Arctic warming has split Siberia into two climate regimes that could wake a methane giant

Arctic warming is reshaping Siberia into two distinct climate regimes, one growing wetter and the other drier, and both are driving a sharp rise in methane emissions from the region’s vast frozen ground, a new study finds. The research, published in the journal Science, draws on more than a decade of satellite and atmospheric data showing that annual methane emissions from Siberia climbed by roughly 5 percent a year between 2010 and 2023. Scientists involved say the trend threatens to erode a meaningful share of the methane cuts the world needs to meet its climate targets.

A River That Splits Siberia Into Two Climates

According to the research, the Yenisei River roughly marks the boundary between two separate environmental states researchers call climate regimes. West of the river, rising heat and moisture carried in from the North Atlantic Ocean by the Scandinavian atmospheric circulation pattern, a system with a main center over Scandinavia and weaker opposing centers over Western Europe and eastern Russia, are making the region wetter. East of the river, a pattern known as the Arctic Oscillation is instead driving persistent high-pressure systems that reduce cloud cover, intensify heat waves, and leave the landscape drier and more prone to wildfire. The two patterns respond differently to the same underlying Arctic warming, which is why the region is splitting into opposite climate trajectories rather than uniformly drying or wetting.

Western Siberia’s Permafrost Turns to Mush

Siberia holds roughly 46 percent of the Northern Hemisphere’s permafrost, ground that has stayed frozen for at least two consecutive years and traps carbon that has accumulated in the soil for thousands of years. In the western half of the basin, the added warmth and moisture are triggering extensive permafrost thaw, unlocking that stored carbon so microbes can convert it into methane through a process called methanogenesis. The thawing ground often collapses into bumpy landscapes of mounds and hollows as the ice within it melts unevenly, a visible sign of the microbial activity happening underground. Researchers describe this pathway as the dominant source of the region’s rising methane output, distinct from the mechanism driving emissions on the other side of the river.

Eastern Siberia Burns Instead of Thaws

Across the Yenisei in eastern Siberia, the story is different. The Arctic Oscillation’s influence brings hotter, drier summers and a sharp rise in wildfire activity, particularly since 2019, as persistent high-pressure systems suppress cloud formation and dry out vegetation and soil. Those fires release methane directly into the atmosphere as vegetation and soil organic matter burn, but researchers say they also destabilize the permafrost beneath the burned ground, stripping away the insulating surface layer and setting up conditions for further methane release long after the flames are out. The study’s authors describe eastern Siberia as the faster-warming half of the basin, which they say helps explain why wildfire-driven emissions there have grown so quickly in recent years.

A Decade of Satellite Data Behind the Numbers

Because Siberia is vast, sparsely instrumented, and largely inaccessible to researchers amid the Russia-Ukraine war, the international team relied on satellite observations rather than ground sensors to track the trend. Data from the Japanese Greenhouse gases Observing Satellite, analyzed through a methane flux inversion system that narrowed uncertainty to roughly 10 percent, allowed scientists from the University of Edinburgh’s National Centre for Earth Observation, the University of Leicester, and the Chinese Academy of Sciences to map emissions across the region despite the lack of on-the-ground access. Because Siberia receives little sunlight in winter, the satellites’ readings are least reliable during the coldest months, but the researchers note most methane release already happens in spring and summer, when sunlight and thawing activity both peak.

Emissions Growth Rivals Global Wetland Trends

Over the 2010-2023 study period, Siberia’s annual methane emissions grew by about 13.2 million tons, or roughly 12 million metric tons, an increase that nearly mirrors the pace of methane growth from wetlands worldwide. Siberia currently accounts for only around 5 percent of global methane emissions, but researchers describe it as one of the fastest-growing natural sources of the gas on the planet. Their models suggest emissions from the region could climb by an additional 25 million tonnes a year by 2050, a volume comparable to the annual methane output of some major industrialized nations, which would offset roughly 20 percent of the anthropogenic methane reductions needed this decade to keep global warming close to 1.5 degrees Celsius.

A “Sleeping Giant” That Could Still Wake

Study co-author Paul Palmer, a professor at the University of Edinburgh’s School of GeoSciences, described Siberia’s frozen carbon reserves as a sleeping giant that continued warming risks waking into a far larger source of greenhouse gases. Researchers identified eastern Siberia as the main driver of the projected increase, since it is warming faster than the western half of the basin and has already seen extreme wildfires spike. Whether that trend keeps accelerating, the study notes, will depend partly on how much vegetation remains available to burn in future fire seasons, and on whether repeated burning keeps chipping away at the permafrost layer that has kept Siberia’s oldest carbon locked away for millennia.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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