AMOCMIP: Probabilistic projections of future AMOC evolution driven by global warming and Greenland Ice Sheet melt.

Thursday, 17 December 2015: 12:05
2012 (Moscone West)
Pepijn Bakker1, Rumi Ohgaito2, Ayako Abe-Ouchi3, Didier Swingedouw4, Oleg Saenko5, Simon James Marsland6, Dave Bi6, Andreas Schmittner1, Aixue Hu7, Sebastian H Mernild8, Jianjun Yin9, Rebecca Lynn Beadling9, Jan Lenaerts10 and Michiel van den Broeke11, (1)Oregon State University, College of Earth, Ocean, and Atmospheric Sciences, Corvallis, OR, United States, (2)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (3)University of Tokyo, Bunkyo-ku, Japan, (4)University of Bordeaux 1, Pessac, France, (5)Environment Canada Toronto, Toronto, ON, Canada, (6)CSIRO, Aspendale, Australia, (7)National Center for Atmospheric Research, Boulder, CO, United States, (8)Center for Scientific Studies, Glaciology and Climate Change Laboratory, Valdivia, Chile, (9)University of Arizona, Tucson, AZ, United States, (10)Utrecht University, Utrecht, Netherlands, (11)University of Oregon, Eugene, OR, United States
We present results of a community effort to use state-of-the-science climate models to simulate the impact of the partial melt of the Greenland Ice Sheet on the Atlantic Meridional Overturning Circulation (AMOC) under future global warming: the AMOC Model Intercomparison Project (AMOCMIP). The evolution of the AMOC is one of the key uncertainties of future climate projections. Climate models taking part in CMIP5 showed that over the 21st century the AMOC might reduce by 20-30% under the intermediate Representative Concentration Pathways (RCP) 4.5 scenario and by 36-44% under the high-end RCP8.5 scenario relative to preindustrial values. However, these projections didn't include the predicted partial melting of the Greenland Ice Sheet. Using a combination of observations and regional climate model experiments, realistic scenarios of the future mass loss of the Greenland Ice Sheet are constructed for different RCPs that span the next three centuries. These melt water scenarios have been included in various climate models to investigate its role in the simulated future evolution of the climate in general and more specifically the AMOC. To rigorously quantify the uncertainties of the AMOC projections and the probability of a future AMOC collapse we have used an AMOC emulator. This physics-based approach allows us to include uncertainties in the AMOC's sensitivity to temperature and salinity changes, as well as uncertainties of future global warming, polar amplification and melt rates of the Greenland Ice Sheet. Based on the first AMOCMIP simulations of future AMOC evolution forced by changes in greenhouse-gas concentrations and Greenland Ice Sheet melt, we will present probabilistic projections of future AMOC changes and the probability of an AMOC collapse.