Zhang, Bloch-Johnson, Romps, and Abbot, Evolving CO2 rather than SST leads to a factor of ten decrease in GCM convergence time, JAMES, 2021




An earlier paper applied an inverse climate-modeling method to rapidly equilibrate SST and CO2 in limited-area cloud-resolving simulations and proposed a way to extend that inverse method to global climate models. Here, that approach is tested in a global aquaplanet simulation of perpetual equinox and is found to accelerate the equilibration by a factor of ten.

This speedup enables the equilibration of 51 climate simulations to measure, in fine detail, the bump in equilibrium climate sensitivity that has been reported around a global mean temperature of 310-320 K. Other potential applications include the ability to probe unstable climate states and climate states close to bifurcations, such as the runaway greenhouse transition.

The "bump" in equilibrium climate sensitivity (ECS) probed with 51 equilibrated climate simulations, which were made possible by the rapid equilibration technique.