A third of the Arctic’s tundra, forests, and wetlands are now carbon emission sources due to global warming, disrupting centuries-old carbon storage in permafrost. A new study published in Nature Climate Change reveals that over 30% of the region emits CO2, increasing to 40% with wildfires. Monitoring data from 200 sites between 1990 and 2020 shows rising temperatures have transformed Arctic ecosystems from carbon sinks to carbon sources. Though Arctic areas are greener, thawing permafrost and active microbial processes contribute to significant carbon release, stressing Earth's natural carbon sinks. The study underscores the importance of improved monitoring amid changing Arctic carbon cycles.