Glacial to interglacial changes in atmospheric carbon dioxide: the critical role of ocean surface water in high latitudes.

We follow up here on a proposal by Sarmiento and Toggweiler that glacial to interglacial changes in P_CO2 are related to changes in the nutrient content of high-latitude surface water. We develop a 4-box model of the ocean and atmosphere which includes low- and high-latitude surface boxes, an atmosphere, and a deep ocean. We propose that the low ice age P_CO2 can be produced by a reduction in local exchange between high-latitude surface water and deep water. The model requires that the current exchange rate of about 50Sv be reduced to about 10Sv. We review evidence in the geologic record for widespread changes in deep convection around Antarctica about 14 000yr ago which are synchronous with the change in atmospheric P_CO2.-from Authors