NOAA/WDS Paleoclimatology - Lake Hayes, New Zealand Last Deglacial Biomarker and Carbonate Data

Millennial-scale climate anomalies punctuating the last deglaciation were expressed differently in the Northern and Southern Hemispheres. While oceanic meridional overturning has been invoked to explain these disparities, the nearly synchronous onset of such events requires atmospheric mediation. Yet the extent and structure of atmospheric reorganization on millennial timescales remains unclear. In particular, the role of the Southern Hemisphere westerly winds (SHWW) and associated storm tracks is poorly constrained, largely due to the paucity of accessible archives of wind behavior. Here we present a new paleohydrologic record from a Lake Hayes, New Zealand (45 S) sediment core spanning ~17 ka. Using two independent proxies for lake hydrology (Ca/Ti in sediments and dD values of aquatic plant biomarkers), we find evidence for a wetter Antarctic Cold Reversal (ACR, 14.7-13.0 ka) and a drying trend during the Younger Dryas (YD, 12.9-11.6 ka) and early Holocene (11.7 ka onward in this record). Comparisons of the Lake Hayes record with other Southern Hemisphere sites indicate coherent atmospheric shifts during the ACR and YD. Several mechanisms, such as the retreat of Antarctic sea ice, could explain the shifts in the westerlies and decoupling between Southern Hemisphere low- and mid-latitude climates in the early Holocene.