Science, 9 May 1997, Vol. 276, No. 5314, pp. 934–937 DOI: 10.1126/science.276.5314.934

Reports

North and Northeast Greenland Ice Discharge from Satellite Radar Interferometry

E. J. Rignot, ^* S. P. Gogineni, W. B. Krabill, S. Ekholm

Ice discharge from north and northeast Greenland calculated from satellite radar interferometry data of 14 outlet glaciers is 3.5 times that estimated from iceberg production. The satellite estimates, obtained at the grounding line of the outlet glaciers, differ from those obtained at the glacier front, because basal melting is extensive at the underside of the floating glacier sections. The results suggest that the north and northeast parts of the Greenland ice sheet may be thinning and contributing positively to sea-level rise.

E. J. Rignot, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, U.S.A.
S. P. Gogineni, Radar Systems and Remote Sensing Laboratory, The University of Kansas, 2291 Irving Hill Road, Lawrence, KS 66045-2969, U.S.A.
W. B. Krabill, NASA Goddard Space Flight Center, Wallops Flight Facility, Laboratory for Hydrospheric Processes, Wallops Island, VA 23337, U.S.A.
S. Ekholm, Kort and Matrikelstyrelsen, Geodetic Division, Rentemestervej 8, DK-2400 Copenhagen NV, Denmark
^* To whom correspondence should be addressed. e-mail: eric@adelie.jpl.nasa.gov

Link to abstract: http://www.sciencemag.org/cgi/content/abstract/276/5314/934
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Science, 17 February 2006, Vol. 311, No. 5763, pp. 986–990 DOI: 10.1126/science.1121381

Reports

Changes in the Velocity Structure of the Greenland Ice Sheet

Eric Rignot^1* and Pannir Kanagaratnam^2*

Using satellite radar interferometry observations of Greenland, we detected widespread glacier acceleration below 66° north between 1996 and 2000, which rapidly expanded to 70° north in 2005. Accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year. As more glaciers accelerate farther north, the contribution of Greenland to sea-level rise will continue to increase.

¹ Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 300-319, Pasadena, CA 91109–8099, U.S.A.
² Center for Remote Sensing of Ice Sheets (CReSIS), University of Kansas, Lawrence, KS 66045, U.S.A.

^* To whom correspondence should be addressed. e-mail: eric.rignot@jpl.nasa.gov (E.R), pannir@ku.edu (P.K.)

Link to abstract: http://www.scienceonline.org/cgi/content/abstract/311/5763/986
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Science, 20 June 2008, Vol. 320, No. 5883, pp. 1622–1625 DOI: 10.1126/science.1153929

Reports

Natural Variability of Greenland Climate, Vegetation, and Ice Volume During the Past Million Years

Anne de Vernal^* and Claude Hillaire-Marcel

The response of the Greenland ice sheet to global warming is a source of concern notably because of its potential contribution to changes in the sea level. We demonstrated the natural vulnerability of the ice sheet by using pollen records from marine sediment off southwest Greenland that indicate important changes of the vegetation in Greenland over the past million years. The vegetation that developed over southern Greenland during the last interglacial period is consistent with model experiments, suggesting a reduced volume of the Greenland ice sheet. Abundant spruce pollen indicates that boreal coniferous forest developed some 400,000 years ago during the "warm" interval of marine isotope stage 11, providing a time frame for the development and decline of boreal ecosystems over a nearly ice-free Greenland.

¹GEOTOP Geochemistry and Geodynamics Research Center–Université du Québec à Montréal, Case Postale 8888, succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada.

^* To whom correspondence should be addressed. e-mail: devernal.anne@uqam.ca

Link to abstract: http://www.sciencemag.org/cgi/content/abstract/320/5883/1622

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