Global Study Indicates Widespread Permafrost Degradation

An international study led by researchers at the George Washington University Department of Geography and Environment demonstrates clear global evidence that permafrost is thawing across much of the planet.

Utilizing more than two decades of field observations from 156 monitoring sites across the Arctic, Antarctic and high-mountain regions, the study found increases in the thickness of the active layer, which is the uppermost layer above permafrost that thaws and refreezes each year. The results confirm that permafrost degradation has accelerated globally between 2000 and 2024.

"One of Earth's most important indicators of climate change is permafrost as it directly reacts to rising temperatures," said Dmitry Streletskiy, a professor of geography at the Columbian College of Arts and Sciences (CCAS) and lead author on the paper. "The significance of this study lies in the fact that we're not just looking at isolated hotspots anymore. The collaborative efforts of the involved sites show a pattern that spans continents and climate zones, telling us that global permafrost degradation is already well underway."

Published in "Nature Communications Earth & Environment," the study represents the first global assessment of long-term active layer monitoring data. Streletskiy coordinated the data collection from researchers and monitoring sites around the world. The team found significant increases in active layer thickness across the majority of monitored regions.

Among the CCAS co-authors of the study, titled "Long-term Monitoring of Active Layer Thickness Confirms Global Permafrost Degradation," are Assistant Research Professor Kelsey Nyland; Professor of Geography Nikolay Shiklomanov; Graduate Research Assistant Emma Haggerty, B.S. '24, M.S. '26, Cert. '26; and Associate Professor of Geography Michael Mann.

Thawing threats

Permafrost is ground made up of soil, rock and sediment bound together by ice that remains frozen for at least two consecutive years. It underlies nearly 15% of land surface in the Northern Hemisphere and nearly all ice-free land in Antarctica. As the active layer becomes thicker over time, it signals that the ice deeper in the ground is thawing.

Thawing permafrost threatens infrastructure built on frozen ground, including roads, railways, airports, pipelines, buildings and utility systems, causing economic and safety challenges for impacted communities. In addition, scientists estimate that the top three meters of permafrost contain around 70% of the organic carbon stored in permafrost soils. As the ground thaws, that carbon is released into the atmosphere as carbon dioxide and methane, which are greenhouse gases known to accelerate climate change.

The research synthesized observations collected through the Circumpolar Active Layer Monitoring (CALM) program, a network of sites established in the 1990s to observe the long-term response of permafrost to climatic changes and variations in both hemispheres, as well as partner monitoring networks. The data were collected from sites across North America, Europe, Asia, South America and Antarctica, many of which have been collecting measurements for more than a decade.

Key findings of the study include:

• Permafrost degradation is widespread. Active layer thickness increased significantly at 55% of Arctic sites and 38% of Antarctic sites, while increases were observed at more than 90% of monitored mountain sites in Europe and high-elevation regions of Asia, as well as at monitored sites in South America.
  
• Mountain regions experienced the fastest changes. Several high-elevation sites saw the active layer double in thickness, making mountainous permafrost regions among the most rapidly changing environments.
  
• Arctic warming and increasing rainfall are driving change. Statistical analyses found that rising temperatures were the primary driver of active layer thickening in the Arctic. Increasing precipitation, particularly rainfall, served as another important contributor.
  
• More monitoring is needed worldwide. While the Arctic has the longest and most extensive monitoring record, researchers say expanding long-term observations in Antarctica and mountain regions will improve scientists' ability to understand regional drivers of permafrost change.

The findings build on previous work by Streletskiy and colleagues documenting the growing societal costs of thawing permafrost. Earlier studies found that degradation of frozen ground and its impact on transportation systems, buildings, energy infrastructure and other critical assets throughout cold regions could put as much as 50% of Arctic infrastructure at high risk of damage by 2050, costing countries tens of billions of dollars. As temperatures continue to rise, those impacts will become more widespread and costly.