U51A-06:
Carbon isotopes support Atlantic Meridional Overturning Circulation decline as a trigger for early deglacial CO2 rise
Friday, 19 December 2014: 9:26 AM
Andreas Schmittner, Oregon State University, College of Earth, Ocean, and Atmospheric Sciences, Corvallis, OR, United States and David C Lund, University of CT at Avery Point, Groton, CT, United States
Abstract:
The mechanism for the observed initial rise of atmospheric CO2 during the last deglaciation remains unknown. Most recent hypotheses invoke Southern Hemisphere processes such as shifts in mid-latitude westerly winds. Here we compare simulations from a global, coupled climate-biogeochemistry model including carbon isotopes (δ13C) with a synthesis of high-resolution deep sea δ13C reconstructions as well as ice core data. The reconstructions from Heinrich Stadial Event 1 (19–15 ka BP) are constistent with model simulations of a large multi-millennial reduction of the Atlantic Meridional Overturning Circulation (AMOC). Our results suggest that the rise in atmospheric CO2 and decrease in its δ13C composition (δ13CCO2) observed during the early deglacial may have been caused by an AMOC induced decline of the ocean’s biologically sequestered carbon storage without the need to invoke changes in Southern Hemisphere winds.
