Abstract

Constraining the response time of the climate system to changes in Atlantic Meridional Overturning Circulation (AMOC) is essential to improving future climate predictability. Here we present a precise synchronization of terrestrial, marine, and ice-core records, which allows for the first time a quantitative determination of the response time of North Atlantic climate to changes in AMOC strength during the last deglaciation. Using a continuous record of deep-water ventilation from the Nordic Seas, we identify a systematic 300-year lead of changes in deep-water convection ahead of abrupt climate changes recorded in Greenland ice cores at the onset and end of the Younger Dryas stadial (YD), which likely occurred in response to gradual changes in freshwater forcing. Supported by transient climate model simulations, our results also indicate a ~400-year delay in the rise of atmospheric CO2 in response to AMOC slowdown at the start of the YD. We conclude that variations in North Atlantic deep-water formation are precursors to large-scale climate and pCO2 changes, highlighting the need for improved long-term future AMOC projections.