Overview

• The Arctic-boreal region, historically a major carbon sink, is now a net emitter of carbon dioxide across 34% of its area, rising to 40% when wildfire emissions are included.
• Thawing permafrost, which contains vast amounts of stored carbon, is a key driver of this shift, as warming temperatures accelerate decomposition and greenhouse gas release.
• The study, published in *Nature Climate Change*, combines three decades of satellite and field data from over 200 sites, offering the most comprehensive assessment of the region's carbon flux to date.
• While some areas are experiencing increased vegetation growth due to longer growing seasons, this 'greening' is insufficient to offset emissions from thawing soils and wildfires.
• Researchers warn that these changes in the Arctic carbon cycle could significantly impact global climate targets, as permafrost emissions are not always accounted for in national carbon budgets.