Robert Roy Britt
LiveScience Managing Editor
LiveScience.com
Thu Nov 17, 6:02 PM ET A new study reveals one of the largest glaciers in Greenland is shrinking and speeding to the sea faster than scientists expected. If it continues, Greenland itself could become much smaller during this century and global seas could rise as much as 3 feet.
"The rates of change that we're observing are much higher than expected," said Ian M. Howat of the University of California, Santa Cruz. "If these rates of response continue, it is not unlikely that Greenland could shrink by several tens of percent this century."
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Since the 1970s, the front of Helheim stayed in the same place. Then it began retreating rapidly, moving back 4.5 miles from 2001 through this past summer. It has also grown thinner, from top to bottom, by more than 130 feet since 2001. And over these past four years, its trek to the sea has sped up from about 70 feet per day to nearly 110.
"This is a very fast glacier, and it's likely to get faster," Howat said. As the glacier's front retreats, its like a dam has been removed, and the inland portion can move more swiftly. The process has been seen in Antarctica by other researchers. A similar runaway effect has struck Greenland's Jakobshavn Isbrae glacier.
If the Helheim glacier thins beyond a critical point, it would simply float and rapidly disintegrate. In fact, the changes seen since 2001 were probably underway long before then but just not noticed. "Glaciers may have been thinning for over a decade," Howat said. "But it's only in the last few years that thinning reached a critical point and began drastically changing the glacier's dynamics."
LinkIcebergs dot coastal waters on the shores of Greenland in this view taken from an commercial airliner flying at 37,000 feet on September 2, 2004. Photo is taken just north of Godfarb on the west coast. Greenland's ice-cap has thickened in recent years despite predictions of a thaw triggered by global warming, according to a report in the journal Science on October 20, 2005. (Andy Clark/Reuters) --------------
The evidence keeps piling up. Glad someone is keeping close watch.