Ocean heat transport during the Last Glacial Maximum

The annual mean oceanic poleward heat transport during the last ice age is calculated using surface heat fluxes from a global atmospheric general circulation model. The atmospheric model is used to simulate the climate 18,000 years ago using Climate: Long‐Rang Investigation, Mapping and Prediction data for the model's seasonally varying sea surface temperature and ice cover. Heat transport is obtained by assuming that there is no net heat storage in the ocean over an annual cycle and by calculating the required converged ocean heat transport for each latitude band. Ocean heat transports for the present‐day climate have been calculated with this model and are in good agreement with other studies. The results indicate that the global transports are similar for the present climate and the ice age except for the northern high latitudes where the present climate has significant poleward transport. The maximum transports occur at the same latitudes in both cases, are about the same magnitude in the northern hemisphere, and are somewhat larger during the ice age in the southern hemisphere. The maximum northward transport in the North Pacific is about twice as large for the ice age as for the present climate. For the present climate in the Atlantic there is a net northward transport of heat at all latitudes and hence a net transport of heat into the Atlantic from other basins. For the ice age in the Atlantic there is a reduced northward transport in the northern hemisphere, a southward transport in the southern hemisphere, and a net transport of heat out of the Atlantic into the other ocean basins.