Journal Article

Elimination of the Greenland Ice Sheet in a High CO₂ Climate

Ridley, J. K., Gregory, J. M., Lowe, J. A., Huybrechts, P.

2005

Overview

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 approximately 7 m to global average sea level, causing a peak rate of sea level rise of 5 mm yr−1early 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.

• Publisher: American Meteorological Society
• Subject: 21st century / Ablation / Albedo / Atmosphere / Atmospheric circulation / Atmospheric models / Carbon dioxide / Carbon dioxide concentration / Climate / Climate change / Climate models / Climatology. Bioclimatology. Climate change / Earth, ocean, space / Exact sciences and technology / External geophysics / Fresh water / Freshwater / Future climates / General circulation models / Glaciation / Global climate / Global sea level / Greenland ice sheet / Ice / Ice effects / Ice sheet models / Ice sheets / Inland water environment / Marine / Meteorology / Modelling / Ocean circulation / Ocean-atmosphere interaction / Oceans / Orography / Precipitation / Regional climates / Resolution / Runoff / Sea level / Sea level changes / Sea level rise / Sea level rise effects / Sheet modelling / Simulation / Snow / Snow. Ice. Glaciers / Surface temperature / Temperature