Author: By Joshua Brown
Here, about 500 miles inland from the coast of Antarctica, UVM geologist Tom Neumann looks out the window of a 12-foot-long box on skis being pulled by a tractor and describes what he sees.
It's early evening, and the box casts a shadow across the vehicle tracks. Beyond, whiteness without relief stretches in all directions, like frozen mist under a blue dome of sky. A north wind rag-whips Norwegian and American flags on the top of another tractor nearby. Probably, no person has ever been to this spot before, he says, speaking to me in Vermont by satellite phone. Outside, it's 25 below and plunging. Inside, it's 70 above and the team of scientists he is traveling with are watching a surfing movie.
Antarctica is layered with contradictions. One of the driest places in the world, it holds more than 60 percent of the planet's freshwater in its vast ice sheet. The coldest place in the world, it may shape the consequences of global warming more than any other land mass.
But what these consequences will be remains murky, despite a spate of recent scientific studies. It could be that warmer air, carrying more moisture, will deposit increasing amounts of snow over Antarctica, building up the ice sheet faster than it melts at the coast. Or, it could be that a warming ocean will increase rates of melt and glacial discharge along the coast faster than the interior grows.
Big Ifs And on this question of "mass balance," as the scientists call it, balances the fate of the world's coastlines. Last year, the Intergovernmental Panel on Climate Change predicted that sea levels will rise in this century by between eight inches and two feet. But if recent findings about the destabilization of the ice sheet in West Antarctica are right, then sea levels will rise many feet.
That's a big if. In 2005, a paper in Science, using satellite radar data, showed the ice sheet in East Antarctica was gaining mass, and argued that global warming was increasing the amount of snowfall there. A growing Antarctic ice sheet, the authors concluded, would slow the rate of sea level rise caused by the melting of ice in the Arctic and in Greenland.
However, another study published in Science in 2006 using data from computer models and ice cores, came to a nearly opposite conclusion, showing that "Antarctic precipitation is not mitigating global sea level rise as expected."
And then in January of this year a paper in Nature Geosciences used radar data to argue that glacial discharge in Antarctica is accelerating, leading the authors to claim that, overall, the ice mass of Antarctica is heading down, but conceding that "large uncertainties remain in the current and future contribution to sea level rise from Antarctica."
All of these studies are to be taken with a frozen grain of salt, Neumann believes, since so little is know about East Antarctica's climate history and effect on sea level. Huge and largely unexplored, this swath of the ice sheet sits like a great question mark at the bottom of the world.
"Nature is only doing one thing in East Antarctica," he says, "but we don't know what it is yet."
Climate Fingerprints Which is a primary reason that Neumann, an expert on ice flow and polar snow chemistry, is spending three weeks bumping along at six miles per hour (max speed) in a tank-like ice tractor. He's a member of the first scientific trip to East Antarctica since the 1960s, a joint US/Norwegian effort (http://traverse.npolar.no/) funded by the Norwegian Polar Institute and the US National Science Foundation. Neumann is traveling with the team for the first three weeks of a two-month expedition, following a curving 1,800-mile course across the remote Dronning Maud Land, headed for the South Pole (Professional video from the trip is available here [http://passporttoknowledge.com/polar-palooza/]).
Along the way—before getting ferried back to the coast by a German supply plane—Neumann and his colleagues dig pits in the snow and drill deep ice cores to be shipped back to the US Ice Core Lab in Denver. His studies of isotopes in the ice serve as a fingerprint of past climates. As snow crystals form in the atmosphere, the ratio of heavier isotopes of oxygen and hydrogen to lighter ones is determined by air temperature. These crystals fall and pile up for millennia, leaving layers of temperature-coded ice.
Some of Neumann's ice cores, 100-feet deep, will give him a picture of the last 200-300 years. Others, 300-feet deep, show the last 1,000 years. This history—read through measurements of the melted ice in a mass spectrometer back in a UVM lab—can't be determined by a high-flying satellite. You've got to go there.
"Is East Antarctic getting bigger or smaller" Neumann says as the satellite phone hisses and goes dead for the eighth time. "The ice we're collecting now gets us closer to a clear answer," he says, calling back a few moments later.
The ice cores give one glimpse of the ponderous forces that govern this continent. A full picture of what's happening in Antarctica can only be drawn by integrating how short-term changes, like accumulation rates of snow at the surface and annual temperature variability, play out against much longer-term changes, like response to the end of the last ice age and centuries-long movements in the miles-deep ice sheet.
"If you look at the data that was used in the 2006 Science paper, there is very little from the middle of East Antarctica,' he says. "Our ice cores are going to fill in some big holes in the map. And that should lead to more robust predictions," he says, about the shifting ice and shifty future that rests on Antarctica.
