The Scientist Who Stays out in the Cold
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The Scientist Who Stays Out in the Cold by Lonny Lippsett pending a month working in subzero only natural that the focus of her research conditions in Antarctica might not would be someplace cold: the massive soundS like fun to most people, but to West Antarctic Ice Sheet. Sarah Das, WHOI Alison Criscitiello Alison Criscitiello, it’s heaven. Scientists have concerns that warming “I definitely have a thing for cold plac- ocean temperatures are accelerating the es,” said Criscitiello, a graduate student in flow of ice from the continental ice sheet Bay—the Pine Island and Thwaites the MIT/WHOI Joint Program. “I love into the ocean, which could raise global sea Glaciers—have been accelerating and being cold. I love it.” levels. In the Amundsen Sea coastal region losing mass over the past 25 years. During Her love of cold places has led her to where Criscitiello works, winds are driving the same time, sea ice that forms in the the summits of many high, ice-covered warming deep-ocean waters onto the con- Amundsen Sea has declined significantly. mountains. An accomplished climber, tinental shelf and beneath the ice shelves Criscitiello is exploring the relationship she has worked as a National Park Service extending from glaciers into the ocean. between the two phenomena, as well as climbing ranger and a mountain guide Melting from below, the glacial fronts are another factor that may be playing an for a private company. In 2010 she led two breaking up more easily, draining more ice important role: polynyas. friends on the first all-women climb of into the Amundsen Sea. Polynyas, a Russian word meaning Pinnacle Peak, a 6,930-meter (22,736-foot) In Criscitiello’s study area, two large “natural ice holes,” are patches of open mountain in the Himalayas. So it was outlet glaciers emptying into Pine Island ocean surrounded by sea ice. They form Sarah Das, WHOI 14 OCEANUS MAGAZINE Vol. 49, No. 2, Spring 2012 | www.whoi.edu/oceanus STUDENT AT WORK when warmer waters upwell to the surface, or when ocean currents or winds traveling offshore push sea ice away from the coast, Amundsen Sea leaving ice-free areas. Polynyas can have big impacts on local Burke Island climate and on the generation of sea ice in winter. The areas of open water allow heat olorado, Boulder exchange between the ocean and atmo- C sphere. They also affect ocean circulation. niversity of U Frozen clues enter, enter, C How do polynyas, sea ice, and ice sheets weave together? And can we find new ways B-22A of extending records of their behavior in Iceberg Pine Island the past so that we can understand their Bay interplay on longer time scales? To answer ational Snow and Ice Data those questions, scientists need to see the N full tapestry, and therein lies the problem. Thwaites “Satellite images have captured sea-ice Glacier Pine Island behavior around Antarctica over the past Glacier 20 years, but before that, we really have very little idea what sea ice looked like,” Image/photo courtesy of the Criscitiello said. In the Amundsen Sea coastal region, warming To put sea-ice changes into context, Criscitiello said. “So MSA may be an seawater is being driven beneath ice shelves Criscitiello is trying to reconstruct the indirect recorder of sea-ice and polynya extending from glaciers into the bay. Melting history of sea ice off West Antarctica— variability off the coast.” from below, the fronts of glaciers are weaken- a history that may be recorded within “The way to extract this record from ing. In the past 25 years, two large outlet gla- layers of the ice sheet itself. the ice sheet is to drill or dig,” she said. ciers emptying into Pine Island Bay—the Pine “In the austral spring and summer when “We hand-dig snow pits about 10 feet Island and Thwaites Glaciers—have been flow- sea ice breaks up, it is the first time that deep. To get samples from further back in ing faster and losing more ice to the ocean. year that the upper part of the ocean sees time, we use a mechanized ice-core drill.” sunlight,” she explained. “All the little The ice cores, up to 377 feet deep, rep- a nearly vertical ice wall and a route where plants of the sea—the phytoplankton— resent about 200 years of ice accumulation. an avalanche appeared likely. bloom, and they release a chemical that Criscitiello cuts the cores into narrow slices “The three of us sat there beneath this eventually becomes methanesulfonic acid, corresponding to specific periods of time nearly vertical ice face knowing it was the or MSA, into the atmosphere. This MSA and measures the concentrations of MSA only way we could go up,” she said. “It was is carried by the wind over the ice sheet in each slice. the first time I ever had the thought: ‘Oh and precipitated as snow. So year after no, maybe I’m in over my head.’ ” It took year, bloom after bloom, and snowfall after Uncertain terrains two difficult days but they made it to the snowfall, the MSA gets laid down in layers When she started her research, Crisci- summit, high above a sea of clouds. on the ice sheet.” tiello did not know whether all her hard Back in Antarctica, the story told by The less sea ice, the more open water work would lead to a dead end. Scientists the MSA concentrations in Criscitiello’s there is, the bigger the phytoplankton trying the MSA method elsewhere have ice-sheet records has bolstered her confi- bloom, and the more MSA produced. had mixed results; MSA preserves a re- dence that ice-core records from this Even with limited sunlight in wintertime, liable record of sea-ice behavior in some dynamic region may provide a reliable phytoplankton can still bloom in polynyas places, but not in others, probably because proxy for reconstructing how sea ice and and release the chemical that becomes of differences in local wind and precipita- polynyas in the Amundsen Sea and Pine MSA and ends up in the ice-sheet layers, tion patterns throughout the year, among Island Bay have varied in the era before other factors. Thus, scientists must validate satellites. Alison Criscitiello removes the inner barrel MSA ice-core records from any new site to “Sometimes you have to just try things,” of a drill containing an ice core from the West ensure that they tell a reliable story about she said, “even though you have no idea Antarctic Ice Sheet. Snow falls atop the ice sea ice in a particular location. what the outcome is going to be.” sheet in annual layers, so the deeper you “It was possible that this method was drill, the further back in time you go. The not going to work here,” she said. But Ari Daniel Shapiro contributed to this report. graduate student is analyzing a chemical she went after it—just as she and her compound in the ice to reconstruct how sea friends had in 2010 when they reached This research was funded by the Department of ice has changed over hundreds of years in their final ascent of Pinnacle Peak at Energy, the National Science Foundation, and the the Pine Island Bay region. 18,000 feet. They faced a choice between National Aeronautics and Space Administration. Woods hoLE OCEANOGRAPhiC INSTITUTioN 15.