Methane-Filled Lake Sets Air Above It Ablaze

Live Science

Thawing permafrost has released so much methane into Esieh Lake near Fairbanks, Alaska that the air above it is flammable.   Credit: Katey Walter Anthony/ University of Alaska Fairbanks

Transcript

00:01We're out standing on a frozen lake in interior Alaska, outside of the University of Alaska

00:06Fairbanks campus, and this ice is already about 20 centimeters thick, so as it's been

00:14freezing up, methane gas has been coming out of the bottom of the lake and getting trapped

00:18in the lake ice.

00:19If you look at the shore, you can see that there are lots of trees that are falling in

00:23the lake and they're dying.

00:24What's happening is the permafrost is thawing, and the ice that was in the ground, when it

00:29melts, causes the ground surface to collapse.

00:31When the forest falls in and any organic matter, dead plant and animal remains that were in

00:38the permafrost, thaw out in the bottom of the lake, microbes decompose it and it generates

00:44methane.

00:45And methane doesn't like to stay in water, in solution.

00:49It forms bubbles, and those bubbles make their way to the surface.

00:52In the summertime, the bubbles pop and they enter the atmosphere.

00:56In the winter, however, this ice forms a cover on the surface of the lake.

01:00And the bubbles get trapped right under the ice, and then the ice thickens and freezes

01:05around them.

01:06So what we have out here is like a time-lapse photograph of methane emissions from the lakes.

01:13Methane is a very potent greenhouse gas.

01:15A molecule of methane is 25 times stronger than carbon dioxide.

01:19Methane is formed in millions of lakes around the Arctic, where permafrost is thawing.

01:28And each year, these lakes are emitting already tremendous amounts of methane.

01:32But when we look at how much carbon is in permafrost still frozen, and the potential for

01:37that permafrost to thaw in the future, we estimate that more than 10 times the amount of methane

01:42that's right now in the atmosphere will come out of these lakes.

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