Methane Bubbles Make Global Warming Worse

Methane bubbles trapped in lake ice in October. (Image credit: Katey Walter.)

Methane gas bubbles up from Siberian lakes at up to six times the rate previously thought as a result of global warming, a new study suggests. The result: more global warming.

One consequence: Carbon in the permafrost is released into the atmosphere. Another is that thawing permafrost along the margins of a lake dislodges frozen plant and animal remains, causing them to sink to the bottom of the lakes, where they decompose and produce methane, a potent greenhouse gas.

Some of the methane diffuses through the lake water and into the air, but the majority of it escapes by bubbling to the surface. Until now, this bubbling, or "ebullition," process has been hard to measure because of the difficulty involved in determining where and when the bubbles will occur.

In the new study, researchers used a combination of aerial surveys, remote sensors and year-round measurements of places in two Siberian lakes where methane bubbling was known to occur. To identify bubble hot spots, they surveyed the lakes in autumn, when bubbles rising to the surface freeze in place, leaving behind visible trails.

The cycle works like this: Thawing permafrost dumps tons of previously frozen organic material into lake bottoms, producing methane. The methane finds its way into the atmosphere, where it works with other greenhouse gases to trap the sun's rays. The planet warms even more, causing permafrost to thaw at a quicker pace.

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