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Deep-water circulation changes lead North Atlantic climate during deglaciation

Nov 4, 2019, 1:15 pm
MARUM Research Seminar
MARUM I, room 2070

Francesco Muschitiello

University of Cambridge, United Kingdom

Constraining the response time of the climate system to changes in North Atlantic Deep Water (NADW) formation is essential to improving future climate and Atlantic Meridional Overturning Circulation 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 high-latitude NADW strength during the last deglaciation. Using a continuous record of deep-water ventilation from the Nordic Seas, we identify a systematic ~400-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 wind-driven 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 suggest that variations in NADW formation are precursors to large-scale climate and pCO2 changes during the last deglaciation, emphasizing the central role of ocean circulation in abrupt climate change.

Francesco Muschitiello
Francesco Muschitiello