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Future Response of Sea Ice

The CCCma first and second generation global coupled model (CGCM1, CGCM2) have been used to produce climate simulations from 1900 to the present and projections from the present to several centuries into the future. The projections are based on a prescribed evolution of greenhouse gas and aerosol forcing. More details regarding this model and the experiments are available on the CCCma website .

prediction of huge drop in sea ice extent by 2100

Figure 1: CCCma prediction of sea ice extent during the 21st century.

Figure 1 shows the sea ice extent for the Northern Hemisphere starting in 1900 to 2100. Sea ice extent begins to decrease around the time of the sea ice chart observational record from 1968 to 1999. The decrease is close to the observed decrease of 3% per decade seen in the observational record. Ice extent starts to decrease slightly more rapidly after 2000. By about 2050, summer sea ice cover over the Arctic Ocean has disappeared.

Note that these results are obtained from one particular model using one particular scenario for future greenhouse gas and aerosol forcing. They are provided here as an example of projected changes in the cryosphere which might accompany changing climate. More figures: - Note: Color bar indicates ice thickness in meters.

seaice_1980

Figure 1: Arctic sea-ice thickness (m) obtained from the CCCma Coupled Global Climate Model for March, averaged over years 1971-1990.


seaice_2050

Figure 2: Arctic sea-ice thickness (m) obtained from the CCCma Coupled Global Climate Model for March, averaged over years 2041-2060.


seaice_2090

Figure 3: Arctic sea-ice thickness (m) obtained from the CCCma Coupled Global Climate Model for March, averaged over years 2081-2100.


The oceanic and sea-ice components of GCMII are highly simplified. An ocean mixed-layer model is used together with an embedded thermodynamic sea-ice model. The oceanic component is simply a 50 m thick slab of quiescent seawater. Ice is allowed to form at the top of the water slab when it cools down to the freezing point of seawater.