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(Cheryl Carlin)

Arctic Dispatch: Looking at the Lakes

Alaska’s Arctic lakes are a source of methane experiments for a warming planet

After days of tackling the tundra, I was relieved to visit the lab and see how science happens behind the scenes with Dendy Lofton, a University of North Carolina, Chapel Hill researcher who studies how methane is produced in Alaska's Arctic lakes. She showed me what she calls her "rainbow experiment": a collection of vibrantly colored bottles filled with sediments from various depths of a lake near Toolik. After the bottles have incubated in a specialized water chamber at 10 degrees Celsius for a few days, she analyzes how much methane each sediment sample produces. This will tell her more about how methanogenesis—the formation of methane by the bacteria that eat them—occurs in different lakes. These hardy little critters, called methanogens, produce methane. Another group of bacteria consume the methane and turn it into carbon dioxide.

After Dendy gave me the rundown, she offered up an answer to that ubiquitous question: Why should we care? "Because [methane] is a major greenhouse gas, it's second in importance only to CO2, and atmospheric concentrations [of methane] have increased over last 30, 50 years," she told me. What's more, some of highest concentrations of methane in the atmosphere have been observed in the polar regions, "so there's a reason to study where it's coming from," she says.

In some lakes in the Arctic, methane tends to get pumped into the atmosphere after a lake "turnover," when a natural force—such as barometric pressure—causes lake waters to mix. When that happens, methane accumulated at the bottom of the lake rushes to the top, moving so fast that the bacteria don't have a chance to gobble it up. However, most lakes across the Arctic do not store methane at the bottom.

Scientists have recently started to focus more on how changes in the land can influence methane production in lakes. For instance, as climate change progresses, some scientists are concerned that more organic matter could enter lakes and produce more methane. So Lofton's research echoes the same theme of most Toolik experiments: Anticipating what will happen in a warmer planet.

I missed out on a chance to go with Lofton on a lake sampling this morning because of our last group hike to the aufeis, the same spot we'd visited last week. This time we scrambled up the heath-covered mountain behind the ice, where we got an impressive birds-eye view of the bluish-white formation. Except for the shrill cry of a hawk, the wildlife had apparently decamped to drier ground, so we decided to call it a day early.

Our last night at Toolik was lively: a "rogue" night at the sauna (the sauna's usually closed on Thursdays), and a hilarious boat-inflation contest, where competitors vied to inflate a boat the fastest with various methods—hand pumps, foot pumps, syringes, even breathing. (One of the hand-pumpers won). With a torrential rain now beating down on Toolik, we may be able to use those boats around camp tomorrow morning.

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