The International Permafrost Association (IPA) is an integrator of issues regarding permafrost. Subarctic climates are cold with continuous permafrost and little precipitation. It was judged that increased emissions of carbon from thawing of permafrost could occur. Regions of permafrost cover much of the Arctic. Much of the Canadian Arctic is covered by ice and permafrost. Estimates vary on how many tons of greenhouse gases are emitted from thawed permafrost soils. These cold climate landforms appear in regions of permafrost and seasonally frozen ground. Permafrost and tundra cover most of the region. "Thermal erosion" is the result of melting and weakening permafrost due to moving water. The permafrost/glacier line generally starts around . They form where sunwarmed water has melted basins in the underlying permafrost. Adfreeze pile foundations are particularly sensitive in conditions which cause the permafrost to melt. This includes sea ice, ice sheets, permafrost and snow cover. Permanently frozen ground is known as permafrost. The presence of ground permafrost is important to the persistence of some lakes.