Elimination of the Greenland ice sheet in a high-CO2 climate

Projections of future global sea level depend on reliable estimates of changes in the size of polar ice sheets. Calculating this directly from global general circulation models (GCMs) is unreliable because the coarse resolution of 100 km or more is unable to capture narrow ablation zones, and ice dynamics is not usually taken into account in GCMs. To overcome these problems a high-resolution (20 km) dynamic ice sheet model has been coupled to the third Hadley Centre Coupled Ocean–Atmosphere GCM (HadCM3). A novel feature is the use of two-way coupling, so that climate changes in the GCM drive ice mass changes in the ice sheet model that, in turn, can alter the future climate through changes in orography, surface albedo, and freshwater input to the model ocean. At the start of the main experiment the atmospheric carbon dioxide concentration was increased to 4 times the preindustrial level and held constant for 3000 yr. By the end of this period the Greenland ice sheet is almost completely ablated and has made a direct contribution of approximatel y7mt oglobal average sea level, causing a peak rate of sea level rise of 5 mm yr 1 early in the simulation. The effect of ice sheet depletion on global and regional climate has been examined and it was found that apart from the sea level rise, the long-term effect on global climate is small. However, there are some significant regional climate changes that appear to have reduced the rate at which the ice sheet ablates.

[1]  Jason E. Box,et al.  Greenland ice sheet surface mass balance 1991–2000: Application of Polar MM5 mesoscale model and in situ data , 2004 .

[2]  Daniel J. Lunt,et al.  Effects of a melted greenland ice sheet on climate, vegetation, and the cryosphere , 2004 .

[3]  Jonathan M. Gregory,et al.  A new method for diagnosing radiative forcing and climate sensitivity , 2004 .

[4]  D. Bromwich,et al.  Greenland ice sheet surface mass balance 1991 – 2000 : Application of Polar MM 5 mesoscale model and in situ data , 2004 .

[5]  Hugues Goosse,et al.  Implications of changes in freshwater flux from the Greenland ice sheet for the climate of the 21st century , 2003 .

[6]  M. Holland,et al.  Polar amplification of climate change in coupled models , 2003 .

[7]  Jonathan M. Gregory,et al.  Freshwater transports in HadCM3 , 2003 .

[8]  J. Christensen,et al.  Net accumulation of the Greenland ice sheet: High resolution modeling of climate changes , 2003 .

[9]  J. Gregory,et al.  Climatic Impact of a Greenland Deglaciation and Its Possible Irreversibility , 2003 .

[10]  A. Ohmura,et al.  Effects of polar ice sheets on global sea level in high‐resolution greenhouse scenarios , 2003 .

[11]  T. Mote.  Estimation of runoff rates, mass balance, and elevation changes on the Greenland ice sheet from passive microwave observations , 2003 .

[12]  P. Valdes,et al.  Atmospheric contributions to the surface mass balance of Greenland in the HadAM3 atmospheric model , 2002 .

[13]  C. Schwierz,et al.  CYCLONE TRACKS IN THE VICINITY OF GREENLAND – ASPECTS OF AN INTERACTION PROCESS , 2002 .

[14]  T. Mote,et al.  Surface mass balance of the Greenland ice sheet from climate-analysis data and accumulation/runoff models , 2002, Annals of Glaciology.

[15]  T. Fichefet,et al.  The response of the Greenland ice sheet to climate changes in the 21st century by interactive coupling of an AOGCM with a thermomechanical ice-sheet model , 2002, Annals of Glaciology.

[16]  J. van Ypersele,et al.  Modelling of large-scale melt parameters with a regional climate model in south Greenland during the 1991 melt season , 2002, Annals of Glaciology.

[17]  Philippe Huybrechts,et al.  Sea-level changes at the LGM from ice-dynamic reconstructions of the Greenland and Antarctic ice sheets during the glacial cycles , 2002 .

[18]  J. Houghton,et al.  Climate change 2001 : the scientific basis , 2001 .

[19]  M. Collins,et al.  Projections of future climate change , 2002 .

[20]  Curt H. Davis,et al.  Mass balance of higher-elevation parts of the Greenland ice sheet , 2001 .

[21]  Konrad Steffen,et al.  Surface climatology of the Greenland Ice Sheet: Greenland Climate Network 1995–1999 , 2001 .

[22]  P. deMenocal,et al.  Effects of glacial meltwater in the GISS coupled atmosphereocean model: 1. North Atlantic Deep Water response , 2001 .

[23]  P. deMenocal,et al.  Effects of glacial meltwater in the GISS coupled atmosphere-ocean model 2 , 2001 .

[24]  Niels Reeh,et al.  Thinning of the ice sheet in northwest Greenland over the past forty years , 2001, Nature.

[25]  Jonathan M. Gregory,et al.  Mechanisms Determining the Atlantic Thermohaline Circulation Response to Greenhouse Gas Forcing in a Non-Flux-Adjusted Coupled Climate Model , 2001 .

[26]  S. Marshall,et al.  Glacial termination: sensitivity to orbital and CO2 forcing in a coupled climate system model , 2001 .

[27]  Duncan J. Wingham,et al.  Changes in Sea Level , 2001 .

[28]  W. Krabill,et al.  Greenland Ice Sheet: High-Elevation Balance and Peripheral Thinning. , 2000, Science.

[29]  S. Marshall,et al.  Substantial contribution to sea-level rise during the last interglacial from the Greenland ice sheet , 2000, Nature.

[30]  John F. B. Mitchell,et al.  The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments , 2000 .

[31]  V. Pope,et al.  The impact of new physical parametrizations in the Hadley Centre climate model: HadAM3 , 2000 .

[32]  Philippe Huybrechts,et al.  The treatment of meltwater retention in mass-balance parameterizations of the Greenland ice sheet , 2000, Annals of Glaciology.

[33]  Shawn J. Marshall,et al.  Results from the EISMINT model intercomparison: the effects of thermomechanical coupling , 2000 .

[34]  Ralf Greve,et al.  On the Response of the Greenland Ice Sheet to Greenhouse Climate Change , 2000 .

[35]  Philippe Huybrechts,et al.  The Dynamic Response of the Greenland and Antarctic Ice Sheets to Multiple-Century Climatic Warming , 1999 .

[36]  R. Betts,et al.  The impact of new land surface physics on the GCM simulation of climate and climate sensitivity , 1999 .

[37]  E. Mosley‐Thompson,et al.  Annual accumulation at two sites in northwest Greenland during recent centuries , 1998 .

[38]  A. Weaver,et al.  Simulated influence of carbon dioxide, orbital forcing and ice sheets on the climate of the Last Glacial Maximum , 1998, Nature.

[39]  T. Stocker,et al.  The North Atlantic Oscillation and its imprint on precipitation and ice accumulation in Greenland , 1998 .

[40]  David P. Stevens,et al.  Prediction of iceberg trajectories for the North Atlantic and Arctic oceans , 1996 .

[41]  S. Rahmstorf.  Bifurcations of the Atlantic thermohaline circulation in response to changes in the hydrological cycle , 1995, Nature.

[42]  S. Baum,et al.  Is the Greenland Ice Sheet bistable , 1995 .

[43]  M. Loutre.  Greenland Ice Sheet over the next 5000 years , 1995 .

[44]  E. Morris,et al.  The response of large ice sheets to climatic change , 1992 .

[45]  I. Held,et al.  The Stationary Response to Large-Scale Orography in a General Circulation Model and a Linear Model , 1992 .

[46]  N. Reeh,et al.  The Greenland ice sheet through the last glacial-interglacial cycle , 1991 .

[47]  H. Stommel,et al.  Thermohaline Convection with Two Stable Regimes of Flow , 1961 .