For millennia, the tundra regions of the Arctic drew in carbon from the atmosphere and locked it in permafrost. That is the case no more, according to an annual report issued on Tuesday by the National Oceanic and Atmospheric Administration.

The Arctic region is no longer a carbon sink. It stores less greenhouse gas than it emits, largely due to increased wildfires. However, emissions from human activities remain the primary driver of climate change.

Wildfires and thawing permafrost are causing the Arctic region to release more carbon dioxide and methane than its plants remove.