in Alaska, Canada, Siberia, Antarctica and high mountain areas elsewhere. Frozen ground has supported homes, roads and pipelines in Arctic regions, but scientists say it’s becoming less reliable.
Thaw can also make the ground collapse and sink, Natali said. In Galbraith on Alaska’s North Slope, scientists recently saw a craterlike hole 10 feet (3 meters) deep. These depressions, called slumps, form when ice melts and land collapses, releasing methane. A Woodwell team has identified more than 40,000 slumps across the Arctic using satellites, according to scientist Kyle Arndt.
In Kotzebue, Alaska, thawing permafrost warped a road. In Newtok, Alaska, coastal permafrost was melting. Photographs documenting those conditions were dated Sept. 26, 2025, and Aug. 16, 2024, respectively.
Gustaf Hugelius, a permafrost expert at Stockholm University, called the system “really like a sleeping giant.” For thousands of years, the Arctic acted as a carbon sink: plants in cold regions drew heat-trapping gas from the air and stored it in frozen ground. A few years ago, warming shifted that balance. Thawing ground then began releasing more heat-trapping gases than it absorbs, said Duncan Menge, a Columbia University ecologist.
University of Alaska Fairbanks geophysicist Vladimir Romanovsky said that when he began studying permafrost in the 1970s, “everybody believed permafrost was very stable. People thought it was forever.” He said that’s no longer the case. “It took some thousands and tens of thousands of years to sequester this carbon into permafrost,” Romanovsky said. “You need a new ice age to put back this ice into the ground.”