Modeling Northern Hemisphere ice-sheet distribution during MIS 5 and MIS 7 glacial inceptions

The present manuscript compares Marine Isotope Stage 5 (MIS 5, 125-115 kyr BP) and MIS 7 (236-229 kyr BP) with the aim to investigate the origin of the difference in ice-sheet growth over the Northern Hemisphere high latitudes between these last two inceptions. Our approach combines a low resolution coupled atmosphere-ocean-sea-ice general circulation model and a 3-D thermo-mechanical ice-sheet model to simulate the state of the ice sheets associated with the inception climate states of MIS 5 and MIS 7. Our results show that external forcing (orbitals and GHG) and sea-ice albedo feedbacks are the main factors responsible for the difference in the land-ice initial state between MIS 5 and MIS 7 and that our cold climate model bias impacts more during a cold inception, such as MIS 7, than during a warm inception, such as MIS 5. In addition, if proper ice-elevation and albedo feedbacks are not taken into consideration, the evolution towards glacial inception is hardly simulated, especially...