RECONSTRUCTION OF ATLANTIC MERIDIONAL OVERTUNING CIRCULATION DURING THE YOUNGER DRYAS WITH IMPLEMENTATION OF A CARBON CYCLE MODEL

Several hypotheses have been proposed regarding the cause of the Younger Dryas cooling period occurred approximately 12,900 years before present. The most widely accepted hypothesis, proposed by Broecker et al. (1989), suggests the Younger Dryas was prompted by a reduction of North Atlantic Deep Water (NADW) formation, which caused a shutdown of the Atlantic meridional overturning circulation (AMOC). Using the fully coupled version of the Community Climate System Model version 3 (CCSM3) from the National Center for Atmospheric Research (NCAR), we aim to reproduce experiments conducted by Liu et al. (2009) and He (2011) to reinforce their findings and gain a solid understanding of how the Younger Dryas began. Two experiments have been designed and integrated with the CCSM3 model. A carbon cycle has been added to the experiments (The Ocean-Carbon Cycle Model Intercomparison Project Phase 2 (OCMIP2)). The first experiment implements freshwater forcing, transient orbital parameters and transient greenhouse gas settings. The second, a control, uses no freshwater forcing and uses present day settings for both orbital parameters and greenhouse gases. It is expected that the experiment with freshwater forcing and transient settings will adequately represent the findings from He (2011), suggesting that the input of glacial discharge into the Northern Atlantic is a viable mechanism for the start of the Younger Dryas cooling event.