Permafrost melt.


Arctic permafrost -- hard, permanently frozen ground -- thaws and collapses as temperatures rise, forming sinkholes that destroy homes, highways and pipelines. In low-lying areas, seawater inundates sinking areas of melted permafrost. In this Landsat image of Cape Halkett, along the north coast of Alaska, green and light blue indicate land lost to permafrost melting between 1955 and 2005. Heat-trapping greenhouse gases held within the permafrost, such as carbon dioxide and methane, are released when it melts, further contributing to atmospheric warming. Methane is 25 times more potent per molecule than carbon dioxide as a greenhouse gas. If the high northern latitudes continue warming at current rates, the region's soils will release more carbon dioxide and methane into the atmosphere, which could accelerate global warming.

Image taken by the Landsat satellite. Credit: Mars/Houseknecht, USGS.
More visualizations from +NASA at http://svs.gsfc.nasa.gov/Gallery/
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