Permafrost—permanently frozen ground in the coldest regions of the Earth—has stored large amounts of organic carbon from dead plants and animals for thousands of years. As climate change progresses, however, this ground is increasingly thawing. In the process, the bound carbon is released and converted by microorganisms into methane, a particularly potent greenhouse gas.
A new study funded by the U.S. National Science Foundation now shows that previously little-studied, unfrozen layers within permafrost in arid regions—so-called taliks—produce a surprisingly large amount of methane. This discovery raises new questions about the role of permafrost in the global climate system and gives rise to concern that additional methane emissions could further accelerate climate change in the fragile Arctic environment.
Researcher Katey Walter Anthony and her team from the University of Alaska Fairbanks investigated methane emissions from taliks in the Yedoma uplands. Yedoma is an Ice Age permafrost type known for its well-preserved mammoth remains and extends from northeastern Siberia across Alaska to Canada. Measurements showed that dry upland taliks exhibit unexpectedly high methane emissions—almost three times higher than those from northern wetlands.
Particularly surprising: unlike permafrost regions studied so far, these upland taliks release significantly more methane in winter than in summer. Given that the Arctic is warming almost four times faster than the global average, this additional methane source could trigger a self-reinforcing cycle of rising temperatures and further permafrost thaw.
The findings underscore the urgency of more fully incorporating permafrost regions—especially dry upland areas—into climate models in order to better assess the future development of the global climate system.
Heiner Kubny, PolarJournal