Two of my friends – ecologists for the National Park Service in Alaska – have a pretty cool job. Every summer their field season rolls around, which means they spend the better part of four months in the glacier-rich wilderness in lieu of hot Fairbanks. But the signs of climate change they consistently see in the parks are not good. Permafrost melts and creates soggy tundra, while elsewhere lakes dry up and water chemistry levels change.
The arctic is important to global warming because the tundra locks up big stores of carbon. A new <a href='article‘ >articlepublished in Nature shows that the wetter the tundra becomes, the more carbon it’s likely to give off. The study took place at a big lake near Barrow on the arctic ocean. They split a lake into three parts. Lake 1 they left the same. From lake 2 they shoveled water into lake 3, making lake 3 extra wet and lake 2 extra dry. With instrument towers, they gathered emissions of CO2 and methane from the individual lakes.
Against researcher’s predictions, the flooded lake gave off the most carbon. They thought it would trap carbon better, since higher water levels drown aerobic – oxygen-consuming – microbes that release carbon while they’re busy decomposing plant matter. It turns out, anaerobic microbes – those that don’t need oxygen – survived underwater and continued to release carbon.
Plus, a positive feedback loop was created as permafrost under the flooded lake melted faster than permafrost underlying the crispier lake. The deeper the thaw, the more that old carbon (up to 1,000 years old) is released.
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