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Large loss of CO2 in winter observed across the northern permafrost region

The study published in Nature Climate Change warns that winter carbon dioxide (CO2) loss from the world’s permafrost regions could increase by 41% if human-caused greenhouse gas emissions continue on their current pace.

Recent warming in the Arctic greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide CO2. However, the amount of CO2 released in winter is not known and has not been well represented by ecosystem models or empirically based estimates.

The study synthesizes regional in situ observations of CO2 flux from Arctic and boreal soils to assess current and future winter carbon losses from the northern permafrost domain. It estimates a contemporary loss of 1,662 TgC per year from the permafrost region during the winter season (October–April). This loss is greater than the average growing season carbon uptake for this region estimated from process models (−1,032 TgC per year). Extending model predictions to warmer conditions up to 2100 indicates that winter CO2 emissions will increase 17% under a moderate mitigation scenario —Representative Concentration Pathway 4.5 — and 41% under business-as-usual emissions scenario —Representative Concentration Pathway 8.5.

The results of the study provide a baseline for winter CO2 emissions from northern terrestrial regions and indicate that enhanced soil CO2 loss due to winter warming may offset growing season carbon uptake under future climatic conditions.

This study was supported by NASA ABoVE and conducted in coordination with the Woods Hole Research Centre, the Permafrost Carbon Network and more than 50 collaborating institutions.

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