Wildfires offset the increasing but spatially heterogeneous Arctic–boreal CO2 uptake

Le résumé fourni par la source

Abstract The Arctic–Boreal Zone is rapidly warming, impacting its large soil carbon stocks. Here we use a new compilation of terrestrial ecosystem CO 2 fluxes, geospatial datasets and random forest models to show that although the Arctic–Boreal Zone was overall an increasing terrestrial CO 2 sink from 2001 to 2020 (mean ± standard deviation in net ecosystem exchange, −548 ± 140 Tg C yr −1 ; trend, −14 Tg C yr −1 ; P < 0.001), more than 30% of the region was a net CO 2 source. Tundra regions may have already started to function on average as CO 2 sources, demonstrating a shift in carbon dynamics. When fire emissions are factored in, the increasing Arctic–Boreal Zone sink is no longer statistically significant (budget, −319 ± 140 Tg C yr −1 ; trend, −9 Tg C yr −1 ), and the permafrost region becomes CO 2 neutral (budget, −24 ± 123 Tg C yr −1 ; trend, −3 Tg C yr −1 ), underscoring the importance of fire in this region.

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