For the first time in a decade, scientists reported dramatic increases in levels of methane. More of the potent greenhouse gas has been added to the atmosphere and the Arctic Ocean, suggesting a new imbalance in the Earth’s climate.
 | Methane SinkThe Masej Maszej valley in Altai Siberia. The Siberian tundra traps huge amounts of methane but as permafrost melts the potent greenhouse gas is released (Photo: Shutterstock) |
The amount of methane in Earth's atmosphere shot up by several million tons in 2007, scientists reported the following year, ending a decade of stability. A greenhouse gas 25 times more potent than CO2, methane is responsible for almost a quarter of man-made climate change.
If large stores of methane suddenly escaped, they could trigger runaway climate change. The west Siberian peat bog alone could hold some 70 billion tons of methane.
Methane emissions leak into the atmosphere through the Earth’s crust, wetlands, rice paddies, coalmines, and from decaying or burning organic matter. It is also produced by the gas and coal industries and belching livestock.
The last time methane levels rose significantly was during the El Nino of 1997 and 1998 when emissions from wetland and rice growing regions and biomass burning increased.
But 2007 was not an El Nino year, so scientists focused instead on unusually high temperatures in Siberia, where melting permafrost could have exposed dead plants and animals that then decomposed, releasing methane. Thawing soil also releases methane that is already in gas or ice form.
 | Picture Gallery (click on the picture to start)Discover ten of the most important sources of man-made greenhouses gases (Photo: Reuters) |
Meanwhile, the International Siberian Shelf Study 2008 reported the “highest ever” levels of dissolved methane in the summertime in the Arctic Ocean. Gas, the scientists reported, was bubbling up from the sea floor making seas foam.
The data indicated that the underwater permafrost was thawing, one cause of which could be warmer water coming from Siberia's rivers due to melting permafrost on the land.
Given that the amount of methane stored beneath the Arctic is greater than the total amount of carbon locked up in global coal reserves, there is intense scientific interest in the stability of these deposits as the region warms faster than other places on Earth.
Scientists said it was too soon to tell whether the one-year rise in methane is the start of a trend or an anomaly. They could not yet explain how methane levels rose not just in Siberia but everywhere around the globe. The situation will require vigilant monitoring in 2009.
editor: James Tulloch
publishing date: December 19, 2008
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