Hindcasting the continuum of Dansgaard–Oeschger variability: mechanisms, patterns and timing

• Published in: Climate of the Past
• Main Authors: L. Menviel, A. Timmermann, T. Friedrich, M. H. England
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2014
• Subjects: envir; geo; Dansgaard-Oeschger events; Ice Sheet; North Atlantic
• Online Access: https://doi.org/10.5194/cp-10-63-2014; http://www.clim-past.net/10/63/2014/cp-10-63-2014.pdf; https://doaj.org/article/03b33a01cceb4351a044d9234b0b06e8

Millennial-scale variability associated with Dansgaard–Oeschger events is arguably one of the most puzzling climate phenomena ever discovered in paleoclimate archives. Here, we set out to elucidate the underlying dynamics by conducting a transient global hindcast simulation with a 3-D intermediate complexity earth system model covering the period 50 to 30 ka BP. The model is forced by time-varying external boundary conditions (greenhouse gases, orbital forcing, and ice-sheet orography and albedo) and anomalous North Atlantic freshwater fluxes, which mimic the effects of changing northern hemispheric ice volume on millennial timescales. Together these forcings generate a realistic global climate trajectory, as demonstrated by an extensive model/paleo data comparison. Our results are consistent with the idea that variations in ice-sheet calving and subsequent changes of the Atlantic Meridional Overturning Circulation were the main drivers for the continuum of glacial millennial-scale variability seen in paleorecords across the globe.