On the Climatic Impact of Ocean Circulation

Integrations of coupled climate models with mixed-layer and fixed-current ocean components are used to explore the climatic response to varying magnitudes of ocean circulation. Four mixed-layer ocean experiments without ocean heat transports are performed using two different atmosphere-land components-the new GFDL AM2 and the GFDL Manabe Climate Model (MCM)-and two different sea ice components, one dynamic and one thermodynamic. Both experiments employing the dynamic sea ice component develop unstable growth of sea ice while the experiments with a thermodynamic sea ice component develop very large but stable ice covers. The global cooling ranges from modest to extreme in the four experiments.