PACIFIC PERSPECTIVES ON THE YOUNGER DRYAS COOLING EVENT

The Younger Dryas cold reversal (YD) has been the subject of much scientific inquiry, as it is an interval when the Northern hemisphere climate abruptly returned to glacial conditions within a trend of interglacial warming and increased solar insolation. To date, the predominate idea for the trigger of this cold oscillation is a reduction in the North Atlantic's meridional overturning circulation, which may have been caused by a freshwater influx from glacial meltwater originating from the Laurentide Ice Sheet. In contrast, Firestone et al. (2007) have suggested an extraterrestrial impact over the Great Lakes region as the catalyst for this abrupt cooling. Questions remain about the forcing mechanism, global extent of the YD cooling, and how the Pacific regions responded to this climate event. Here we present data from an ultra-high resolution (>1cm/yr) marine sediment core from the Gulf of Alaska (426m), as well as data from an intermediate depth (2941m) core from the eastern equatorial Pacific, both spanning the last deglacial period. Preliminary data include stable isotopes, faunal and lithic counts, and radiocarbon dates on both benthic and planktonic foraminifera throughout the YD. The benthic/planktonic age differences vary throughout the deglacial period, with maximum differences occurring during the mid-YD. This suggests reorganization in ocean stratification and the expansion of old waters into the high latitude North Pacific.