The stability and variability of AMOC and its impacts on regional and global climate

The Atlantic Meridional Overturning Circulation (AMOC) is a global-scale ocean circulation. It transports upper-ocean warm and salty water into the subpolar North Atlantic where this water loses heat to the overlying atmosphere, becomes dense, sinks to depth, flows southward, and upwells elsewhere of the world ocean. This circulation is important because of its multi-equilibrium states based on theoretical studies. Large variability in this circulation can also modulate the regional and global climate. Here, we study its stability, variability, and impacts on regional and global climates on various timescales using multi-versions of CCSM/CESM. We found that the bistability of AMOC depends on the background mean states and the nature of the forcing changes. Different changes in AMOC in response to the greenhouse gas forcing can affect how the surface climate would respond to this forcing change.