Permafrost

shellystetson_Small.jpg Anytime you return to a place you lived many years before, you will likely be surprised by changes. You probably would not expect, however, to find the very shape of the land changed. For Global Warming 101 Expedition Team member Theo Ikummaq, however, this is just what happened when he arrived in his former home of Qikiqtarjuaq.

Theo lived in Qikitarjuaq in the 1980s. At that time the Distant Early Warning (DEW Line) station was not visible from town, the rise of the land blocked it from view. The DEW Line station can now be seen from town. The only explanation the local people can find is that the permafrost must have collapsed and let the land settle.

Permafrost is ground that remains frozen even in the summer. All of Baffin Island is permafrost. In the summer only the top of the permafrost, the active layer, thaws.

As the climate warms, the permafrost thaws to greater and greater depths. Across the Arctic melting permafrost is changing the structure of the ground. This destabilizes roads, buildings, pipelines, airports and other facilities. Sink holes form, trees topple, ponds and wetlands disappear, riverbanks collapse, and coastlines erode.

tundra_Lg.jpg The impacts of melting permafrost extend beyond the Arctic. The Arctic permafrost holds large amounts of carbon, the basic building block of life. This carbon accumulated over thousands of years as living things died but, due to cold temperatures, did not decompose. As the permafrost melts, microscopic organisms decompose the carbon, releasing methane and carbon dioxide, both heat-trapping (greenhouse) gasses.

As the permafrost melts and releases its carbon to the atmosphere, that carbon intensifies global warming, which causes more melting of permafrost—a positive (self-reinforcing) feedback loop. There is enough carbon trapped in the Arctic permafrost that, if it were all to be released, it would dwarf human-caused emissions.

Melting permafrost is one of several potential feedback loops through which Arctic warming could have worldwide impacts. To learn about the other feedback loops, check out the Global Warming 101 lesson plans.

Elizabeth Andre

(Source: ACIA, 2004)

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