Atlantic heat uptake and redistribution as a response to air-sea heat flux perturbations

More than 90% of the energy due to global warming since 1971 has been taken up by the ocean. The rate of increase of global mean surface temperature is thus sensitive to the rate of ocean heat uptake. It is difficult to determine the regional pattern of heat uptake and its change as a function of surface fluxes, with climate models showing considerable diversity in future heat uptake patterns. These patterns are important for sea level rise and forcing atmospheric dynamics, as well as heat uptake efficiency. We are using a low-resolution ocean model (MITgcm) to emulate CMIP5 models and perturb the net air-sea flux to establish physical understanding of how patterns of air-sea flux perturbations lead to patterns of ocean heat uptake. We find that high-latitude North Atlantic and Southern Ocean forcing dominates the global heat uptake pattern. The use of a suite of passive tracers allows us to split the warming signal into an added heat response and a change in ocean heat transport convergence. While the added heat signal is strong in the North Atlantic, on decadal timescales other basins are affected through the redistribution of existing heat by a changing circulation.