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Ice-dynamic projections of the Greenland ice sheet in response to atmospheric and oceanic warming

Tijdschriftbijdrage - Tijdschriftartikel

Continuing global warming will have a~strong impact on the Greenland ice sheet in the coming centuries. During the last decade (2000-2010), both increased surface melting and enhanced ice discharge from calving glaciers have contributed 0.6 ± 0.1 mm yr-1 to global sea-level rise, with a relative contribution of 60 and 40% respectively. Here we use a~higher-order ice flow model, spun up to present day, to simulate future ice volume changes driven by both atmospheric and oceanic temperature changes. For these projections, the flow model accounts for runoff-induced basal lubrication and ocean warming-induced discharge increase at the marine margins. For a suite of ten Atmosphere and Ocean General Circulation Models and four Representative Concentration Pathway scenarios, the projected sea-level rise between 2000 and 2100 lies in the range of +1.4 to +16.6 cm. For two low emission scenarios, the projections are conducted up to 2300. Ice loss rates are found to abate for the most favorable scenario where the warming already peaks in this century, which allows to preserve the ice sheet in a~geometry close to the present-day state. For the other moderate scenario, loss rates remain at a~constant level over three hundred years. The volume loss is predominantly caused by increased surface melting as the contribution from enhanced ice discharge decreases over time and is self-limited by thinning and retreat of the marine margin, reducing the ice-ocean contact area. As confirmed by other studies, the effect of enhanced basal lubrication on the volume evolution is found to be negligible on centennial time scales. The presented projections show that the observed rates of volume change over the last decades cannot simply be extrapolated over the 21st century on account of a different balance of processes causing ice loss over time. The results also indicate that the largest source of uncertainty arises from the surface mass balance and the underlying climate change projections, and not from ice dynamics.
Tijdschrift: Cryosphere
ISSN: 1994-0416
Issue: 3
Volume: 9
Pagina's: 1039-1062
Jaar van publicatie:2015
Trefwoorden:Greenland ice sheet, Climate warming, Modeling, Sea level change
CSS-citation score:3
Toegankelijkheid:Open