Permafrost is ground that stays below freezing for two years or more, capped in summer by a thawing active layer that plants root into. Its freeze and thaw builds periglacial landforms unique to cold climates: patterned ground in polygons and rings, ice-cored pingos, and thermokarst terrain where melting ground ice collapses the surface into lakes and slumps. Permafrost underlies roughly eleven percent of the world's land, and holds an estimated 1,400 to 1,650 billion tons of organic carbon built up over thousands of years. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/
Facts
Process Type TimescaleSeasonal, in the annual freeze-thaw of the active layer, to millennia, in the persistence of the permafrost body itself. 1 First Proposed Year Connections
Associated With
Demonstrated By
Source Permafrost (Wikipedia)
Continuous permafrost underlies most of the Arctic's land area.
Source Permafrost (Wikipedia)
Open Questions
Source Permafrost (Wikipedia)
Sources
1. Permafrost (Wikipedia)
Wikimedia FoundationExtent and landforms sections, description
Permafrost contains organic matter equivalent to 1400-1650 billion tons of pure carbon, which was built up over thousands of years.
Demonstrated By: Siberia, Classification and extent section
Most of this area is found in Siberia, northern Canada, Alaska and Greenland.
View the Source 2. Periglaciation (Wikipedia)
Wikimedia FoundationLead sectionQuote, Lead section
Periglaciation became a distinct subject within the study of geology after Walery Lozinski, a Polish geologist, introduced the term in 1909.
Open Questions (1 open question)
How much carbon will permafrost thaw actually release this century, and how much of it will come from abrupt rather than gradual thaw?
Permafrost holds an estimated 1,400 to 1,650 billion tons of organic carbon. Even under a high-warming scenario, only an estimated 5 to 15 percent of it is expected to be lost over decades and centuries through gradual thaw, but abrupt thaw processes (thermokarst collapse, thaw slumps) release proportionally more methane, accounting for an estimated 40 to 70 percent of the total warming impact from permafrost carbon, and abrupt thaw remains far harder to model and quantify than gradual thaw. Vegetation regrowth is very unlikely to offset the emissions either way. The range between the gradual-thaw and abrupt-thaw estimates is wide enough that the century-scale climate impact is not yet pinned down.
What would resolve this Long-term field monitoring of abrupt-thaw sites across the permafrost zone, paired with permafrost carbon models that fully incorporate abrupt thaw rather than gradual thaw alone.
Climatology and Earth system sciencePermafrost (Wikipedia)
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