A new conceptual model of global ocean heat uptake

We formulate a new conceptual model, named “ MT 2”, to describe global ocean heat uptake, as simulated by atmosphere–ocean general circulation models (AOGCMs) forced by increasing atmospheric CO _2 , as a function of global-mean surface temperature change T and the strength of the Atlantic meridional overturning circulation (AMOC, M ). MT 2 has two routes whereby heat reaches the deep ocean. On the basis of circumstantial evidence, we hypothetically identify these routes as low- and high-latitude. In low latitudes, which dominate the global-mean energy balance, heat uptake is temperature-driven and described by the two-layer model, with global-mean T as the temperature change of the upper layer. In high latitudes, a proportion p (about 14