Sponge-Like Peat Bogs Could Offset Sea Level Rise

May 28, 2009 -- Like giant sponges draped across the land, peat bogs may soak up enough water to partially offset global sea level rise, according to a new study.

Worldwide, peatlands cover approximately 1.2 million square miles of land -- about 2 percent of the planet's land mass. The waterlogged ecosystem is most prevalent in the cool, moist climates of northern North America, Russia, the Tibetan Plateau, the British Isles, Scandinavia, and Patagonia.

For the most part, warming temperatures and shifting rain patterns expected from climate change are likely to dry up and deteriorate peat. But in the foothills of Mt. Denali in Alaska, Julie Loisel of Lehigh University and a team of researchers have found peatlands thriving. It's an unexpected discovery since the region doesn't appear to get enough rain to support such a sodden landscape.

The mountain's dwindling glaciers could be the answer. As global warming bears down on the high-altitude ice, melting has jumped considerably in the last few decades. That water is typically thought to run off into the ocean and contribute to sea level rise, but Loisel thinks the porous sphagnum moss that makes up most peat may be drinking in the excess moisture.

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"When people think of sea level rise, they just look at how much ice is lost and think it all goes right into the ocean," Loisel said. "What we want to stress here is that, wait, there's another place it can go."

Loisel presented her findings at the joint assembly of the American Geophysical Union in Toronto.

Peatlands are an enormously important part of the water cycle -- they store 10 percent of Earth's fresh water.

The team's finding in Alaska is preliminary -- they're not sure exactly how much the peatlands have expanded over the past century -- and it's not enough to impact global sea level much on its own. But if the trend holds wherever peat and glaciers reside in close proximity in the Tibetan Plateau, Patagonia, and elsewhere, the overall effect could change our understanding of how fast climate change will cause the oceans to swell.

"It's very provocative work," Paul Glaser of the University of Minnesota said. "It's possible that the peat is responding to some other climatic factors, and they'll (the team) have to do more work to firmly make the connection with glaciers. I'll be very interested to see what they do next."

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