Permafrost

An aerial view of the Arctic tundra with permafrost polyons and a pingo.
The Arctic tundra is underlain by permafrost. It forms these polygonal patterns as it thaws and freezes. Also in this picture is a pingo, a large ice core under the surface, another feature of permafrost landscapes.

Permafrost underlies most of the Arctic Network and affects nearly everything in Arctic ecosystems, from soils and vegetation to water and wildlife. Permafrost is frozen ground that doesn’t thaw in the summer due to a cold climate. Permafrost perches water near the surface, making soils wet and runoff fast. The striking polygonal patterned ground so characteristic of the Arctic is due to permafrost. Ice can build up in the ground and then thaw, producing pits, ponds, lakes, and landslides. As our climate warms, permafrost is thawing. Thawing permafrost has many consequences, such as drainage of lakes, creation of new ponds, soil erosion, slumps, siltation of streams and lakes, release of greenhouse gases, and changes in soil wetness and nutrient supplies.
We monitor permafrost across the Arctic Network to document:

  • Trends over time in ground temperatures at representative sites in the Arctic Network. This will indicate whether the permafrost is stable or likely to thaw.
  • The area covered by slumps and landslides due to thaw of permafrost and changes over time.
  • The growth rate of large slumps caused by thaw of permafrost and the rate of sediment loss from slumps.

Contact: David Swanson

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Ice wedges can resemble a giant quilt when seen from the air and form only where permafrost is found. During very cold weather, solidly frozen ground can shrink and crack. When snow melts in spring, water runs into the cracks and freezes, which causes the cracks to grow. Most cracks are preserved beneath the ground surface. If the ground above ice wedges is disturbed by vehicle traffic or warmer conditions, however, the ground above the cracks melts and reveals the ice wedges.

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    Last updated: August 23, 2020