Submitted by Anonymous on Wed, 04/03/2013 - 09:21
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Carbon Balance in Warming and Drying Tundra 2013

Hello Team AK! Exciting stuff. How thick is the permafrost? How does 'depth' of permafrost thickness correlate with ice age? What limits permafrost depth? What sort of organic and inorganic material is in the permafrost? Is it like glacier ice, at all (with pressure from something above it?) What are frost heaves?

Mon, 04/08/2013 - 22:32

Tom Lane

Thanks for the great questions. I can answer a few now, a couple however I need to get in touch with Ted Schuur (an expert on permafrost and PI of this experiment).Permafrost is simply ground that stays frozen year around. This is generally frozen subsurface soils, rocks, vegetative and other organic matter that can be several feet to more than a thousand feet in thickness. It's depth is only limited by temperature. Some permafrost may be limited in depth by radioactivity, volcanism and other heat found subsurface. Frost heaves are when water percolates through cracks the subsurface soil, freezes, expands and buckles the overlaying surface. This water melts and then the surface either sinks or can remain buckled. Okay, so...I was able to speak with Ted who happens to be here at the field cabin this week during "shovel" week. To be clear, permafrost relates to temperature. If it is behaving like glacial ice (which it could technically on a steep slope response to gravity, called "para-glacial slopes") then it is something else. The permafrost at CiPEHR is hundreds of feet deep. There is a bore hole on the Gradient research site that is 30 meters and the bottom is still in permafrost. Permafrost may correlate with ice age in that there is permafrost here that was created during the Holocene as well as permafrost that was created during the Pleistocene.