Global warming is radically changing the land at the northernmost latitudes. The ground there used to be permafrost, perennially frozen. Due to increasing temperatures, however, it is thawing. This is releasing trapped greenhouse gases into the atmosphere and making climate change worse. Now, a new worrying feature has been identified: An Alaskan body of water called Esieh Lake is bubbling due to methane emissions.
In a feature piece for the Washington Post, writer Chris Mooney talked to Katey Walter Anthony, an associate professor at the University of Alaska Fairbanks. Walter Anthony has been studying the peculiar Esieh Lake and was able to assess the origin of the methane bubbles.
The gases in the lake don’t come from any lifeforms, but they are geological in origin. According to the researchers, there are fossil fuels buried not that far from the bottom, and combined with the thawing of the permafrost, they represent a source of greenhouse gases.
Permafrost covers 24 percent of the land in the Northern Hemisphere and it stores an impressive amount of carbon and methane. It is also important for the structural stability of regions. Meltwater from some permafrost has been shown to contain sulfuric acid. Erosion, landslides, and the disappearance of lakes are likely consequences of large swathes of permafrost melting.
And it is in the connection between the thawing soils and lakes that Professor Walter Anthony focuses her work. In a recent paper, published in Nature Communications, she shows that most models haven’t taken into account the release of deeper pockets of greenhouse gases, especially in lakes. This thawing could also be abrupt and not as gradual as the thawing permafrost releases have been modeled so far. The episodes could more than double the carbon release from permafrost.
The lake emits about two tons of methane gas every day (around 6,000 cows). It is but a drop in methane emissions from thawing permafrost, but as always we need to consider the bigger picture. Esieh Lake might be a peculiar geological feature – a one-off and nothing more – or it could be an example of a wider trend of lakes in the North of the world.
Given the extent of permafrost, it will be difficult to study every single body of water forming in previously frozen terrains. However, it's important that worst-case scenarios are seriously studied rather than summarily dismissed. And this lake could be just that.
[H/T: Washington Post]