Natural > Permafrost
Raster > Natural > Permafrost
Data Source: NASA Earth Observations > Permafrost
Website: https://neo.gsfc.nasa.gov/view.php?datasetId=PermafrostNSIDC
Description
In polar latitudes and high elevations, the ground can stay frozen all year. If the ground stays frozen at least two years in a row, it is called "permafrost." Different places have different amounts of permafrost. In any particular place, the permafrost may stretch unbroken across a wide area (continuous), or it may occur in patches (discontinuous). Permafrost can be covered by overburden - a layer of dirt that either doesn't freeze at all, or that thaws in the summer - that is anywhere from a few inches to several feet thick.
The colors on this map show different extents of permafrost in the Northern Hemisphere as a percent of the total ground surface. Permafrost covers the most area and contains the most ice in places near the North Pole. High elevations, such as the Rocky Mountains of North America and the Tibetan Plateau of Asia, also have permafrost even though they are farther south. This map of permafrost is based on a combination of field observations and inferences based on what is known about an area's geology, climate, and vegetation.
Widespread melting of permafrost is one sign of global warming. As permafrost melts, it changes the water cycle, increasing freshwater runoff into the oceans. Lakes and ponds that overlie the frozen ground may "crack" and drain as the permafrost melts. As the ground thaws, microorganisms in the soil become more active, which releases carbon dioxide and methane (greenhouse gases) into the atmosphere. In some places, melting permafrost has caused roads and railways to buckle.
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