Global warming may melt the top ten feet of permafrost, the frozen soil that stretches across the Northern Hemisphere, from Alaska to Canada to Russia. Fairbanks, one of the largest cities in Alaska, is actually built on permafrost, so this is especially worrying to residents of Alaska.
New computer simulations from the National Center for Atmospheric Research (NCAR) show that over half of the area covered by this topmost layer of ice could thaw by 2050 and as much as 90% could thaw by 2100. This thawing will increase runoff to the Arctic Ocean and release vast amounts of carbon into the atmosphere. It will also cause ocean levels to rise worldwide, affecting coastal cities and island nations.
About one-fourth of the Northern Hemisphere’s land contains permafrost, which is soil that remains below 32 degrees F for at least two years. Permafrost has a surface layer which thaws during the summer and re-freezes during the winter. The deeper permafrost layer underneath remains frozen.
The top layer is effected by global warming, while the deeper permafrost layer has not thawed in climate, expanding downward as surface air rise. Deeper permafrost has not thawed since the last ice age, over 10,000 years ago. It will probably remain unaffected by global warming.
Recent warming has thawed large sections of permafrost in central Alaska, causing soil to collapse as the ice within it melts. The results include buckled highways, destabilized houses, and forests filled with trees learning at wild angles.
Art credit: http://www.freeimages.co.uk
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