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Holocene deceleration of the Greenland Ice Sheet

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Science  05 Feb 2016:
Vol. 351, Issue 6273, pp. 590-593
DOI: 10.1126/science.aab1702
  • Fig. 1 Constraints on the Holocene-averaged balance ice flux across the GrIS from dated radiostratigraphy.

    (A) Ice-equivalent depth of the 9-ka isochrone Embedded Image [determined as in (21)]. Black lines denote major ice-drainage basins (36). NS, Nares Strait. White triangles denote Camp Century (CC) and DYE-3 ice core sites. The magenta line represents the outer limit of reliable 1D modeling of depth-age relations to 9 ka (fig. S4). (B) Mean ice-equivalent accumulation rate over the past 9000 years Embedded Image. (C) Mean vertical strain rate within the 9- to 0-ka portion of the ice column Embedded Image.

  • Fig. 2 Holocene-averaged and modern surface speed across the GrIS.

    (A) Holocene-averaged surface speed Embedded Image (i.e., Holocene balance speed divided by shape factor) (fig. S5B). (B) Composite surface speed, Embedded Image, from 1995–2013 (37). (C) Change in surface speed between the present and the Holocene average Embedded Image.

  • Fig. 3 Dynamic Holocene deceleration of the GrIS.

    (A) Relative contribution of ice dynamics to change in surface speed Embedded Image. Gaps in coverage are due to positive Embedded Image values. (B) Modeled horizontal deceleration rate due to the LGP-Holocene viscosity contrastEmbedded Image over the past 1000 years, where Embedded Image is available (21). (C) Ratio of modeled to inferred dynamic deceleration rate Embedded Image. Gray contours outline regions where the mean 2003–2009 thickening rate was >10 cm year–1 (16).

Supplementary Materials

  • Holocene deceleration of the Greenland Ice Sheet

    Joseph A. MacGregor, William T. Colgan, Mark A. Fahnestock, Mathieu Morlighem, Ginny A. Catania, John D. Paden, S. Prasad Gogineni

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Figs. S1 to S9
    • Full Reference List

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