Global Study Finds Permafrost Thaw Deepening Across 156 Sites

Is the ground that locks away carbon quietly giving way? A first global assessment of long-term permafrost monitoring covers 156 sites with records from 2000 to 2024, averaging about twenty years each. Active layer thickness, the depth of annual thaw above permafrost, rose significantly at 55 percent of Arctic sites.

Thaw deepened at 38 percent of Antarctic sites and at over 90 percent of mountain permafrost sites. Two Norwegian mountain sites deepened by 8.45 centimetres per year, and Swiss Alpine sites by 9 to 36 centimetres. The Qinghai-Tibet Plateau averaged 3.2 centimetres annually, about four times the Arctic average for continuous permafrost.

Summer warmth is the main driver of Arctic thaw, and wetter summers deepen it further, while thick organic layers buffer the change and wildfire-affected sites show larger increases. About 70 percent of permafrost organic carbon sits in the top three metres, where thawing can release carbon dioxide and methane. The study appears in Communications: Earth and Environment.