Inland thinning on the Greenland ice sheet controlled by outlet glacier geometry

Abstract

Greenland’s contribution to future sea-level rise remains uncertain and a wide range of upper and lower bounds has been proposed. These predictions depend strongly on how mass loss—which is focused at the termini of marine-terminating outlet glaciers—can penetrate inland to the ice-sheet interior. Previous studies have shown that, at regional scales, Greenland ice sheet mass loss is correlated with atmospheric and oceanic warming. However, mass loss within individual outlet glacier catchments exhibits unexplained heterogeneity, hindering our ability to project ice-sheet response to future environmental forcing. Using digital elevation model differencing, we spatially resolve the dynamic portion of surface elevation change from 1985 to present within 16 outlet glacier catchments in West Greenland, where significant heterogeneity in ice loss exists. We show that the up-glacier extent of thinning and, thus, mass loss, is limited by glacier geometry. We find that 94% of the total dynamic loss occurs between the terminus and the location where the down-glacier advective speed of a kinematic wave of thinning is at least three times larger than its diffusive speed. This empirical threshold enables the identification of glaciers that are not currently thinning but are most susceptible to future thinning in the coming decades.

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Figure 1: Dynamic surface elevation change and mass loss.
Figure 2: Centreline profile of Kangilernata Sermia (KAN).
Figure 3: Péclet number running maxima and percentage unit volume loss.

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Acknowledgements

We would like to thank the Polar Geospatial Center for providing the WorldView stereo imagery. This work was funded by NASA Grant NNX12AP50G, by funding from the University of Texas Aerospace Engineering department, and a University of Texas Institute for Geophysics Postdoctoral Fellowship to T.C.B.

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D.F., T.C.B. and G.A.C. designed the study. D.F. created the WorldView DEMs, calculated catchment mass changes, and performed the kinematic wave analysis. D.F., T.C.B. and G.A.C. interpreted the results. N.J.K. and K.H.K. created the 1985 DEM. M.M. processed the mass-conserving bed for the study region. B.N. and M.v.d.B. provided downscaled SMB data. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Denis Felikson.

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The authors declare no competing financial interests.

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Felikson, D., Bartholomaus, T., Catania, G. et al. Inland thinning on the Greenland ice sheet controlled by outlet glacier geometry. Nature Geosci 10, 366–369 (2017). https://doi.org/10.1038/ngeo2934

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