Journal Article

Future sea-level rise from Greenland’s main outlet glaciers in a warming climate

Vieli, Andreas, Andersen, Morten Langer, Nick, Faezeh M., Edwards, Tamsin L., Payne, Antony, Pattyn, Frank, Joughin, Ian, van de Wal, Roderik S. W.

2013

Overview

A model of the four main outlet glaciers that drain the Greenland Ice Sheet predicts that they will contribute 19 to 30 millimetres to sea-level rise by 2200 in a mid-range future warming scenario, and 29 to 49 millimetres in a more extreme scenario. Greenland's role in sea-level rise revisited Recent dramatic acceleration of ice loss from the Greenland Ice Sheet has raised concerns about the possibility of runaway ice loss and consequent sea-level rise. Now Faezeh Nick and colleagues simulate the dynamics of ice movement for four of Greenland's largest outlet glaciers to 2200 using a model that takes account of the complicated dynamics that operate at the ice–ocean interface, such as calving and submarine melting. They find that in spite of several bursts of retreat, the current rate of acceleration of ice loss is unlikely to continue. This suggests that the contribution of the Greenland Ice Sheet to sea-level rise is likely to be considerably less than the upper limit of previous estimates. Over the past decade, ice loss from the Greenland Ice Sheet increased as a result of both increased surface melting and ice discharge to the ocean 1 , 2 . The latter is controlled by the acceleration of ice flow and subsequent thinning of fast-flowing marine-terminating outlet glaciers 3 . Quantifying the future dynamic contribution of such glaciers to sea-level rise (SLR) remains a major challenge because outlet glacier dynamics are poorly understood 4 . Here we present a glacier flow model that includes a fully dynamic treatment of marine termini. We use this model to simulate behaviour of four major marine-terminating outlet glaciers, which collectively drain about 22 per cent of the Greenland Ice Sheet. Using atmospheric and oceanic forcing from a mid-range future warming scenario that predicts warming by 2.8 degrees Celsius by 2100, we project a contribution of 19 to 30 millimetres to SLR from these glaciers by 2200. This contribution is largely (80 per cent) dynamic in origin and is caused by several episodic retreats past overdeepenings in outlet glacier troughs. After initial increases, however, dynamic losses from these four outlets remain relatively constant and contribute to SLR individually at rates of about 0.01 to 0.06 millimetres per year. These rates correspond to ice fluxes that are less than twice those of the late 1990s, well below previous upper bounds 5 . For a more extreme future warming scenario (warming by 4.5 degrees Celsius by 2100), the projected losses increase by more than 50 per cent, producing a cumulative SLR of 29 to 49 millimetres by 2200.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 704/106/125 / Altitude / Analysis / Climate / Climate change / Earth, ocean, space / Environmental aspects / Exact sciences and technology / External geophysics / Forecasts and trends / Freezing / Glaciers / Global warming / Global Warming - statistics & numerical data / Greenland / Humanities and Social Sciences / Ice / Ice Cover / letter / Models, Theoretical / multidisciplinary / Oceans and Seas / Physics of the oceans / Science / Sea level / Seawater - analysis / Snow. Ice. Glaciers / Studies / Surface waves, tides and sea level. Seiches / Surface-ice melting / Temperature