Permafrost, ground frozen year-round across 20 million square kilometers in Siberia, Canada, Alaska and parts of Europe, contains approximately 1,500 gigatons of carbon—three times more than all living vegetation on Earth. According to Gustaf Hugelius, a climate professor at Stockholm University’s Bolin Centre, the thawing of these regions presents a significant threat to global climate stability.
As atmospheric temperatures rise from human emissions, permafrost begins to thaw, exposing ancient plant material to microbial decomposition. Microorganisms break down the organic matter, releasing carbon dioxide and methane into the atmosphere, creating a self-reinforcing warming cycle. Once permafrost crosses a critical threshold, the landscape undergoes permanent changes. Melting subsurface ice causes ground collapse, creating thermokarst formations such as lakes, wetlands, and river valleys. These new landforms fundamentally alter soil hydrology and thermal properties, making the system irreversible on human timescales. The permafrost region is unlikely to experience a single global tipping point unless warming reaches 6 degrees Celsius, but multiple localized tipping points are already occurring in succession across the region.
Under warming scenarios of 1.8 to 3.6 degrees Celsius by the end of this century, permafrost could release 200 to 300 gigatons of carbon dioxide equivalents—comparable to current emissions from the European Union or United States. Whether permafrost releases methane or carbon dioxide depends on whether thawed areas become dry or wet environments. Dry landscapes produce carbon dioxide through oxidation, while waterlogged areas generate methane, which is approximately 30 times more potent as a greenhouse gas over short timescales but breaks down within 10 to 15 years.
A significant lag exists between atmospheric warming and permafrost response due to insulation from vegetation and peat layers. Consequently, areas in northern Sweden and Finland are already committed to thawing regardless of future climate action. However, larger permafrost regions in Siberia and Canada could potentially remain intact if global temperature increases are limited through effective climate policy negotiations.
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