FIGURE 2.1 Schematic of the major warm (red to yellow) and cold (blue to purple) water pathways in the North Atlantic subpolar gyre. Acronyms not in the text: Denmark Strait (DS); Faroe Bank Channel (FBC); East and West Greenland Currents (EGC, WGC); North Atlantic Current (NAC); DSO (Denmark Straits Overflow); ISO (Iceland-Scotland Overflow). Figure courtesy of H. Furey (WHOI).

abruptly changed in the past. Following on this examination, questions have arisen as to the possible likelihood of an abrupt change in the future.

The Stability of the Atlantic Meridional Overturning Circulation

Climate and Earth system models are used to understand potential changes in the AMOC, including potential feedbacks in the system, although the representation of unresolved physics (such as the parameterization of ocean mixing) could potentially be of concern in long, centennial simulations. Because saltier water is denser and thus more likely to sink, the transport of salt poleward into the North Atlantic provides a potentially destabilizing advective feedback to the AMOC (Stommel, 1961); i.e., a reduction in the strength of the AMOC would lead to less salt being transported into the North Atlantic, and hence a further reduction in the AMOC would ensue. As noted

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