Loss of 'world's largest wetland' could tip ocean balance
April 17, 2012
Once thought to be too harsh and inhospitable to support any living thing, the ice sheets are now known to be a gigantic reservoir of microbial life.
By Cheryl Katz
The Daily Climate
BOZEMAN, Mont. – In addition to being a sanctuary for somnolent microbes from the past, the polar glaciers are an important habitat for a large array of active bacterial communities making their homes in and under the ice. Some are psychrophiles, or cold-lovers, that flourish at near-freezing temperatures and die back as they heat up. Others tolerate the cold, but do best in a balmier climate.
John Priscu, a microbial ecologist at Montana State University, describes the vast watery areas beneath Antarctica as "the world's largest wetland." There are no red-winged blackbirds or cattails, he said, "but there's microbes that do biochemistry… And since it's dark biochemistry, they get their energy from minerals. So they eat rocks."
The organisms weather rocks by stripping out elements such as iron and sulfur, oxidizing them to utilize the energy released from broken chemical bonds, then spitting the transformed minerals back into the water. This process is important for regulating marine minerals and ions, and loss of subglacial wetlands could upset the oceans' delicate geochemical balance, he said.
The threat to the oceans is becoming increasingly critical as the polar ice melt accelerates. Recent NASA satellite measurements show that throughout the past two decades, the ice sheets in Greenland and Antarctica lost considerably more mass each year than they did the year before. Antarctica is now losing more than 24 cubic miles of ice every year – enough to cover every inch of Arizona in ice a foot deep. And measurements of Arctic sea ice by the National Snow and Ice Data Center show that the summer 2011 ice cover was close to its lowest since satellite tracking began in 1979.
"With all this melt, you're flushing all kinds of things into the oceans that we haven't seen before," said Christine Foreman, a Montana State University microbial ecologist who spent last summer studying bacteria in streams and lakes atop Greenland's thawing glaciers, another potential hot spot for microbial life. Foreman was amazed at the amount of slush and running water she saw on the ice sheet, possibly draining loads of organic matter into the nearby fjords and sea.
"You've got more and more carbon coming into these systems," she said. “We don’t know whether we are going to change the balance of things because of all these new inputs that are happening. And they’re happening pretty rapidly."
© Cheryl Katz, 2012. All rights reserved.
Cheryl Katz is a freelance reporter based in California. DailyClimate.org is a nonprofit news service covering climate change. To reach editor Douglas Fischer, email dfischer [at] DailyClimate.org
Photos, from top: Christine Foreman roped in and ready to sample meltwater lakes on Greenland, courtesy Foreman Research Group/Montana State University. Ice core samples melting under vacuum for analysis courtesy Anais Orsi/WAIS Divide
On the web: NASA information on global ice sheets
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