Ice Wedge Melting Changing The Terrain Across The Arctic - Could Create A Far Drier North
Ice wedges, a common subsurface feature in permafrost landscapes, appear to be rapidly melting throughout the Arctic, according to a new study published today in the journal Nature Geoscience. The wedges, which can be the size of a house, gradually formed over hundreds or even thousands of years as water seeped into permafrost cracks. On the ground surface, they form polygon shapes roughly 15-30 meters wide—a defining characteristic of northern landscapes. The micro-topographic features of ice wedge polygons affect drainage, snow distribution and the general wetness or dryness of a landscape.
Anna Liljedahl, an assistant professor at the University of Alaska Fairbanks' Water and Environmental Research Center, and her co-authors gathered information about the types of ice-wedge polygons and how they changed over time across the Arctic. They collected the information while performing various other permafrost studies. Although these regions contain "cold permafrost," with an overall average temperature of about 7 degrees Fahrenheit, surface thawing still occurred at all of the 10 study sites.
Ice wedge degradation has been observed before in individual locations, but this is the first study to determine that rapid melting has become widespread throughout the Arctic. "Here we're combining observations from people working in the field across the Arctic—Russia, Canada and Alaska—where we're seeing the same ice wedge melting phenomenon," said Liljedahl, the lead author of the study.
Such thawing could bring significant changes to the hydrology of much of the Arctic as it alters the ground-surface topography. Melting of ice wedge tops makes the ground that surrounds the polygons subside, which in turn allows drainage of ice-wedge polygon centers. This can create a connective drainage system that encourages runoff and therefore an overall drying of the landscape.
EDIT
http://phys.org/news/2016-03-degrading-ice-wedges-reshape-arctic.html
