Session: Invited talks
Author: Zhengyu Liu / email@example.com / Ohio State University
The responses of AMOC to the deglacial change of atmospheric greenhouse gases (GHG), ice sheet and meltwater forcing (MWF) is discussed using the TRACE21 simulations and the implication to the present and future AMOC is discussed. During the deglaciation, AMOC intensity is strengthened in response to the slow rise of atmospheric GHG, opposite to the weakening forced by the rapid increase of GHG in the future. In the meantime, AMOC intensity is weakened in response to the ice sheet retreat, which opposes the AMOC response to GHG such that the strength of AMOC is not changed significantly between LGM and the present. In both the AMOC responses to GHG and ice sheet, sea ice feedback plays a critical role. Furthermore, our model fails to produce the abrupt change of AMOC in response to deglacial MWF unless the MWF is prescribed to change abruptly. This may be an artifact of a model bias related to the present day freshwater budget that is common across all present coupled general circulation models (CGCMs). This overstabilization of AMOC may have underestimated the possibility of abrupt AMOC response and climate change to global warming in the future.