Research ArticleCLIMATOLOGY

Should coastal planners have concern over where land ice is melting?

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Science Advances  15 Nov 2017:
Vol. 3, no. 11, e1700537
DOI: 10.1126/sciadv.1700537
  • Fig. 1 Sensitivity of SLR to worldwide variations in ice thickness.

    (A) Gradient −dSNY/dH (in 10−3 μm/m per km2) of sea level in New York (SNY) with respect to ice thickness (H) changes in glaciated areas. The gradient units reflect a measure of SLR change (in μm) per unit of ice thickness change (in m) per area unit of ice (in km2), which is equivalent to SLR change (in mm) per unit change in ice mass (in GT). Signs rendered for dS/dH result in positive sensitivities of SLR to negative thickness changes (that is, shrinking ice sheets and glaciers resulting in positive GMSL rise). (B) GRACE-inferred ice thickness change (in cm/year) for Antarctica during January 2003–December 2015, demonstrating strong spatial variability. (C) Gradient −dSSydney/dH (in μm/m per km2) of sea level in Sydney (SSydney) with respect to ice thickness (H) changes in Antarctica. (D) LSL contribution −dSSydney/dHH (in μm/km2 per year) for each km2 area of Antarctica to LSL in Sydney. The sum of this quantity over the entire ice sheet quantifies the contribution of the entire AIS to LSL in Sydney. Coastlines are plotted in black.

  • Fig. 2 Sensitivity of SLR along U.S./Canadian coastlines to GrIS thickness variations.

    Gradient −dS/dH (in 10−3 μm/m per km2) at U.S. and Canadian coastal cities. Maps 1 to 9 correspond, respectively, to gradients computed for each of the named ports numbered clockwise from Halifax. −dS/dH is computed using the ISSM-AD (23) gradient solver. The forward SLR run used to support the derivation of –dS/dH is shown in the center Earth map (in mm/year). It is computed using the ISSM-SESAW (29) solver with model inputs (ice thickness change) inferred from GRACE for the period 2003–2016. This forward model therefore captures the response to thickness changes in all of the main glaciated areas of the world (including, among others, Alaskan and Canadian Arctic Glaciers, Himalayan Glaciers, Patagonia Glaciers, and the Greenland and Antarctica Ice Sheets) (28), hence representing a truly global “ice” fingerprint.

  • Fig. 3 GMSL ratios for select coastline cities across Europe applied to GrIS.

    GMSL ratios (in %) for coastal cities across Europe (from −100 to 100%). The ratios are defined as gradients of local SLR with respect to changes in ice thickness, −dS/dH, normalized by the equivalent GMSL gradient –dSGMSL/dH, where SGMSL is the GMSL signal induced by an equivalent change in ice thickness. These ratios measure the departure from GMSL contributed by local ice thickness changes in Greenland. They can be used to multiply against observed/predicted ice thickness changes to quantify any non-GMSL effects at any coastal city of the world.

  • Fig. 4 Projected contribution of GrIS to SLR in New York and London based on the SeaRISE experiments.

    Two hundred–year projection of the contribution (in μm/km2) of local areas in Greenland to SLR in New York (first column), London (second column), and any geographical location that experiences only the GMSL variation (third column) using two models of ice thickness change from the SeaRISE (15) experiments: Simulation Code for Polythermal Ice Sheets (SICOPOLIS) and University of Maine Ice Sheet Model (UMISM). The units reflect a measure of SLR change (in μm) per area unit (in km2) of the GrIS. It is equal to the gradient fingerprint multiplied by the GrIS thickness change, or dS/dH|localH, where dS/dH|local is the gradient fingerprint for the local port city and ΔH is the projected ice thickness change for the GrIS. This localized contribution can be summed up over the entire GrIS to compute SLR for London, for example, Embedded Image. For reference, we provide total SLR computed for London, New York, and the GMSL scenario. Note that in these two SeaRISE GrIS projections, both London and New York have LSL changes that are reduced over the GMSL rise that will affect far-field cities.

  • Table 1 Contribution of Greenland catchment basins to LSL.

    GFM-derived contribution of five catchment basins (Petermann Glacier, Helheim Glacier, North-East Greenland Ice Stream, and Jakobshavn Glacier, all delimited in fig. S1) to LSL in 30 cities around the world based on an average of two SeaRISE model runs (see Materials and Methods) over a 200-year time period. For each basin, the projected GMSL value is provided for reference. For each city, a value of LSL is provided in cm, along with a ratio to GMSL in %.

    CityPetermann Glacier: 8.22 cmHelheim Glacier: 1.4 cmNorth-East Greenland Ice Stream: 10.6 cmJakobshavn Glacier: 4.41 cm
    New York5.1 cm (62%)0.497 cm (36%)7.2 cm (68%)1.54 cm (35%)
    Miami7.51 cm (91%)1.09 cm (78%)10.1 cm (95%)3.41 cm (77%)
    Los Angeles7.44 cm (91%)1.35 cm (96%)10.6 cm (100%)4.04 cm (92%)
    Seattle5.42 cm (66%)1.13 cm (81%)8.67 cm (82%)3.23 cm (73%)
    Rio10.1 cm (123%)1.83 cm (131%)13.2 cm (124%)5.69 cm (129%)
    Ushuaia10.7 cm (130%)1.94 cm (139%)13.7 cm (129%)6.07 cm (138%)
    Lima9.57 cm (116%)1.66 cm (119%)12.3 cm (116%)5.2 cm (118%)
    Panama8.88 cm (108%)1.44 cm (103%)11.6 cm (109%)4.52 cm (102%)
    London3.38 cm (41%)−0.174 cm (−12%)1.7 cm (16%)0.257 cm (6%)
    Oslo1.38 cm (17%)−0.305 cm (−22%)−2.24 cm (−21%)−0.276 cm (−6%)
    Athens6.78 cm (83%)0.925 cm (66%)7.36 cm (69%3.18 cm (72%)
    Casablanca6.51 cm (79%)0.647 cm (46%)7.3 cm (69%)2.45 cm (55%)
    Luanda9.14 cm (111%)1.58 cm (113%)11.9 cm (112%)4.95 cm (112%)
    Durban9.77 cm (119%)1.76 cm (126%)13.1 cm (123%)5.41 cm (123%)
    Djibouti8.55 cm (104%)1.42 cm (102%)10.7 cm (100%)4.52 cm (103%)
    Alexandria7.42 cm (90%)1.11 cm (79%)8.51 cm (80%)3.67 cm (83%)
    Karachi8.56 cm (104%)1.48 cm (105%)10.5 cm (99%)4.69 cm (106%)
    Colombo9.63 cm (117%)1.66 cm (119%)12.3 cm (116%)5.22 cm (118%)
    Jakarta9.69 cm (118%)1.64 cm (118%)12.5 cm (118%)5.16 cm (117%)
    Brunei9.75 cm (119%)1.7 cm (122%)12.6 cm (118%)5.32 cm (121%)
    Sydney8.96 cm (109%)1.39 cm (99%)11.3 cm (106%)4.43 cm (100%)
    Perth8.9 cm (108%)1.42 cm (101%)11.5 cm (109%)4.47 cm (101%)
    Hong Kong9.64 cm (117%)1.76 cm (126%)12.4 cm (116%)5.5 cm (125%)
    Tokyo9.84 cm (120%)1.91 cm (136%)12.9 cm (122%)5.89 cm (133%)
    Okhotsk6.86 cm (83%)1.61 cm (115%)9.43 cm (89%)4.84 cm (110%)
    Karatayka1.71 cm (21%)0.638 cm (46%)−0.398 cm (−4%)2.02 cm (46%)
    Nordvik0.819 cm (10%)−0.621 cm (−44%)−3.34 cm (−31%)−1.04 cm (−24%)
    Reykjavik−4.85 cm (−59%)−5.23 cm (−373%)−12.8 cm (−121%)−10.2 cm (−231%)
    Ellesmere−94.7 cm (−1153%)−1.2 cm (−86%)−28.5 cm (−268%)−6.01 cm (−136%)
    Barrow0.31 cm (4%)0.95 cm (68%)3.57 cm (34%)2.48 cm (56%)

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/11/e1700537/DC1

    fig. S1. Greenland basins used in Table 1.

    fig. S2. Sensitivity of SLR along the South American coastline to GrIS thickness variations.

    fig. S3. Sensitivity of SLR along the European coastline to GrIS thickness variations.

    fig. S4. Sensitivity of SLR along the African coastline to GrIS thickness.

    fig. S5. Sensitivity of SLR along the Middle East and South Asian coastlines to GrIS thickness variations.

    fig. S6. Sensitivity of SLR along the Southeast Asian coastline to GrIS thickness variations.

    fig. S7. Sensitivity of SLR along the Australian coastline to GrIS thickness variations.

    fig. S8. Sensitivity of SLR along the East Asian coastline to GrIS thickness variations.

    fig. S9. Sensitivity of SLR along the Northeast Asian and the Russian Arctic coastlines to GrIS thickness variations.

    fig. S10. Sensitivity of SLR along the Canadian Arctic coastline to GrIS thickness variations.

    fig. S11. Sensitivity of SLR along the North American coastline to AIS thickness variations.

    fig. S12. Sensitivity of SLR along the South American coastline to AIS thickness variations.

    fig. S13. Sensitivity of SLR along the European coastline to AIS thickness variations.

    fig. S14. Sensitivity of SLR along the African coastline to AIS thickness variations.

    fig. S15. Sensitivity of SLR along the Middle East and Southeast Asian coastlines to AIS thickness variations.

    fig. S16. Sensitivity of SLR along the Southeast Asian coastline to AIS thickness variations.

    fig. S17. Sensitivity of SLR along the Australian coastline to AIS thickness variations.

    fig. S18. Sensitivity of SLR along the East Asian coastline to AIS thickness variations.

    fig. S19. Sensitivity of SLR along the Northeast Asian and the Russian Arctic coastlines to AIS thickness variations.

    fig. S20. Sensitivity of SLR along the Canadian Arctic coastline to AIS thickness variations.

    fig. S21. Sensitivity of SLR for 15 reliable tide gauges around the world to GrIS thickness variations.

    fig. S22. Sensitivity of SLR for 15 reliable tide gauges around the world to AIS thickness variations.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Greenland basins used in Table 1.
    • fig. S2. Sensitivity of SLR along the South American coastline to GrIS thickness variations.
    • fig. S3. Sensitivity of SLR along the European coastline to GrIS thickness variations.
    • fig. S4. Sensitivity of SLR along the African coastline to GrIS thickness.
    • fig. S5. Sensitivity of SLR along the Middle East and South Asian coastlines to GrIS thickness variations.
    • fig. S6. Sensitivity of SLR along the Southeast Asian coastline to GrIS thickness variations.
    • fig. S7. Sensitivity of SLR along the Australian coastline to GrIS thickness variations.
    • fig. S8. Sensitivity of SLR along the East Asian coastline to GrIS thickness variations.
    • fig. S9. Sensitivity of SLR along the Northeast Asian and the Russian Arctic coastlines to GrIS thickness variations.
    • fig. S10. Sensitivity of SLR along the Canadian Arctic coastline to GrIS thickness variations.
    • fig. S11. Sensitivity of SLR along the North American coastline to AIS thickness variations.
    • fig. S12. Sensitivity of SLR along the South American coastline to AIS thickness variations.
    • fig. S13. Sensitivity of SLR along the European coastline to AIS thickness variations.
    • fig. S14. Sensitivity of SLR along the African coastline to AIS thickness variations.
    • fig. S15. Sensitivity of SLR along the Middle East and Southeast Asian coastlines to AIS thickness variations.
    • fig. S16. Sensitivity of SLR along the Southeast Asian coastline to AIS thickness variations.
    • fig. S17. Sensitivity of SLR along the Australian coastline to AIS thickness variations.
    • fig. S18. Sensitivity of SLR along the East Asian coastline to AIS thickness variations.
    • fig. S19. Sensitivity of SLR along the Northeast Asian and the Russian Arctic coastlines to AIS thickness variations.
    • fig. S20. Sensitivity of SLR along the Canadian Arctic coastline to AIS thickness variations.
    • fig. S21. Sensitivity of SLR for 15 reliable tide gauges around the world to GrIS thickness variations.
    • fig. S22. Sensitivity of SLR for 15 reliable tide gauges around the world to AIS thickness variations.

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