The disintegration of the Northern Hemisphere ice sheets during glacial terminations leads to multiple complex feedback loops that are still poorly understood. To study them, we use here a fully coupled climate – Northern Hemisphere ice sheet model to simulate the last two glacial terminations.
We show that although the first-order climate trajectory is similar for the two terminations, differences in solar insolation lead to significant differences. Warmer temperatures during the penultimate termination explain a more rapid retreat of the ice sheets and are consistent with a higher sea level during the last interglacial period compared to the Holocene. In our simulations, the Greenland ice sheet contribution to sea-level rise during the last interglacial is around 2m. We also simulate a warming of the subsurface Southern Ocean, compatible with an additional contribution from the Antarctic ice sheet. In addition, the two terminations have different sensitivities to the Atlantic overturning circulation, which is more likely to collapse
during the penultimate termination. Finally, using additional sensitivity experiments, we show that, for both terminations, Northern Hemisphere insolation is the main driver of ice sheet retreat, although changes in vegetation must also be taken into account to explain the total amplitude of sea-level change.
Authors: Aurélien Quiquet and Didier Roche