Polar Meltdown
Is the heat wave on the Antarctic Peninsula a harbinger of global climate change?
During a penguin-counting survey on Cormorant Island, Patterson points to a tiny remnant Adelie outpost. It has two nests, surrounded by a penumbra of smoothed pebbles where hundreds of penguins raised their young 10 years ago. And standing about insolently are half a dozen brown skuas, waiting for a chance to grab a lightly defended baby penguin. Maps of Adelie colonies consistently show that most of the failed colonies are located where snows have become deepest. The chicks born in these places are hatched later and are smaller. Chicks from colonies on northern-facing shores weigh an average of nearly 7 pounds; those on snowier south shores are a pound lighter. "Lightweight chicks won't survive their first winter," Fraser says.
Every failed penguin colony could be just one more local chapter in the pitiless pageant of nature. Certainly, there are no endangered species here. Adelies are flourishing at the southern end of their range in the Ross Sea. And that fits the climate-change model, too. The Ross Sea historically has been so bitterly cold that a little warming there makes it more, not less, hospitable to the Adelies. "Their whole range," Fraser observes, "seems to be shifting south."
But in most of the world, the natural ranges of species cannot move as easily as they can in this vast, unspoiled continent. If warmer weather drives a species to the edge of a city, or to the top of a mountain, that may be the end of it. And that's why the lessons from the Adelies here should demand attention elsewhere.
Palmer is one of several sites in the Long-Term Ecological Research program, sponsored by NSF to keep track of how wildlife in specific areas is doing. While Fraser has been there longest, other Palmer-based scientists track the richness of the bottom of the food chain, including marine algae and other plankton in the sea, the krill that feed on plankton, and microbes living in the water, ice, and thin soil.
Man with a plan. Temperature and snowfall are not the only changing environmental factors here, either. The famed ozone hole, a loss of ultraviolet-absorbing ozone molecules in the stratosphere over Antarctica, affects the Palmer area in October and November each year. Ultraviolet radiation levels soar. University of Texas graduate student Jarah Meador found so many bacteria living in the glacier fragments floating in the harbor that she E-mailed Wade Jeffrey of the University of West Florida, principal investigator on a program to monitor the effects of ultraviolet radiation on Antarctic microbes. He had a plan.
One sunny day, after some training in rappelling down ice cliffs with the base search-and-rescue team, Meador hiked up the glacier behind the base and lowered herself on a rope down a narrow crevasse that extended 100 feet into the ice. "It's great down there," she exulted on the way back out. In the deep blue light filtering through the ice, she dug into the vertical wall of ice at intervals, carefully preventing contamination while she gathered samples. If the microbes at great depth turn out to be different from those near the surface, it could mean that evolution is already retuning the microbes to tolerate increased levels of ultraviolet radiation.
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