Antarctic ice sheet - climate feedbacks under high future carbon\n emissions

Freshwater forcing from a retreating Antarctic Ice Sheet could have a wide\nrange of impacts on future global climate. Here, we report on multi-century\n(present-2250) climate simulations performed using a fully coupled numerical\nmodel integrated under future greenhouse gas emissions scenarios IPCC RCP4.5\nand 8.5, with meltwater discharge provided by a dynamic-thermodynamic ice sheet\nmodel. Accounting for Antarctica's meltwater contribution raises sub-surface\nocean temperatures by 1 C at the ice margin, beyond rates currently projected.\nIn contrast, 2-10 C cooler surface air and ocean temperatures in the Southern\nOcean cause sea ice to expand and delay the increase of projected global mean\nanthropogenic warming. In addition, the projected loss of Arctic winter sea ice\nand weakening of the Atlantic Meridional Overturning Circulation are delayed be\nseveral decades. Our results demonstrate a clear need to more accurately\naccount for meltwater input from ice sheets if we are to make confident climate\npredictions.\n