Effect of Resolving Ocean Eddies on the Transient Response of Global Mean Surface Temperature to Abrupt 4xCO2 Forcing

Abstract

The magnitude of global mean surface temperature (GMST) response to increasing atmospheric CO2 concentrations is affected by the efficiency of ocean heat uptake, which in turn can be affected by oceanic mesoscale eddies. Using the Max Planck Institute - Earth System Model (MPI-ESM1.2), we find that resolving eddies leads to a −0.1°C cooler response of GMST to an abrupt CO2 quadrupling, which is related to a larger rate of heat uptake by an eddying ocean. This is consistent with changes in the energy budget of the whole climate system induced by increasing ocean resolution under the same radiative forcing and climate feedback. As a fast response, heat is taken up by the deep ocean, independent of resolution. The change in deep ocean heat uptake due to resolved eddies is an amplification in the magnitude of the responses of all heat processes, including eddy heat advection, mean heat advection, and diffusive processes.