Research ArticleCLIMATOLOGY

Stabilizing the West Antarctic Ice Sheet by surface mass deposition

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Science Advances  17 Jul 2019:
Vol. 5, no. 7, eaaw4132
DOI: 10.1126/sciadv.aaw4132
  • Fig. 1 Destabilization of the WAIS in the unperturbed reference simulation.

    (A) Grounding line and calving front of present-day observed state (green contours) and evolution of grounding line position during self-sustained retreat (colored contours, 750-year time steps), underlaid by bed topography (blue shading). The mass addition region used in the perturbation simulations is highlighted by the white sector, within which mass deposition is restricted to ice sheet areas that have been grounded at the onset of the perturbation. Insets show the state of the Antarctic Ice Sheet as observed (B) and after simulated collapse of the WAIS (C). Hatched area refers to the region outside the model domain, and blue rectangle indicates region shown in (A).

  • Fig. 2 Time series of ice loss from the Amundsen Sea sector for the cases of unperturbed destabilization (black) and mass deposition (colored).

    (A) Changes in sea level relevant ice volume. (B) Rate of ice loss. Colors of the curves indicate surplus (red) or lack (blue) in added mass with respect to stabilization threshold, Mc (see Fig. 4B). Shaded areas indicate the ranges of observed present-day rates of ice loss from the WAIS [purple, 66th percentile with median dashed; (2)] and the Amundsen Sea sector [gray; (1)]. Continuation of these trends into the future is illustrative, as the drivers of these trends are still disputed. SLE, sea level equivalent.

  • Fig. 3 Evolution of PIG and TG profiles in 250 year time steps.

    (A) The unperturbed reference simulation and (B and C) a mass addition of M = 8000 Gt for two different combinations of rate R and duration T of the perturbation. While the low-rate perturbation (B) cannot prevent ice sheet collapse, the high-rate perturbation (C) is sufficient to stabilize the ice sheet (see corresponding white stars in Fig. 4). The two vertical lines indicate the sections of mass addition (asterisks) along the transects. The ice shelf is truncated 25 km downstream of the grounding line for clarity. Locations of cross sections are shown in Fig. 1A.

  • Fig. 4 Stability diagrams of the WAIS.

    (A) Rate R versus duration T of mass addition with unstable regime in red and stable regime in blue. Interpolation of the field is based on the conducted ensemble of stabilization experiments (gray circles). The critical threshold Rc (white curve) of stabilization is approximated by function given at the top right corner. The approximated threshold is transferred into phase space of (B) total amount M versus duration of mass addition, and (C) total amount versus rate of mass addition. White stars highlight simulations that share the same total amount of deposited mass (M = 8000 Gt), added at differing rate and duration, showing that the combination of both determines potential stabilization.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/7/eaaw4132/DC1

    Fig. S1. Observed and modeled ice surface speed.

    Fig. S2. Cross sections through PIG and TG for a fixed perturbation duration (T = 20 years) and a varying rate R (increasing from top to bottom), corresponding to the column of black circles in Fig. 4A.

    Fig. S3. Cross sections through PIG and TG for a fixed perturbation rate (R = 250 Gt year−1) and a varying duration T (increasing from top to bottom), corresponding to the row of black circles in Fig. 4A.

    Reference (66)

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Observed and modeled ice surface speed.
    • Fig. S2. Cross sections through PIG and TG for a fixed perturbation duration (T = 20 years) and a varying rate R (increasing from top to bottom), corresponding to the column of black circles in Fig. 4A.
    • Fig. S3. Cross sections through PIG and TG for a fixed perturbation rate (R = 250 Gt yr−1) and a varying duration T (increasing from top to bottom), corresponding to the row of black circles in Fig. 4A.
    • Reference (66)

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