Arctic Dispatch: Thermokarst and Toolik

The team studies consequences of the Arctic’s warming temperatures

Marine Biological Laboratory research assistant Rich McHorney
Marine Biological Laboratory research assistant Rich McHorney gets a sample core from the permafrost. Christine Dell’Amore

We know that temperatures have risen in the Arctic, but today we saw evidence of its effects. Known as "thermokarst", these are spots where melting permafrost collapses and forms deformed valleys and pits, allowing water to pool on top of exposed earth. Toolik researchers were surprised when they first spotted these dramatic features from a helicopter in 2003, as thermokarst was unheard of in northern Alaska. In aquatic ecologist Linda Deegan's 25 years working at Toolik, no one had ever seen thermokarst, she told us. "It was something Russians talked about," she said. When a Toolik geology team surveyed thermokarst in the Arctic between 2006 and 2007, they expected to find 100 spots, but instead discovered about 260. Scientists now know of six or 10 around Toolik alone. Thermokarst is a natural Arctic process, of course, but the question arises as to why these events are more frequent and widespread in the Arctic. Is it due to global warming? The jury is still out.

Aside from how many times these so-called soil failures occur, Deegan and others are also looking at the possible effects of thermokarst on stream chemistry. At a thermokarst site near the field station, long green ribbons of water cut through the tundra on their way to the Toolik River. As the water flows over bare dirt, it picks up minerals such as calcium and nutrients such as nitrogen that are contained in the soil. Most Arctic ecosystems are low in calcium -- lakes often lack snails because the animals need calcium to build shells -- so this sudden influx of calcium from thermokarst areas could drastically change the fabric of the stream's ecology. A paper just published by Toolik researcher William Bowden in the Journal of Geophysical Research contended that if thermokarst increases with warming temperatures, there will be "substantial and widespread impacts" on Arctic streams.

We received an introduction to the research that Bowden and others did at the thermokarst site, sampling water and surveying the elevation of the thermokarst. Afterward, Marine Biological Laboratory research assistant Rich McHorney dug out the top layer of tundra to show us the frozen layer of permafrost underneath. I spread my palm on cold, solid permafrost, and almost immediately water began to bubble up and the permafrost began to melt. By the time McHorney hammered a core sample of the permafrost, a small pool had formed on the exposed area. It was a reminder about the fragility of this place, and how even slight changes may have consequences that trickle down to other parts of the ecosystem.

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