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Humboldt Field Research Institute

Posted March 8, 1999

Antarctic lakes offer climate clues

Meredith Kelly started her undergraduate work at Tufts University knowing she was headed for a career in science, but not uncertain about which field. After taking one class in geology, she knew.

Kelly earned a double major in geological sciences and environmental studies at Tufts. Her senior thesis was on ancient glacial lakes that formed in New England as ice retreated through North America. In New England, ancient glacial lake sediments provide records of climate for as much as 4,000 years during the last deglaciation.

Now in her graduate work at UMaine, Kelly continues to study glacial lakes, this time in Antarctica.

“The neat thing about climate study is the ability to develop records from all over the world and figure out what was happening on a global scale,” says Kelly, who is conducting research with one of the world leaders in Quaternary studies, George Denton.

“Determining whether global change occurred simultaneously in different hemispheres, or whether the changes were out of phase, points to mechanisms driving climate.”

In October 1997, Kelly and two other women – undergraduate Amy Benoit and Ph.D. candidate Brenda Hall (who earned a Ph.D. in 1996 and is now a post-doc at Woods Hole Oceanographic Institute) – were airlifted by helicopter from McMurdo base station in Antarctica to a dry valley called Victoria Valley 150 kilometers away.

Kelly spent three months in the field mapping the surficial deposits of the valley. The first month, she was with the other two women; the second month, she and Benoit worked alone. Denton joined the young scientists for the last three weeks of research.

“It was wonderful. And it was intense,” says Kelly of her Antarctic experience and the research that took her there. “I expected it to be cold and it was, below freezing most of the time. In Victoria Valley, the sun went behind a ridge at night, and it was much colder without direct sunlight. A strong, persistent wind from the coast, 35 kilometers away, added to the cold. The valley is a polar desert.

“We didn't have to worry abut getting wet because it rarely snowed. We got snow and ice to melt for water from a permanent snow bank, about five minutes from camp. We slept in eight-foot-square canvas tents and used a two-burner Coleman stove to cook. One of our best meals in camp was pizza. We packed our lunches as we worked long days away from camp. It felt like I was always working, even in camp at night picking through the samples gathered that day.

“The work was really challenging. I had never really been in the field on my own. It was an experience to be able to see an entire valley and know that my job was to make a map of everything that was there and to try to figure out the environments in which it was deposited. The project was a little overwhelming in the beginning. We were to map everything in a valley that took three hours to walk across.”

Kelly's research, the focus of her thesis, is part of Denton's ongoing research in the Antarctic. “George has been working there for a long time, piecing together a well-knit story about what happened there climatically for the past 20 million years,” says Kelly. “Two other graduate students from Quaternary and Geology are down there now conducting research.”

In Victoria Valley, Kelly found evidence of large proglacial lakes, some with levels as high as 700 meter elevation, that repeatedly occupied the valley throughout the past 10 million years. Today in the Antarctic, the lake levels in Victoria Valley are at approximately 400 meter elevation.

Many of the deposits were mapped in the `60s and early `70s and were interpreted to be glacial moraines (transported directly by glacial ice). Using a new model of sediment deposition developed by Dr. Chris Hendy at the University of Waikato in New Zealand, Kelly interpreted these deposits to have been transported and deposited by lake ice on a proglacial lake.

“In the `80s, some had the idea that the East Antarctic Ice Sheet collapsed during the Pliocene (3 million-5 million years ago), a time when global climate was slightly warmer than present. Such findings would imply that the ice sheet is not stable during periods of global warmth, and that if the present climate warms, the ice sheet may collapse, causing a 60 meter rise in eustatic sea level. Such proglacial lakes only exist in cold, polar climates. Therefore, if there is evidence for the existence of such lakes throughout the past 10 million years, that would preclude a collapse of the EAIS during the Pliocene.

“Today in terms of global warming, it is important to determine if the ice sheet is stable or not. We found evidence that it has been a polar desert, and that the EAIS has been stable for a long time.”

Kelly says such a unique opportunity to contribute to research like this as a student is empowering. “You feel that all the time you've put into the work and thesis is meaningful and will be used as reference by other people. Now I'm working on getting an article published in a peer review journal.”

Kelly finished her thesis in November, and this semester is working as a teaching assistant. She has been offered a Ph.D. position at the University of Bern and will leave for Switzerland at the end of May. There she will map the glacial features in the French Alps to begin to put together a climate history.

“Glaciers are influenced by climate and are a key to unraveling past global change. If we can piece together clues such as glacial erosional features and deposits, we can begin to develop a history of climate.”

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