Abstract
The bed topography beneath the Greenland ice sheet controls the flow of ice and its discharge into the ocean. Outlet glaciers move through a set of narrow valleys whose detailed geometry is poorly known, especially along the southern coasts1,2,3. As a result, the contribution of the Greenland ice sheet and its glaciers to sea-level change in the coming century is uncertain4. Here, we combine sparse ice-thickness data derived from airborne radar soundings with satellite-derived high-resolution ice motion data through a mass conservation optimization scheme5. We infer ice thickness and bed topography along the entire periphery of the Greenland ice sheet at an unprecedented level of spatial detail and precision. We detect widespread ice-covered valleys that extend significantly deeper below sea level and farther inland than previously thought. Our findings imply that the outlet glaciers of Greenland, and the ice sheet as a whole, are probably more vulnerable to ocean thermal forcing and peripheral thinning than inferred previously from existing numerical ice-sheet models.
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References
Bindschadler, R. et al. Ice-sheet model sensitivities to environmental forcing and their use in projecting future sea-level (the SeaRISE project). J. Glaciol. 59, 195–224 (2013).
Nick, F. M. et al. Future sea-level rise from Greenland’s main outlet glaciers in a warming climate. Nature 497, 235–238 (2013).
Howat, I. M., Joughin, I., Fahnestock, M., Smith, B. E. & Scambos, T. A. Synchronous retreat and acceleration of southeast Greenland outlet glaciers 2000–06: Ice dynamics and coupling to climate. J. Glaciol. 54, 646–660 (2008).
IPCC-AR4 Fourth Assessment Report: Climate Change 2007: The AR4 Synthesis Report (IPCC, 2007)
Morlighem, M. et al. A mass conservation approach for mapping glacier ice thickness. Geophys. Res. Lett. 38, L19503 (2011).
Evans, S. & Robin, G. d. Q. Glacier depth-sounding from air. Nature 210, 883–885 (1966).
Bamber, J., Layberry, R. & Gogineni, S. A new ice thickness and bed data set for the Greenland Ice Sheet: 1. Measurement, data reduction, and errors. J. Geophys. Res. 106, 33773–33780 (2001).
Rignot, E. & Mouginot, J. Ice flow in Greenland for the International Polar Year 2008–2009. Geophys. Res. Lett. 39, L11501 (2012).
Holt, J., Peters, M., Kempf, S., Morse, D. & Blankenship, D. Echo source discrimination in single-pass airborne radar sounding data from the dry valleys, Antarctica: Implications for orbital sounding of Mars. J. Geophys. Res. 111, E06S24 (2006).
Jezek, K., Wu, X., Paden, J. & Leuschen, C. Radar mapping of Isunnguata Sermia, Greenland. J. Glaciol. 59, 1135–1146 (2013).
Forster, R. R. et al. Extensive liquid meltwater storage in firn within the Greenland Ice Sheet. Nature Geosci. 7, 95–98 (2014).
Deutsch, C. & Journel, A. GSLIB Geostatistical Software Library and User’s Guide 2nd edn (Oxford Univ. Press, 1997).
Gogineni, P. CReSIS RDS Data (2012); http://data.cresis.ku.edu/
Howat, I., Negrete, A. & Smith, B. The Greenland Ice Mapping Project (GIMP) land classification and surface elevation datasets. Cryosphere Discuss. 8, 453–478 (2014).
Morlighem, M. et al. High-resolution bed topography mapping of Russell Glacier, Greenland, inferred from operation Ice Bridge data. J. Glaciol. 59, 1015–1023 (2013).
Bamber, J. L. et al. A new bed elevation dataset for Greenland. Cryosphere 7, 499–510 (2013).
Seroussi, H. et al. Ice flux divergence anomalies on 79north Glacier, Greenland. Geophys. Res. Lett. 38, L09501 (2011).
Durand, G., Gagliardini, O., Favier, L., Zwinger, T. & le Meur, E. Impact of bedrock description on modeling ice sheet dynamics. Geophys. Res. Lett. 38, L20501 (2011).
Kessler, M. A., Anderson, R. S. & Briner, J. P. Fjord insertion into continental margins driven by topographic steering of ice. Nature Geosci. 1, 365–369 (2008).
Harbor, J. Numerical modeling of the development of U-shaped valleys by glacial erosion. Geol. Soc. Am. Bull. 104, 1364–1375 (1992).
Ekholm, S., Keller, K., Bamber, J. & Gogineni, S. Unusual surface morphology from digital elevation models of the Greenland Ice Sheet. Geophys. Res. Lett. 25, 3623–3626 (1998).
Swift, D. A., Persano, C., Stuart, F. M., Gallagher, K. & Whitham, A. A reassessment of the role of ice sheet glaciation in the long-term evolution of the East Greenland fjord region. Geomorphology 97, 109–125 (2008).
Rignot, E., Koppes, M. & Velicogna, I. Rapid submarine melting of the calving faces of West Greenland glaciers. Nature Geosci. 3, 187–191 (2010).
Holland, D., Thomas, R., De Young, B., Ribergaard, M. & Lyberth, B. Acceleration of Jakobshavn Isbrae triggered by warm subsurface ocean waters. Nature Geosci. 1, 659–664 (2008).
Joughin, I., Smith, B., Howat, I., Scambos, T. & Moon, T. Greenland flow variability from ice-sheet-wide velocity mapping. J. Glaciol. 56, 416–430 (2010).
Howat, I. M. & Eddy, A. Multi-decadal retreat of Greenland’s marine-terminating glaciers. J. Glaciol. 57, 389–396 (2011).
Wu, X. et al. Ice sheet bed mapping with airborne SAR tomography. IEEE Trans. Geos. Rem. Sens. 49, 3791–3802 (2011).
Ettema, J. et al. Higher surface mass balance of the Greenland Ice Sheet revealed by high-resolution climate modeling. Geophys. Res. Lett. 36, 1–5 (2009).
Schenk, T. & Csatho, B. A new methodology for detecting ice sheet surface elevation changes from laser altimetry data. IEEE Trans. Geosc. Rem. Sens. 50, 3302–3316 (2012).
Acknowledgements
This work was performed at the University of California Irvine and the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA, Cryospheric Sciences Program grant NNX12AB86G. CReSIS data products are from NSF grant ANT-0424589 and NASA grant NNX10AT68G. Ice-thinning rates are from NCAR/EOL funded by NSF. SMB data is from M. van den Broeke, University of Utrecht, The Netherlands. The bathymetry data described in Supplementary Information are a product of Grant 2980 from the Gordon and Betty Moore Foundation.
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M.M. developed the algorithm and led the calculations. H.S. assisted in implementing the algorithm. J.M. provided velocity mapping. All authors contributed to the writing of the paper.
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Morlighem, M., Rignot, E., Mouginot, J. et al. Deeply incised submarine glacial valleys beneath the Greenland ice sheet. Nature Geosci 7, 418–422 (2014). https://doi.org/10.1038/ngeo2167
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DOI: https://doi.org/10.1038/ngeo2167
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