Multi-centennial evolution of the climate response and deep ocean heat uptake in a set of abrupt stabilization scenarios

A set of 1000-year long abrupt stabilization simulations have been performed with the EC-Earth3 climate model. Each simulation follows a sudden stabilization of the external forcing, starting at different years of the CMIP6 historical and SSP5-8.5 scenario. The final global mean temperature increases range between 1.4 and 9.6 K with respect to the pre-industrial baseline.

We first explore here the evolution of the climate response at multi-centennial timescales and its dependence on the level of forcing, with regards to the climate feedback parameter and to patterns of surface warming. We then focus on the rate of heat storage in the global ocean, which is the main driver of the climate response at multi-centennial timescales. We find that the rate of warming of the deep ocean is almost independent from the amplitude of the forcing, so that most of the additional heat remains in the upper layers at high forcing. We hypothesize that this is due - at least partly - to a decreased ventilation of the deep ocean, caused by a general reorganization of the Meridional Overturning Circulation (MOC).