Arctic freshwater export in the 20th and 21st centuries

Climate simulations suggest that the emissions of carbon dioxide and other greenhouse gases will lead to strong climate changes in the 21st century. Here the resulting effects of the freshwater balance of the Arctic Ocean in the 21st century are analyzed using coupled Intergovernmental Panel on Climate Change simulations with the Max Planck Institute for Meteorology climate model. For the Arctic region, particularly strong warming and an almost complete removal of sea ice during summer time are predicted. Arctic river runoff and net atmospheric freshwater input ( P-E) are strongly enhanced. Most of this additional freshwater input is stored in the Arctic Ocean. While the total freshwater export out of the Arctic remains almost constant, significant changes occur in its distribution. The dominance of sea ice for the Fram Strait export disappears, while the liquid freshwater export is enhanced. The mean export shows therefore almost no changes, but its interannual variability is slightly reduced. In contrast, both the export through the Canadian Archipelago and its variability are increased in the 21st century. Therefore the importance of the Canadian Archipelago for the total Arctic export grows. Enhanced freshwater input into the Labrador Sea leads to a strong decrease in deep convection. Greenland Sea convection is reduced as well but mainly because of strong warming of the upper ocean layers. The meridional overturning circulation responds with a decline of about 6 sverdrups.