Deep water formation and Quaternary glaciations

A large fraction of climatic varability on the Quaternary time scale can be explained by nonlinear interactions between the radiation balance of the global atmosphere-ocean system and the mass balance of Northern Hemisphere ice sheets. Recent analyses of paleoclimatic proxy data indicate a further important contribution to this variability from changes in deep-water formation occurring in the North Atlantic Subpolar Sea. We study the effects of these changes on variations in global temperature and ice volume characteristic of the late Quaternary. The novel framework of Boolean delay equations (BDEs) is used to formulate a conceptual model of the climatic system under study, and to analyze this formal model. Selfsustained oscillations in the intensity of the Atlantic Ocean's thermohaline circulation result from the interaction of sea-ice formation with the waxing and waning of continental ice sheets. The comparison of model results with paleoclimatic records suggests a considerable slowing down of the abyssal circulation during glacial episodes.