Permafrost soils are permanently frozen soils (for at least two consecutive years) that occur in polar and mountainous regions. However, it is possible for the surface layers of permafrost soils to thaw to a depth of about half a meter during summer.
When permafrost thaws, it impacts the local landscape, infrastructure, economy, and population. The melting of the irregularly distributed ice causes uneven subsidence of the land surface, which can lead to the sinking of roads, railroad tracks, runways, buildings and oil and gas pipelines.
Due to feedback effects, the thawing of permafrost also impacts the global climate and the entire ecosystem, as additional greenhouse gases are released, accelerating global warming.