21 September 2004
Antarctic Glaciers Accelerate in Wake of Ice Shelf Breakup
Antarctic glaciers respond rapidly to climate change, according to new evidence found by NSIDC, NASA, and IAA scientists. In the wake of the Larsen B Ice Shelf disintegration in 2002, glaciers in the Antarctic Peninsula have both accelerated and thinned en route to the Weddell Sea. The findings indicate that ice shelf breakup may rapidly lead to sea level rise.
In a paper published in Geophysical Research Letters, Ted Scambos and Jennifer Bohlander of NSIDC, Chris Shuman of the Oceans and Ice Branch at NASA's Goddard Space Flight Center, and Pedro Skvarca of the Instituto Antártico Argentino describe two- to six-fold increases in centerline speed of four glaciers feeding the now-collapsed section of the Larsen B Ice Shelf. They also describe elevation losses in three glaciers in the collapse area. The researchers used both Landsat 7 and ICESat satellite imagery in this study.
In the same issue of GRL, Eric Rignot of NASA's Jet Propulsion Laboratory and collaborators describe the same acceleration using Interferometric SAR from RADARSAT. Using their map of the flowspeed, they estimate that the glaciers ought to be thinning by tens of meters. ICESat elevation measurements by the Scambos team corroborate their prediction.
Ice shelves are thick platforms of ice that are fed by glaciers and float on the ocean. Ice shelf disintegration has no direct effect on sea level because the ice shelf has already displaced its own volume in seawater. In the wake of an ice shelf collapse, however, the resulting glacier acceleration can raise sea level by introducing a new ice mass into the ocean. Although glaciers on the Antarctic Peninsula are too small to significantly raise sea level, this research provides a glimpse of what could happen on a larger scale if other large ice shelves in Antarctica for example, the Ross Ice Shelf experienced similar warming. "This gives us a chance to watch an experiment before the consequences get serious," said Scambos. "Even though we don't see immediate evidence of ice shelf breakup on the Ross Ice Shelf, everything we've seen up to this point has occurred faster than we expected. The larger ice shelves in other parts of Antarctica could have real effects on the rate of sea level rise."
Scambos, T. A., J. A. Bohlander, C. A. Shuman, and P. Skvarca. 2004. Glacier acceleration and thinning after ice shelf collapse in the
Larsen B embayment, Antarctica. Geophysical Research Letters. doi:10.1029/2004GL020670.
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