University of Luton, United Kingdom

An important factor in the Earth's heat budget is the production of cold, deep waters in the Southern Ocean. The deep western boundary current east of New Zealand dominates the supply of deep water to the Pacific Ocean. This paper attempts to reconstruct deep-water properties and speed changes during the Pleistocene using sediment records deposited under the influence of this deep western boundary current. Evidence for intensified deep Pacific Ocean inflow and ventilation during the glacial periods of the past 1.2 million years is found in physical and isotope records. An increased production of Antarctic Bottom Water during glacial times may be related to the changes in throughflow and can be caused by increasing wind strengths in the Southern Ocean or an increase in annual sea-ice formation. Global thermohaline circulation was inferred to be perturbed significantly during the mid-Pleistocene climate transition between 0.86 and 0.45 million years ago. (Mod. auth. abstr.)