Carbon storage and dynamics in cryosphere: Progress and challenges

Climate warming threatens the cryosphere across cold regions, which include glaciers, permafrost, snow cover, and sea ice. Permafrost thaw has occurred in recent decades in Arctic regions, as well as in alpine regions. The potential release of a large amount of organic carbon could further accelerate global warming. Here we summarize recent progress related to the storage, source, composition, stabilization, and emission of permafrost carbon in the Arctic and Third Pole regions. By combining previous data syntheses and model estimations, we conclude that the soil organic carbon storage for the 0–300 cm layer of soil is approximately 985.8 ± 98.7 Pg C in the Northern Circumpolar permafrost regions and 23.5 ± 11.1 Pg C in the Qinghai-Tibet permafrost region. The projection of the ecosystem model shows that the carbon emissions from permafrost due to warming is expected to reach as high as 240 Pg C by 2100, with an average of 92 ± 17 Pg C. Finally, we present some priorities for permafrost carbon research, including the long-term and continuous observation of carbon dynamics, improvement of the ecosystem model to reduce uncertainties in projections, and the application of advanced techniques such as machine learning or deep learning, to achieve a more accurate assessment of the response of carbon dynamics to climatic warming in the future.