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Time On The Shelf
Antarctica (SPX) Jul 13, 2005 Robert Bindschadler stood on a remote stretch of the West Antarctic Ice Sheet and searched the horizon with a growing sense of anxiety. He couldn't see the horizon! While Bindschadler focused on his work�driving flagged poles deep into the ice and carefully recording their precise coordinates�clouds gathered quickly overhead, cloaking the dazzlingly bright blue sky in a shroud of sameness that disoriented him. In a matter of minutes the world around him became a vast featureless white space where he could no longer distinguish sky from surface. With no shadows and no contrasting color shades, humans lose depth perception. Bindschadler had to concentrate just to walk without stumbling. He gathered his gear and trudged back to his snowmobile. He knew it was dangerous to be alone in such conditions so far from base camp. He also knew it was dangerous to attempt driving back to base camp. The ice held hidden hazards that could claim his life in an instant. "When ice moves rapidly, it can experience stresses large enough to crack it," Bindschadler explains. "Some of these cracks, called crevasses, can be quite large and dangerous�30, 50, even 100 feet deep. Some crevasses are covered by thin bridges of snow so they are hard to spot." Such bridges collapse easily under the weight of a person. "Unless one is roped and connected to something or someone else, one usually doesn't survive a fall into a crevasse," Bindschadler says in a tone that conveys self-admonishment. He knew better than to allow himself to get caught in such a predicament. Nevertheless, he faced a difficult decision: hunker down until the weather cleared, or keep going and risk getting lost in the white-out conditions, or worse, falling into a crevasse. In hindsight, Bindschadler admits, he should have stopped and dug himself a snow shelter. "Given that weather conditions can change rapidly in Antarctica, field workers need to always be prepared with the essentials for survival: food, fuel, and shelter," he recites. "If you have a shovel, you can build shelter. If you have food and fuel, you'll be okay." He had a shovel, food, and fuel. Yet there he was astride his snowmobile, in white-out conditions, squinting ahead at the flat expanse of ice for signs of his previous passage. He felt he would be safe retracing his path back to base camp. But it was hard to focus and the surface yielded precious few clues. What would have been a 30-minute trip under clear skies on a beeline back to base camp became a 3-hour meandering ordeal during which Bindschadler constantly second-guessed his decision to keep going. He heaved a sigh of relief when the shadowy silhouette of base camp finally appeared out of the whiteness ahead. Crevasses and rapid, extreme shifts in the weather are just some of the hazards Bindschadler faces in his work as a glaciologist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "A glaciologist is somebody who studies ice," he says flatly. Specifically, his job is to measure the shape of ice sheets. How thick are they? How long are they? Are they growing thicker or thinner? Are they surging forward to cover more area, or retreating to expose more of the underlying land? How fast are they moving? A glaciologist's goal is to be able to measure the "mass balance" of a given ice sheet. That is, how much ice the sheet accumulates from snowfall over the course of a year minus how much it loses due to melt as well as the periodic calving off of large ice chunks. Ice sheets can be good indicators of what the climate is like in a given region; changes in the climate can cause changes in Earth's ice sheets. This simple fact points to the ultimate question facing glaciologists today: As the globe warms will Antarctica's ice mass remain in balance? Or, will the southern continent gain or lose ice mass over time?
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