What lies beneath

"I'm all out of ideas," says hydrologist Mike Gooseff, still smiling despite his frustration.On a crisp, unusually warm and dry August afternoon on Alaska's North Slope, a few miles from the Toolik Lake Long-Term Ecological Research (LTER) field station, a two-meter metal rod is wedged in pristine streambed, irretrievable despite nearly an hour of yanking, pushing, prodding, and countless Rube-Goldberg-like brainstorms. Someone had forgotten to slip on a metal piece that would give a jack enough

Sep 13, 2004
Eugene Russo

"I'm all out of ideas," says hydrologist Mike Gooseff, still smiling despite his frustration.

On a crisp, unusually warm and dry August afternoon on Alaska's North Slope, a few miles from the Toolik Lake Long-Term Ecological Research (LTER) field station, a two-meter metal rod is wedged in pristine streambed, irretrievable despite nearly an hour of yanking, pushing, prodding, and countless Rube-Goldberg-like brainstorms. Someone had forgotten to slip on a metal piece that would give a jack enough leverage to dislodge the rod, part of a long-term study monitoring the effects of Arctic warming, after it had been hammered into the streambed to measure the depth to permafrost. Excalibur simply wouldn't budge.

Definitively answering whether global climate change is indeed occurring – and how precisely that change might reverberate through ecosystems – is complex business. The experiments that push the envelope, seek some small clues, and fuel the science, however, are often performed using rather simple, blunt instruments, such as rods jammed into a riverbed.

Gooseff, an assistant professor at Utah State University, and his group leader, Breck Bowden, a professor of watershed science and planning at the University of Vermont most of the year, spend the summer using red dye to measure stream-water patterns, and pulling rafts across streams to measure depth to permafrost via radar. The multiyear study has just started.

Permafrost is the icy subsurface that binds most studies here. A year ago, on a clear day as Bowden flew over the tundra in a helicopter used to transport heavy equipment to hard-to-reach tundra spots, he noticed unusually dark sediment pouring into the water below. He followed the river upstream and discovered the source of the muddiness: a thermokarst, the caving in of the permafrost and tundra above due to warming.

The collapse had formed a cavern that continued to widen, exposing roots that haven't seen the light of day for thousands of years. The sediment released could have far-reaching implications for the river ecosystem for years to come, says Bowden, because vegetation and fish may have trouble adjusting to their new murky habitats. Four thermokarsts have now been found in the area in the last two years, a higher rate than usual, and more could remain hidden. Are thermokarsts the sort of "canary in the coal mine" that climate change researchers look for? It's hard to say; no long-term records are available, and systematically surveying large swathes of Arctic lands would be a mammoth undertaking.

Indeed, the whole of Alaska could be a canary in a coal mine because of its climate. In the last 30 years, temperatures in Alaska have risen an average of just under -16.3°C statewide based on data from 18 weather stations. Increases are especially pronounced in the spring, and the winter work season, the time during which the tundra is frozen enough to conduct seismic oil exploration, has shrunk considerably from 218 days in 1970 to 103 in 2002. Meanwhile, other areas of the world have had less pronounced effects. Indeed, some parts of Canada have cooled over the last few decades.

Toolik researchers do not place the blame on global warming, explains Bowden. Rather, they hope to target one part of one complex ecosystem to begin to piece together a comprehensive picture, an account that even then will likely be open to interpretation by policymakers.

Warming permafrost, some investigators reason, might trigger the release of nutrient quantities to which plants and animals aren't typically exposed. Donie Bret-Harte, associate director of the Toolik field station, has for years added small quantities of fertilizer to the dwarf birch, Betula nana, including phosphorus in particular, which is normally only available to tundra plants in short supply. After a few years, they flourish, growing to many times their normal size.

Postdoc Jon Benstead and his group measure and weigh fish, attempting to glean any effects from a phosphorus drip upstream. The results are, well, complicated. Thus far it's been hard to separate temperature effects from fertilizer effects. The adults appear to thrive under cold, high-water conditions, whereas the young prefer dry, low-water conditions. But there does seem to be a bit more overall growth among the fertilized, according to Benstead.

Bowden says that Toolik scientists have gotten better at keeping their eyes on the "big-picture" questions. Experiments have evolved from individual undertakings to sophisticated, integrated, multidisciplinary, multi-institutional studies. Researchers are still trying to find the right combination of experimental tools to handle the complexities.

Today, those tools should've included a simple piece of metal. Gooseff returns to camp shaking his head. "We're never going to hear the end of this one," he says, still smiling. They return to the site with a wrench in hand. Within five minutes they'd twisted the rod, dislodged it, and pulled mighty Excalibur from the streambed.

- Eugene Russo