Thawing permafrost contributed to past increases in atmosphere carbon dioxide levels
Thawing permafrost may have played a much larger role in the rise of carbon dioxide after the last Ice Age than previously believed. A new study led by researchers at the Bolin Centre suggests that up to half of the pre-industrial increase can be traced to carbon released from thawing soils in the northern hemisphere. These changes mainly occurred between 17,000 and 10,000 years ago.
Earlier research pointed mainly to the oceans, which release more CO₂ as they warm. But this study shows that thawing permafrost released vast amounts of organic material stored in frozen soils and vegetation, significantly adding to the atmospheric carbon dioxide levels.
By analysing pollen data spanning over the last 21,000 years in combination with climate model simulations, the researchers reconstructed changes in vegetation and soil carbon storage over time. They found that CO₂ levels rose from about 180 ppm during the Ice Age to 270 ppm in the early Holocene, 10,000 years ago, partly driven by permafrost thaw.
Today, however, human activity has rapidly driven CO₂ to around 420 ppm, with no natural processes in sight to restore balance. Future thawing of permafrost could therefore add even more carbon to the atmosphere.
Last updated: September 30, 2025
Source: Inês Gonçalves Varela Jakobsson