Permafrost

1. Permafrost

2. Definition of Permafrost Permafrost, or permanently frozen ground, is soil, sediment, or rock that remains at or below 0°C for at least two years. It occurs both on land and beneath offshore Arctic continental shelves, and its thickness ranges from less than 1 meter to greater than 1,000 meters.

3. Scientists classify permafrost into two main types: Continuous permafrost Continuous permafrost exists under almost the entire land surface in an area. Areas with continuous permafrost often have permafrost layers more than 100 meters (330 feet) thick. The deepest permafrost ever found is in Siberia, a region in northern Russia. One area in Siberia has a permafrost layer that extends down 1,650 meters (5,413 feet). Discontinuous permafrost Discontinuous permafrost exists under a large portion of a particular area or only in a few specific places. In areas with discontinuous permafrost, the permafrost layer may extend as deep as ten meters (thirty-three feet) underground. Discontinuous permafrost can be isolated or sporadic.

4. Why is Permafrost is Important? Permafrost degradation can substantially change the surface hydrology in many ways. The ground can become over-saturated, which could cause trees to die (Osterkamp et al., 2000; Jorgenson et al., 2001). Permafrost degradation on well-drained portions of slopes and highlands will proceed in a form of "dry thermokarst". This process will further improve the drainage conditions and lead to a decrease in the ground water content (Hinzman et al., 2003). Changes in the active layer thickness and permafrost continuity will affect ground water and river runoffs.

5. Permafrost is Important in regard to Human Structures as Well Thaw settlement related to permafrost degradation is presently responsible for damage to houses, roads, airports, military installations, pipelines, and other facilities founded on ice-rich permafrost (Osterkamp et al., 1997). Any natural increase in the mean annual surface temperature of permafrost and subsequent thaw settlement would create severe maintenance problems for facilities in the Arctic and Sub-Arctic, adding to effects already being observed. Some structures, airports, and roads might have to be abandoned if funds are not adequate to continue repairs (Esch and Osterkamp, 1990). http://www.arctic.noaa.gov/essay_romanovsky.html

24. The discovery of human bodies in melting permafrost, some with diseases that can survive frozen for many years. • Small Pox: Climate Threat: Thawing Tundra Releases Infected Corpses: http://www.livescience.com/2403-climate-threat-thawing-tundra-releases-infected-corpses.html • 1918 Flu: Alaska Science Forum, April 29, 1998, Permafrost Preserves Clues to Deadly 1918 Flu: http://www2.gi.alaska.edu/ScienceForum/ASF13/1386.html

25. Sources and References • http://nsidc.org/cryosphere/sotc/permafrost.html • http://nsidc.org/cryosphere/frozenground/how_fg_forms.html • National Geographic Magazine, December, 2007 - images by Bernard Edmaler, used for educational purposes only, Fair Use Act • http://ngm.nationalgeographic.com/2007/12/permafrost/barry-lopez-text.html • http://ngm.nationalgeographic.com/2007/12/permafrost/edmaler-photography.html • http://www.arctic.noaa.gov/essay_romanovsky.html • http://www.arctic.noaa.gov/permafrost-photos/web/hole-man-shovel.jpg • http://www.arctic.noaa.gov/permafrost-photos/web/stream.jpg • http://www.arctic.noaa.gov/permafrost-photos/web/impact.jpg • http://www.livescience.com/2403-climate-threat-thawing-tundra-releases-infected-corpses.html • http://www2.gi.alaska.edu/ScienceForum/ASF13/1386.html