Analyses of the predicted changes of the global oceans under the increased greenhouse gases scenarios

Abstract

A new climate model (ECHAM5/MPI-OM1) developed for the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC) at Max-Planck Institute for Meteorology is used to study the climate changes under the different increased CO2 scenarios (B1, A1B and A2). Based on the corresponding model results, the sea surface temperature and salinity structure, the variations of the thermohaline circulation (THC) and the changes of sea ice in the northern hemisphere are analyzed. It is concluded that from the year of 2000 to 2100, under the B1, A1B and A2 scenarios, the global mean sea surface temperatures (SST) would increase by 2.5°C, 3.5°C and 4.0°C respectively, especially in the region of the Arctic, the increase of SST would be even above 10.0°C; the maximal negative value of the variation of the fresh water flux is located in the subtropical oceans, while the precipitation in the eastern tropical Pacific increases. The strength of THC decreases under the B1, A1B and A2 scenarios, and the reductions would be about 20%, 25% and 25.1% of the present THC strength respectively. In the northern hemisphere, the area of the sea ice cover would decrease by about 50% under the A1B scenario.