Modelling of the end of last Ice Age in transient framework with a coupled climate model ...

• Main Author: Sun, Yuchen
• Format: Thesis
• Language: English
• Published: Universität Bremen 2022
• Subjects: Termination 1; Heinrich Stadials HS; Bølling/Allerød interstadial; Abrupt climate change; AMOC; self-oscillation; 530; Ice Sheet; NADW; North Atlantic Deep Water; North Atlantic
• Online Access: https://dx.doi.org/10.26092/elib/2101; https://media.suub.uni-bremen.de/handle/elib/6762

The last deglaciation was characterized by a sequence of abrupt climate events thought to be linked to rapid changes in Atlantic meridional overturning circulation (AMOC). The sequence includes a weakening of the AMOC after the Last Glacial Maximum (LGM) during Heinrich Stadial 1 (HS1), which ends with an abrupt AMOC recovery giving rise to Bølling/Allerød (B/A) warming. This transition occurs under a background with persistent deglacial meltwater fluxes (MWF) that are deemed to play a negative role in North Atlantic Deep Water (NADW) formation. Using a fully coupled Earth system model COSMOS with a range of deglacial boundary conditions and reconstructed deglacial meltwater fluxes, we show that deglacial CO2 rise and ice sheet decline modulate the sensitivity of the AMOC to these fluxes. While declining ice sheets increase the sensitivity, increasing atmospheric CO2 levels tend to counteract this effect. These effects, therefore, might account for the occurrence of abrupt AMOC increase in the presence of ...