Den arktiska permafrostens minskning och dess positiva feedback till den globala uppvärmningen

Sammanfattning: 24 % of the Northern Hemisphere’s landmass is underlain by permafrost. 1 700 billion tonnes of organic carbon (C) is stored in the permafrost, and the ongoing climate change lead to permafrost thawing and carbon release. This study examines the extent of thawing permafrost and the estimated carbon emissions as a consequence of permafrost thawing. The results show an estimated decrease of near-surface permafrost up to 81% before 2100 due to an increase of the average global temperature. Thawing permafrost releases CO2 and CH4 to the atmosphere, which amplifies the greenhouse effect and creates a positive feedback to global warming. The magnitude of the positive feedback is uncertain but an average of 178 Pg C is expected to release to the atmosphere by 2100 if the anthropogenic emissions continues. A potential increase in biomass due to favorable growing conditions is not expected to offset the carbon emissions.