This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: An international study led by researchers at the George Washington University indicates clear global evidence that permafrost is thawing across much of the planet. Using 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, the uppermost layer above permafrost that thaws and refreezes each year.
The findings confirm that permafrost degradation accelerated globally between 2000 and 2024. Published in Communications Earth & Environment, the study represents the first global assessment of long-term active layer monitoring data. Dmitry Streletskiy, lead author on the paper and a professor of geography and international affairs at GW, coordinated data collection from researchers and monitoring sites around the world.
The data showed significant increases in active layer thickness across most monitored regions. 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 the 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 affected 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, greenhouse gases known to accelerate climate change. "One of Earth's most important indicators of climate change is permafrost because it reacts directly to rising temperatures," Streletskiy said. "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." 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 collected measurements for more than a decade. The findings build on previous work by Streletskiy and colleagues documenting the growing societal costs of thawing permafrost.
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