This PhD project by Yvan Romé explored the occurrence of millennial-scale variability in the HadCM3 general circulation model during the last glacial period and, in particular, the last deglaciation. To identify the range of climate conditions and the mechanisms behind glacial millennial-scale variability, new sets of multi-millennial HadCM3 simulations forced with deglacial patterns of meltwater forcing were created. This includes simulations of the last glacial maximum forced with fixed meltwater discharges derived from the ice sheet melting history showing a pseudo-oscillating behaviour under the right balance of magnitude and location of the freshwater forcing. The oscillating simulations were analysed in more detail through multiple sensitivity analyses to map the salinity fluxes in the critical convection regions. Finally, the meltwater discharge protocol was applied to transient simulations of the last glacial maximum using two different ice sheet reconstructions.
The data included in this project's dataset consists mainly of model outputs that focus on the main mechanisms at stake in glacial climate variability, namely the changes in AMOC regimes, the reorganisation of ocean masses and the effect of the ice sheet reconstruction. They provide unique support for studying the occurrence of climate variability on different timescales in general circulation models and the potential chain of events of the last deglaciation.
This work was funded by the Natural Environment Research Council's Panorama doctoral training partnership.