LAUSR

Significance The evolution of the Atlantic Meridional Overturning Circulation remains difficult to constrain from direct measurements. During the last glacial cycle, the strength of this circulation covaried with temperature in the North Atlantic, itself connected to Southern Hemisphere temperature. However, this interhemispheric connection was mostly studied using Greenland and Antarctic ice cores, resulting in an incomplete picture of the thermal bipolar seesaw. Using new temperature records from the Iberian Margin, a new Bipolar Seesaw Index, and Southern Hemisphere temperature simulations, we discriminate Northern Hemisphere cold events with and without massive iceberg discharges into the North Atlantic. Our data-model comparison implies a relationship that is more complex than a simple flip-flop between two climate states linked to a tipping point threshold.