The future of the AMOC under global warming and Greenland Ice Sheet melt: AMOCMIP and probabilistic projections.
Pepijn Bakker1, Andreas Schmittner2, Oleg Saenko3, Michiel R van den Broeke4, Jan Lenaerts5, Dave Bi6, Aixue Hu7, Rumi Ohgaito8, Ayako Abe-Ouchi9, Didier Swingedouw10, Simon James Marsland6, Sebastian H Mernild11, Jianjun Yin12 and Rebecca Lynn Beadling12, (1)Vrije Universiteit Amsterdam, Earth Sciences, Amsterdam, Netherlands, (2)Oregon State University, College of Earth, Ocean, and Atmospheric Sciences, Corvallis, OR, United States, (3)Canadian Centre for Climate Modelling and Analysis, Victoria, BC, Canada, (4)Utrecht University, Utrecht, Netherlands, (5)University of Colorado Boulder, Atmospheric and Oceanic Science, Boulder, CO, United States, (6)CSIRO, Aspendale, Australia, (7)National Center for Atmospheric Research, Boulder, CO, United States, (8)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (9)University of Tokyo, Atmosphere and Ocean Research Institute, Bunkyo-ku, Japan, (10)University of Bordeaux 1, Pessac, France, (11)Center for Scientific Studies, Glaciology and Climate Change Laboratory, Valdivia, Chile, (12)University of Arizona, Tucson, AZ, United States
Abstract:
The evolution of the Atlantic Meridional Overturning Circulation (AMOC) is one of the key uncertainties of future climate projections. The latest IPCC assessment, reported that under the intermediate Representative Concentration Pathway (RCP) 4.5 scenario the AMOC might reduce by 20-30% by the end of the century. For the high-end RCP8.5 scenario these number go up to reductions of 36-44% compared to the present-day AMOC strength. However, all of these projections neglect future increases in the melt rates of the Greenland Ice Sheet (GIS) and the potential impact on the AMOC evolution.
We present results of AMOCMIP, a community effort to use state-of-the-science climate models to simulate the impact of partial melt of the GIS and future global warming on the strength of the AMOC. Realistic scenarios of the mass loss of the GIS for the next three centuries are constructed for different RCPs by combining observations and regional climate model experiments. These GIS melt and RCP scenarios are used to force the state-of-the-science climate models that are taking part in the AMOCMIP.
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 estimate the impact of a large number of uncertainties in AMOC projections: future greenhouse-gas emissions, the AMOC's sensitivity to temperature and salinity changes, future global and regional warming and melt rates of the GIS. Based on all currently available AMOCMIP simulations, we will present probabilistic projections of future AMOC changes and the probability of an AMOC collapse.
