Greenland's Ice Sheet: 2 of 2: "Whether or not we think the same processes are in place in Antarctica, we're not sure of that..." Joseph A. MacGregor, York University,Toronto, Ontaria, Canada.

Sep 16, 03:07 AM

AUTHOR.

(Photo:Herbert Ponting (1870–1935) Blue pencil.svg wikidata:Q127805

Description 

English: Robert Falcon Scott's Terra Nova. In the pack - a lead opening up.

Nederlands: Robert Falcon Scott's Terra Nova. In het pakijs - een uitweg opent zich.

Date December 1910

Source/Photographer Original photo print from Ponting's negatives. Private collection of Bruce Parker, London, Ontario, Canada.

Additional information 

English: Photo used in the book: Scott's Last Expedition..., 1913, Dodd, Mead, and Company, New York. Volume I, page 48.

Nederlands: Foto gebruikt in het boek: Scott's Last Expedition..., 1913, Dodd, Mead, and Company, New York. Deel I, bladzijde 48. )

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Greenland's Ice Sheet: 2 of 2: "Whether or not we think the same processes are in place in Antarctica, we're not sure of that..."  Joseph A. MacGregor, York University,Toronto, Ontaria, Canada.

http://science.sciencemag.org/content/351/6273/590.short

"Holocene deceleration of the Greenland Ice Sheet"

Joseph A. MacGregor1,*, William T. Colgan2,†, Mark A. Fahnestock3, Mathieu Morlighem4, Ginny A. Catania1,5, John D. Paden6, S. Prasad Gogineni6

1Institute for Geophysics, The University of Texas at Austin, Austin, TX 78758, USA.

2Geological Survey of Denmark and Greenland, Copenhagen DK-1350, Denmark.

3Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.

4Department of Earth System Science, University of California, Irvine, Irvine, CA 92697, USA.

5Department of Geological Sciences, The University of Texas at Austin, Austin, TX 78712, USA.

6Center for Remote Sensing of Ice Sheets, The University of Kansas, Lawrence, KS 66045, USA.

↵*Corresponding author. E-mail: joemac@ig.utexas.edu

↵† Present address: Department of Earth and Space Science and Engineering, York University, Toronto, Ontario M3J 1P3, Canada.

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Science 05 Feb 2016:

Vol. 351, Issue 6273, pp. 590-593

DOI: 10.1126/science.aab1702

Abstract "Recent peripheral thinning of the Greenland Ice Sheet is partly offset by interior thickening and is overprinted on its poorly constrained Holocene evolution. On the basis of the ice sheet’s radiostratigraphy, ice flow in its interior is slower now than the average speed over the past nine millennia. Generally higher Holocene accumulation rates relative to modern estimates can only partially explain this millennial-scale deceleration. The ice sheet’s dynamic response to the decreasing proportion of softer ice from the last glacial period and the deglacial collapse of the ice bridge across Nares Strait also contributed to this pattern. Thus, recent interior thickening of the Greenland Ice Sheet is partly an ongoing dynamic response to the last deglaciation that is large enough to affect interpretation of its mass balance from altimetry.

“…The interior of the Greenland Ice Sheet is growing thicker, in contrast to the thinning that is occurring at its edges. Why? MacGregor et al. conclude that more snow is accumulating and that the ice in the interior is flowing more slowly than it did thousands of years ago (see the Perspective by Hvidberg). During the last glacial period, higher rates of atmospheric dust deposition produced softer ice, which flowed more readily than cleaner ice. During most of the Holocene, though, atmospheric dust concentrations were lower, and the less-dusty ice that formed was stiffer, meaning it did not flow or thin so rapidly. Thus, the thickening seen today in the central regions of Greenland is partly a response to changes in ice rheology that occurred thousands of years ago." -- Joseph A. MacGregor, William T. Colgan, Mark A. Fahnestock, Mathieu Morlighem, Ginny A. Catania, John D. Paden, S. Prasad Gogineni "Abstract: Recent peripheral thinning of the Greenland Ice Sheet is partly offset by interior thickening and is overprinted on its poorly constrained Holocene ...