Explaining the continuum of Dansgaard-Oeschger variability
Hovedinnhold
Axel Timmermann (University of Hawaii, US):
Explaining the continuum of Dansgaard-Oeschger variability
Abstract
Millennial-scale variability associated with Dansgaard Oeschger (DO) and Heinrich events (HE) is one of the most puzzling glacial climate phenomena ever discovered in paleo-climate archives. The presentation will describe the results of the first transient global climate hindcast simulation covering the period 50 ka B.P. to 11 ka B.P. The climate model is forced by time-varying external boundary conditions (greenhouse gasses, orbital forcing, and ice-sheet orography and albedo) and anomalous North Atlantic freshwater fluxes, which mimic the effects of changing Northern Hemisphere ice-volume on millennial timescales. Together these forcings generate a realistic global climate trajectory, as demonstrated by an extensive model/paleo data comparison. The analysis presented is consistent with the idea that ice-sheet instabilities and subsequent changes of the Atlantic Meridional Overturning Circulation were the main driver for the continuum of DO and HE variability seen in paleo-records across the globe.