Saturday, August 13, 2011

Polar climate change may lead to ecological change

Penn State News: Ice and frozen ground at the North and South Poles are affected by climate-change-induced warming, but the consequences of thawing at each pole differ due to the geography and geology, according to a Penn State hydrologist.

"The polar regions, particularly the Arctic, are warming faster than the rest of the world," Michael N. Gooseff, associate professor of civil and environmental engineering, told attendees Aug. 11, at the 96th annual meeting of the Ecological Society of America in Austin, Texas. "As a consequence, polar ecosystems respond directly to changes in the earth systems at the poles."

These changes, though different at each pole, could be significant in their effects on not only the local environment, but also globally. While the central part of the Arctic is composed of ice over water, northern Canada, Alaska, Siberia and Greenland all have landmasses within the Arctic Circle. The associated land and water ecosystems are affected by melting ice and thawing soils, but in Antarctica, where much of the ice overlays a continent, the warming alters streams, lakes and the tiny plants and animals that live there.

"Our focus on the north is in part because it is inhabited, but it is also because the ice there is more vulnerable," said Gooseff. "Temperatures and snow and rain across the tundra shifts annually and seasonally. We know that fall is beginning later than it once did."

In the Arctic, where there is more immediate feedback from the higher temperatures, the warming is degrading permafrost, the layer of the ground that usually remains frozen during annual thawing events. This causes creation of a boggy, uneven landscape with a disturbed surface. Subsequent rain or snowmelt can erode this surface carrying silt and sediment into bodies of water, changing the paths of rivers and streams. Debris flows also are a common occurrence in degraded permafrost areas.

...Because there is so much permanent ice in Antarctica, the annual impact of increased temperatures on its environment is slower than in the Arctic. The huge expanse of white ice reflects some of the heat energy into the atmosphere. "We expect in the next several decades that we will see the Antarctic start to warm up," said Gooseff...

Bull Pass in the Dry Valleys of southern Victoria Land. The Dry Valleys extend over 1,500 square miles and are mostly devoid of snow and ice. Photo by Josh Landis of the National Science Foundation

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