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Sea ice evolution over the 20th and 21st centuries as simulated by current AOGCMs

Summary: Sea ice evolution over the 20th and 21st centuries
as simulated by current AOGCMs
Olivier Arzel *, Thierry Fichefet, Hugues Goosse
Institut d'Astronomie et de Ge´ophysique Georges Lemai^tre, Universite´ catholique de Louvain,
Chemin du cyclotron, 2, 1348 Louvain-la-Neuve, Belgium
Received 6 May 2005; received in revised form 8 July 2005; accepted 9 August 2005
Available online 8 September 2005
Outputs from simulations performed with current atmosphere-ocean general circulation models for the Fourth Assess-
ment Report of Intergovernmental Panel on Climate Change (IPCC AR4) are used to investigate the evolution of sea ice
over the 20th and 21st centuries. We first use the results from the ``Climate of the 20th Century Experiment'' to assess the
ability of these models to reproduce the observed sea ice cover changes over the periods 1981­2000 and 1951­2000. The
projected sea ice changes over the 21st century in response to the IPCC Special Report on Emission Scenarios A1B are then
examined. Overall, there is a large uncertainty in simulating the present-day sea ice coverage and thickness and in predict-
ing sea ice changes in both hemispheres. Over the period 1981­2000, we find that the multimodel average sea ice extent
agrees reasonably well with observations in both hemipsheres despite the wide differences between the models. The largest
uncertainties appear in the Southern Hemisphere. The climate change projections over the 21st century reveal that the
annual mean sea ice extent decreases at similar rates in both hemispheres, and that the reduction in annual mean sea
ice volume is about twice that of sea ice extent reduction in the Northern Hemisphere, in agreement with earlier studies.
We show that the amplitude of the seasonal cycle of sea ice extent increases in both hemispheres in a warming climate, with


Source: Arzel, Olivier - Climate Change Research Centre, University of New South Wales


Collections: Geosciences