Permafrost Study: "Material That Has Not Thawed Since Deposted By Glaciers Now Beginning To Thaw"

[hatrack]

EDIT

Overlying permafrost is a thin "active layer" that thaws every summer, and increases in the thickness of this layer over the years indicate thawing of permafrost. Both physical measurements and modeling suggest that active layer thickness has increased in some areas over the 20th century and that if present warming trends continue, increases of up to 40 percent could occur by the end of the 21st century.

Although the full effects of thawing are yet to be determined, coastal erosion and damage to the roads, buildings and pipelines that have been built on permafrost are likely outcomes. In addition, thawing permafrost may release the greenhouse gases carbon dioxide and methane into the atmosphere, triggering further warming and more permafrost thawing.

Currently, the main method for determining thaw depth is with a graduated steel probe. "You stick it in the ground and see when it hits frozen material," said geochemist Joel Blum, who with ecologist George Kling and former graduate student Katy Keller undertook the new study. "We were studying the chemistry of soils in the area around Toolik Field Station in northern Alaska, and we found that once we got below the thickness that typically would thaw during summer, the soil chemistry changed dramatically," said Blum, who is the John D. MacArthur Professor of Geological Sciences.

"Material that has not thawed since it was deposited by glaciers 10,000 to 20,000 years ago is now beginning to thaw, and when it does, it reacts strongly with water, which it's encountering for the first time. This soil is much more reactive than soils higher up that interact with soil water every summer." In particular, the amount of calcium, relative to sodium and barium, is higher in the newly-thawed permafrost, and the ratio of the strontium isotope 87Sr to its counterpart 86Sr is lower. The researchers wondered if these chemical signatures of increasing thaw depth could be seen in local stream water.

EDIT

http://www.terradaily.com/reports/Stream_Water_Study_Detects_Thawing_Permafrost_999.html

[JohnWxy]

1. This is why we can't wait 20 years for more GHG reductions. We should aggressively pursue those

methods available to us now, that can (and do) reduce GHG emissions now and can reduce more with increased commitment to them.

recommmended.

[phantom power]

2. k+r

[The Croquist]

3. Sea level has risen 400 feet since the peak of the last ice age

Some how all the carbon dioxide and methane released when those glaciers melted didn't result in runaway climate change.