How much methane is located in the Arctic?

Arctic sources of carbon have been studied by a team of researchers at Lawrence Livermore National Laboratory, Livermore, California, United States, led by Joshuah Stolaroff. Their estimates are illustrated in the image below, showing the potential total release, next to their characteristic annual release of methane and the geographic extent for each source.
Stolaroff et al., 2012, DOI: 10.1021/es204686w 
Note: Numbers in brackets behind the figures in above table relate to references below. If you cannot view these references, click here. 


For comparison, the NOAA image below shows the world's carbon dioxide emissions for each year in PgC (i.e. GtC or billions of tonnes of carbon).

Annual total emissions. The bars in this figure represent carbon dioxide emissions for each year in PgC yr-1 from the specified region. The final bar, labeled 'Mean', represents the 2001-2010 average. CarbonTracker models four types of surface-to-amosphere exchange of CO2, each of which is shown in a different color: fossil fuel emissions (tan), terrestrial biosphere flux excluding fires (green), direct emissions from fires (red), and air-sea gas exchange (blue). Negative emissions indicate that the flux removes CO2 from the atmosphere, and such sinks have bars that extend below zero. The net surface exchange, computed as the sum of these four components, is shown as a thick black line. 

Clearly, if merely a fraction of the sources at the top would end up in the atmosphere, we'd be in big trouble. Some of the carbon may be released gradually in the form of carbon dioxide, but it's much worse if large amounts of methane escape abruptly into the atmosphere, given factors such as methane's high Global Warming Potential. Anyway, it should be clear that the huge size of some of these sources poses a terrifying threat.  




References
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