Accelerated rise in wildfire carbon emissions from Arctic continuous permafrost.

ABSTRACT

Wildfires over permafrost put perennially frozen carbon at risk. However, wildfire emissions from biomass burning over the diverse range of permafrost regions and their share in global wildfire emissions have not been revealed. The results showed a dramatic increase in wildfire carbon emissions from permafrost regions over the period 1997-2021. The share of permafrost in global wildfire CO2 emissions increased from 2.42% in 1997 to 20.86% in 2021. Accelerating wildfire emissions from continuous permafrost region is the single largest contributor to increased emissions in northern permafrost regions. Fire-induced emissions from 2019 to 2021 alone accounted for approximately 40% of the 25-year total CO2 emissions from continuous permafrost regions. The rise in wildfire emissions from continuous permafrost regions is explained by desiccation within a 5-10 cm soil depth, where wildfires combust belowground fuel. These findings highlight the acceleration of fire-induced carbon emissions from continuous permafrost regions, which disturb the organic carbon stock and accelerate the positive feedback between permafrost degradation and climate warming, thus stimulating permafrost towards a climatic tipping point.