Contribution of high-latitude permafrost regions in the Northern Hemisphere to global wildfire carbon emissions

Abstract

Wildfires are major disturbances in permafrost ecosystems, with increasing frequency and intensity in recent years. In permafrost regions, wildfires not only burn surface and subsurface organic matter but also accelerate permafrost thawing, releasing significant amounts of greenhouse gases such as carbon dioxide and methane into the atmosphere. However, the contribution of high-latitude permafrost regions in the Northern Hemisphere to global wildfire carbon emissions remains poorly understood. This study integrates remote sensing data and ground observations to analyze the contributions of aboveground and belowground fuel combustion in high-latitude permafrost regions to global wildfire carbon emissions from 2002 to 2020, as well as the spatiotemporal variations in these contributions. Our findings indicate that permafrost regions contribute approximately 11.96% of global wildfire carbon emissions, with aboveground emissions accounting for approximately 3.94% of global aboveground emissions and belowground emissions contributing approximately 63.57% of global belowground emissions. The contribution of high-latitude permafrost regions to global emissions peaked in July and August, whereas the continuous permafrost zones (areas with more than 90% permafrost coverage) showed the most significant increase in June and July. The contributions of both aboveground and belowground emissions from high-latitude permafrost regions to global wildfire emissions have been increasing, primarily due to the reduction in global wildfire emissions, in contrast with the rising emissions from wildfires in high-latitude permafrost regions. This study highlights the significant role of wildfires, particularly the combustion of belowground biomass in high-latitude permafrost regions, in global carbon emissions. The decomposition and combustion of organic carbon in permafrost regions due to wildfires release more greenhouse gases into the atmosphere, potentially amplifying the positive feedback between atmospheric greenhouse gas accumulation and climate warming.