Loosening the AMOC's Grip on the Atlantic Climate (Invited Presentation)

The Atlantic Meridional Overturning Circulation (AMOC) is widely invoked to explain variability of the North Atlantic climate, and there is even a broad public understanding that the strength of the “conveyor belt” impacts our global climate. The linkage between the AMOC and North Atlantic SST, has generally been described as follows: Changes in surface heat fluxes and/or freshwater input in the high latitude North Atlantic Ocean dictate the amount of deep water formed, which is exported equatorward to the subtropical basin and, eventually to distant parts of the globe. This export of deep water causes coherent AMOC changes throughout the North Atlantic basin. An increased AMOC brings more heat across the equator, warming the surface waters of the North Atlantic. These ocean-driven changes warm the overlying atmosphere and, consequentially produce impacts over the land around the Atlantic basin and beyond.

However, several recent studies based on oceanographic and atmospheric observations and climate models, raise questions as to the suitability of this AMOC-climate paradigm for explaining modern multi-decadal variability in the Atlantic. The aim of this paper is to place those questions in a common framework by critically examining the many-layered assumptions in the AMOC-climate paradigm. We conclude that adherence to this paradigm may limit progress on understanding the causes of modern upper ocean heat content anomalies and the associated worldwide climate phenomena. We will propose some alternative views of Atlantic climate variability.