Clark University scientists report first satellite-based quantifications of Antarctic ice sheet surface melt

Tuesday, December 3, 2013
Satellite image shows large (multi-kilometer scale) melt ponds and streams on the George VI ice shelf on the Antarctic Peninsula. These were taken by the WorldView-1 satellite. (Copyright: DigitalGlobe).

Satellite image shows large (multi-kilometer scale) melt ponds and streams on the George VI ice shelf on the Antarctic Peninsula. These were taken by the WorldView-1 satellite. (Copyright: DigitalGlobe).

 

For the first time, scientists are able to use satellite observations to quantify the amount of melt occurring across the surface of the Antarctic ice sheet, according to a paper recently published in Geophysical Research Letters, a journal of the American Geophysical Union. Clark University Ph.D. student (and NASA Earth and Space Science Fellow) Luke D. Trusel, of the Graduate School of Geography, is the paper’s lead author.

In “Satellite-based estimates of Antarctic surface meltwater fluxes” (funded by NASA’s Cryospheric Sciences Program), Trusel and co-authors – including Karen E. Frey, associate professor of geography at Clark – report on novel research results that hold important implications in understanding the strength and variability of melt across the Antarctic ice sheet, its drivers, and its resulting consequences. In particular, the new satellite observations highlight important cryosphere-climate interactions and processes leading to melt on the Antarctic Peninsula, a climatically sensitive region recently characterized by significant warming and large-scale ice shelf collapses.

For the Larsen C ice shelf on the Antarctic Peninsula, our new satellite results document persistent and intense melting that is among the highest melting occurring in Antarctica today,” Trusel writes. “These observations contribute to a growing understanding of the importance of föhn winds in this region, which flow downslope from the nearby Antarctic Peninsula mountains. We are able to quantify the resulting intense melt and find that the pattern of melt observed on Larsen C nearly mirrors observations of thinning, while also suggesting that existing melt ponds and streams on this ice shelf are likely to spread.”

A penguin navigates melt ponds in a photo taken during a 2010-2011 Antarctic field campaign. (Courtesy: Luke D. Trusel)

A penguin navigates melt ponds in a photo taken during a 2010-2011 Antarctic field campaign. (Courtesy: Luke D. Trusel)

“Continued monitoring of atmospheric, oceanic, and glaciological conditions across these ice shelves is imperative to assessing their future stability, and ultimately Antarctic contributions to sea level,” Trusel stresses.

Today, most Antarctic surface melt refreezes in place and thus does not directly add to rising sea level, according to the report. However, surface melting on Antarctic ice shelves (the floating, marine portions of the continental ice sheet) has been linked to multiple ice shelf collapses on the Antarctic Peninsula over the last several decades.  A notable example is the disintegration of the Larsen B ice shelf in 2002, where the Rhode Island-sized ice shelf broke up and capsized into the ocean over the course of several weeks. The establishment and drainage of meltwater ponds on the surface of this ice shelf is thought to have played an integral role its ultimate demise.  Importantly, this event reduced back-stresses on the glaciers once flowing into the ice shelf and resulted in their pronounced acceleration and direct contribution to sea level rise.

In addition to its role in ice shelf stability via melt ponds, surface melt observations offer an important record of climate and atmospheric variability across Antarctica, the authors note.  Recent studies have shown that atmospheric warming and associated melt may be resulting in changes to outlet glaciers in Antarctica.  Furthermore, as the surrounding ocean also impacts Antarctica, it is necessary to quantify surface melt in order to decipher the relative influence of oceanic versus atmospheric factors in driving observed changes such as ice shelf thinning and outlet glacier change.

Along with Trusel and Frey, co-authors of “Satellite-based estimates of Antarctic surface meltwater fluxes” include: Sarah B. Das, associate scientist of geology and geophysics at the Woods Hole Oceanographic Institution; Peter Kuipers Munneke, research scientist in the Ice and Climate research group at the Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University;  and Michiel R. van den Broeke, professor of polar meteorology at Utrecht University.

Founded in 1887 in Worcester, Massachusetts, Clark University is a small, liberal arts-based research university addressing social and human imperatives on a global scale. Nationally renowned as a college that changes lives, Clark is emerging as a transformative force in higher education today. LEEP (Liberal Education and Effective Practice) is Clark’s pioneering model of education that combines a robust liberal arts curriculum with life-changing world and workplace experiences. Clark’s faculty and students work across boundaries to develop solutions to complex challenges in the natural sciences, psychology, geography, management, urban education, Holocaust and genocide studies, environmental studies, and international development and social change. The Clark educational experience embodies the University’s motto: Challenge convention. Change our world. www.clarku.edu

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