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Chasing glaciers in Greenland

August 7, 2013
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University of Michigan professor Sara Aciego researches glacial meltwater in Greenland.

Sarah Aciego doesn’t anticipate her research in Greenland will be as dangerous as her fieldwork in Antarctica, where finding shelter within seconds during a sudden storm meant the difference between life or death. But the assistant professor in the Department of Earth and Environmental Sciences does know this trip could be just as important as her Antarctic fieldwork—if not more.

Her new method of studying glacial meltwater will yield data that hasn’t been accessible to scientists before and will help paint a more detailed picture of climate change. Glacial melting occurs where an ice sheet is in contact with the earth. As the pace of global warming accelerates, scientists like Aciego are trying to learn more about this process.

“We can’t climb under the glacier to see what’s happening under there,” Aciego said, “so we’ll be collecting meltwater samples very close to the outlet, where it enters the sea.”

Because meltwater starts out with almost no impurities, Aciego’s samples will help determine how many minerals and nutrients the meltwater picks up on its way to the sea. Aciego’s data can then be used by oceanographers tracking the effect of global warming on the world’s oceans.

The nutrients in glacial meltwater are crucial for the growth of microorganisms such as plankton, which absorb large amounts of carbon dioxide from the atmosphere and also produce as much as half of the oxygen humans breathe. As melting speeds up, scientists don’t exactly know what will happen to the production of plankton, carbon dioxide and oxygen over time. It’s a critical question to answer as atmospheric gases seriously affect human life and health.

Over the next five years, Aciego will collect meltwater from three key sites in Greenland where the ice sheet is melting faster than elsewhere on the island. The ice sheet is currently a mile thick in most places, and consists of layers of ice that have accumulated over at least 100,000 years and possibly 2.5 million years. But satellite data shows the Greenland ice sheet is melting faster than ever before in the geophysical record—faster than any other ice sheet on Earth, revealing soil and rock that has not been exposed since the last interglacial period, about 127,000 years ago.

Aciego’s research has the potential to provide scientists from many disciplines with key data to help correlate and more precisely align an all-encompassing picture of climate change. It would be prohibitively expensive without the prestigious five-year $875,000 grant that she won from the Packard Fellowship for Science and Engineering last fall. The grant – often a predictor of which researchers will make a significant impact in their field – is designed to encourage promising young scientists to think big without having to worry about getting fast results.

U-M nominated Aciego after she pioneered a new chemical method to determine the age of dust trapped in glacial ice, in conjunction with her work in Antarctica.

“This is a huge honor. When I look at past recipients, I feel very humble,” Aciego said.

Now, her research, teaching, conferences and lab where she supervises an on-campus research team of 12 are so all-consuming that she has little time to get outside. But she believes that the relevancy of her work makes the tradeoff worthwhile.

Government leaders, she said, will eventually have to contend with the dire projections she and other climate scientists are making.

“Global warming is leading to melting of these large ice sheets, which is raising sea level at a rate and magnitude that is expected to displace millions of people. And unfortunately, most of them are the poorest people in the world, who won’t be able to help themselves.

“We can see from the geological record that Earth has always gone through long periods of warming and cooling, each lasting tens of thousands or hundreds of thousands of years,” she added. “The glaciers have expanded and receded as part of this cyclical process.”

But Aciego said she and almost all scientists in related disciplines are concerned that Earth’s current warming trend is unprecedented for its speed, and the results are uncertain.

“We can already predict a one-meter seawater rise” within the next 100 years,  Aciego said. “If this were happening over a couple thousand years, as in the past, people would have time to migrate. Ecosystems would have time to adjust.

She said human influences are changing Earth’s systems in ways that we currently cannot predict. “Meanwhile, we’ll likely have more extreme weather events like Hurricane Sandy,” she said. “I fear we just don’t have the time or tools to mitigate the consequences.”

A version of this story was first published on LSA Today

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