Permafrost is ground that remains frozen for two or more consecutive years, located mainly in the Arctic, Antarctic and high mountains. It consists of soil, rock, sediment and organic matter locked in ice at or below zero degrees Celsius (32 degrees Fahrenheit), and in some regions it can be up to 700,000 years old.
Permafrost directly underlies approximately eleven percent of the earth's total exposed land surface (i.e., land that is not covered by glacial ice). In the northern hemisphere it underlies about 15 percent of the exposed land area, whereas it is much less in the southern hemisphere. It is the foundational force that shapes the Arctic tundra's landscape and biology, while tundra is the entire treeless ecosystem (the biome) that thrives on top of it.
The earth's permafrost has been thawing rapidly due to global warming, resulting in severe environmental problems. One major issue is that its role as a carbon sink has been reversed, and it has now become a net carbon source. Microbes break down the newly exposed organic matter, releasing carbon dioxide and methane (a far more potent greenhouse gas), creating a positive feedback effect that accelerates climate change.
This thawing also disrupts ecosystems by altering drainage, soil stability, and vegetation, threatening Arctic biodiversity. It can damage infrastructure such as roads, pipelines, and buildings in cold regions. In addition, wildfires in thawing areas release vast quantities of carbon dioxide into the atmosphere, in some cases exceeding the annual emissions of entire countries. Furthermore, toxins such as mercury can be released into water, contaminating drinking supplies and food chains, with risks of neurotoxicity and disease.
Climate control policies have increasingly recognized the issue of the thawing of the permafrost, but it is still not fully integrated into global climate strategies. While some interventions, such as wildfire management, peatland restoration, and sustainable caribou herding, can help slow the thawing and reduce emissions, international cooperation remains limited, and progress has been slowed by geopolitical tensions.