Antarctic and Deep Pacific Temperature Changes Lead Tropical Pacific SSTs During Rapid Climate Change

The role that tropical Pacific ocean/atmospheric variability has had in abrupt climatic changes throughout the Quaternary continues to be debated. The debate centers in part, on how representative modern ocean/atmospheric variability in the tropical Pacific is for characterizing past variability, particularly protracted climatic changes such as the Dansgaard/Oeschger climatic events and even the glacial terminations. Among the strategies needed to assess a tropical Pacific influence on these longer time scales is a robust estimate of the phasing of tropical vs extratropical climate change. This is a difficult challenge to address with paleo- archives such as marine sediment cores because our ability to quantify timing and rates of change from these archives can be as large as or larger than the phasing timescale itself. In the case of the last glacial termination we present a new look at old proxy data from marine cores in the tropical Pacific in an attempt to place in temporal relationship the relative timing of high vs low latitude climatic warming. We show that deep sea temperatures within the Pacific that are indicative of circum-Antarctic climate began to warm in advance of the tropical surface ocean by approximately 1000 years. Deep waters between 1000 and 3500 meters appear to have warmed by 2oC between 19 and 14.6 kyBP and therefore, well ahead of the meltwater pulse 1A. In fact, it appears that virtually all of the deglacial warming in the deep Pacific Ocean occurred before the major onset of deglaciation in the northern hemisphere. Consequently, from a southern hemisphere perspective, much of the warming associated with the glacial termination was not associated with the rise in atmospheric CO2 concentrations. We further show that a similar lead-lag relationship existed between tropical SSTs and Pacific Deep Water temperatures during the abrupt climatic changes in Marine Stage III. It appears therefore that there has been a persistent and recurrent pattern of southern-first, tropics-next during periods of large abrupt climatic change.