Features formed by melting permafrost provide clues to a changing Arctic landscape and climate
By Lisa Jarvis There is a profound quietude north of Alaska’s Brooks Range, the string of mountains separating the boreal forest from the Arctic tundra. Traveling along the Dalton Highway, the one road to the Arctic Ocean, one sees little visible movement in the landscape aside from the trucks barreling up to the oil fields, an occasional camper, or subtle signs of wildlife. Every angle, every turn offers stillness and beauty; it is like driving straight into a postcard. Yet the tranquility belies the dramatic change under way. The climate in the Arctic is warming more rapidly than nearly anywhere else. Sea ice is disappearing faster than models had predicted—everyone has seen the images of a polar bear stranded on a shrinking ice floe—and the frozen soil is warming as far as 65 feet below Earth’s surface, points out Syndonia Bret-Harte, a plant community and ecosystem ecologist at the University of Alaska’s Institute of Arctic Biology. No one is more keenly aware of how quickly the environment is changing than the scientists at Toolik Field Station, the National Science Foundation’s Arctic long-term ecological research site, where Bret-Harte is the associate scientific director. Since the camp was established in the 1970s, researchers have returned summer after summer to conduct long-term studies of the plants, lakes, rivers, and wildlife. They see firsthand that in the carefully balanced environment of Alaska’s North Slope, small changes can have major consequences. Now, a large group of scientists are collaborating to understand how the consequences of a warmer Arctic could impact its landscape and feed back into global warming. With a grant from NSF, they are studying the mechanics of thermokarsts, or features created when permafrost, or soil that has been frozen for years, melts, then collapses like a soufflé. Each scientist brings a different kind of expertise that can help create a complete picture of how a thermokarst changes the surrounding environment. “The Arctic is a place where everything is about the minutest change in energy balance,” says William (Breck) Bowden, an aquatic ecologist at the University of Vermont, who has been coming to Toolik for more than 20 years. Just how delicate is that balance? Consider a set of tire tracks visible in the tundra near a pump station off the Dalton Highway on Alaska’s North Slope. The tracks look freshly made, but are actually a relic from the 1940s, when a single vehicle passed over the surface of the tundra. All it takes is the weight and friction of the truck to expose the soil, making a small change to the albedo, or the amount of light being reflected away from the ground’s surface, and the area begins to melt. “And as it continues to melt, a new community of vegetation starts to grow there, and now we have a scar,” Bowden says. …
Trouble In The Tundra
