Related topics: carbon dioxide · climate change

Investigating the dynamics that reshape permafrost environments

When permafrost thaws, water can flow more quickly through the ground, creating a complex subsurface flow system. Researchers at the Barrow Environmental Observatory in Alaska gained insight into this process by taking daily ...

Scientists find new indicators of Alaska permafrost thawing

More areas of year-round unfrozen ground have begun dotting Interior and Northwest Alaska and will continue to increase in extent due to climate change, according to new research by University of Alaska Fairbanks Geophysical ...

Overgrazing disrupts entire ecosystem

The Tibetan highlands have a special significance both as a grazing ecosystem and global carbon store. Furthermore, it plays a key role in the formation of the monsoon and supplying of potable water for a fifth of the earth's ...

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In geology, permafrost, cryotic soil or permafrost soil is soil at or below the freezing point of water (0 °C or 32 °F) for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of the ground material. Most permafrost is located in high latitudes (i.e. land close to the North and South poles), but alpine permafrost may exist at high altitudes in much lower latitudes. Permafrost accounts for 0.022% of total water and exists in 24% of exposed land in the Northern Hemisphere.

The extent of permafrost can vary as the climate changes. Today, a considerable area of the Arctic is covered by permafrost (including discontinuous permafrost). Overlying permafrost is a thin active layer that seasonally thaws during the summer. Plant life can be supported only within the active layer since growth can occur only in soil that is fully thawed for some part of the year. Thickness of the active layer varies by year and location, but is typically 0.6–4 m (2.0–13 ft) thick. In areas of continuous permafrost and harsh winters the depth of the permafrost can be as much as 1,493 m (4,898 ft) in the northern Lena and Yana River basins in Siberia. Permafrost can also store carbon, both as peat and as methane. The most recent work investigating the permafrost carbon pool size estimates that 1400-1700 Gt of carbon is stored in permafrost soils worldwide. . This large carbon pool represents more carbon than currently exists in all living things and twice as much carbon as exists in the atmosphere.

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