The Peril below the ice.  - Scientific American Earth 3.0

Today, nearly seven years after igniting that first bubble, Katey Walters finds herself centre stage in an environmental drama playing out  across the frozen north. Now a 33-year-old assistant professor at her alma mater, the University of Alaska-Fairbanks, Walter was the first to explain the mysterious methane emissions from Arctic Lakes. She isn’t shy about touting their significance as a ticking time bomb. In a complete Arctic thaw, these lakes could discharge a whopping 50 billion tons of methane: 10 times the amount already helping to heat the planet.

Whether a total or more moderate release is in store is still anyone’s guess. But pound for pound, methane in the atmosphere traps 25 times more of the sun’s heat than CO2 does. Consequently, even a modest thaw of the perennially frozen soil that lies under these ephemeral lakes and caps the dry land around them could trigger a vicious cycle: warming releases methane and creates lakes, which thaw permafrost and liberate more gas, which intensifies warming, which creates more lakes, and so on. Some Arctic lakes are growing larger, and researcher’s are eyeing them suspiciously as a reason why global methane concentrations shot up in 2007 and have stayed high ever since. Other signs indicate that permafrost thawing on the Arctic seafloor may be loosening the cap on large pockets of methane stored deeper down.

e mper the escalating threat.

 Kate Walter Biogeochemist, University of Alaska- Fairbanks.

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Walter is sounding the alarm even louder than before because global warming is taking a special toll across the far north. The region is heating up twice as quickly as the rest of the globe, rapidly melting sea ice in the Arctic Ocean as well as the permafrost, which underlies 8.8 million square miles of the Northern Hemisphere. Leading climate models already suggest greenhouse warming as a result of most of the Arctic’s permafrost thawing by 2100 - and the estimates do not yet include the potentially vast additional warming imparted by methane bubbling up out of chilly waters. Walter and others are trying to determine just how much methane could be released into the atmosphere, how soon, how aggressively that release would accelerate the earth’s warming and whether anything can be done to temper the escalating threat.

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The Oregon Graduate Institute has been involved in a project to accurately monitor methane concentrations worldwide for several decades, and the data for the Khalil et al. article come from “weekly flask sampling measurements taken at six strategically located sites, one in each of the polar, middle, and tropical latitudes of both hemispheres (Barrow, Alaska 71.16 N, 156.5 W; Cape Meares, Oregon 45.5 N, 124 W; Mauna Loa 21.08 N, 157.2; Wand Cape Kumukahi 19.3 N, 154.5 W, Hawaii; Samoa 14.1 S, 170.6 W; Cape Grim, Tasmania 42 S, 145 E; and Antarctica including Palmer Station 64.46 S, 64 W and the South Pole 90 S).” They used some statistical wizardry to produce a global average for every month, and the results are presented in the chart above.

Global monthly methane concentration in parts per billion (ppb).