The Atlantic Meridional Overturning Circulation (AMOC) is an ocean current that transports heat into the North Atlantic. Over the ice age cycles, AMOC strength and its spatial pattern varied. We tested the role of heat forcing for these AMOC changes by simulating the temperature changes of the last eight glacial cycles. In our model, AMOC shifts between four distinct circulation modes caused by heat and salt redistributions that reproduce reconstructed long-term North Atlantic SST changes.

In the geological record of the Mediterranean Sea, we find regular, dark, organic-rich intervals. The formation of these layers has been linked to climate change caused by variations of Earth’s orbit around the Sun and the orientation of Earth’s rotational axis on timescales of tens to hundreds of thousands of years. In this study we test the hypothesis derived from the geological record with a transient model and gain new insights into the link between climate change and oceanic circulation.