The effect of temperature change of the warm surface waters of the oceans on atmospheric CO₂

It is widely believed that the concentration of atmospheric CO 2 is largely controlled by the high‐latitude oceans, because these waters can be viewed as an outcropping of oceanic deep water. If this tenet is correct, cooling of the low‐latitude surface oceans could contribute only marginally to an explanation of the observed decrease in atmospheric CO 2 concentration of about 80 ppm during glacial periods. This tenet is examined with three‐dimensional ocean chemical models based on the circulation fields from 10‐level and 15‐level ocean general circulation models developed at the Max‐Planck‐Institut für Meteorologie, Germany. The three‐dimensional models predict atmospheric CO 2 changes that are much larger than those predicted by outcrop models, thereby casting doubt on the use of outcrop models to model atmospheric CO 2 changes. The atmospheric response time to a change in sea surface temperature is about 120 years in the 15‐level model, the more realistic of the two three‐dimensional models. This response is fast enough, and the predicted amplitude is of the right size, for one to explain the CO 2 increase associated with the Dansgaard‐Oeschger warming events observed in ice core measurements as the effect of a warming of the surface oceans.