The Bjerknes Centre is a collaboration on climate research, between the University of Bergen, Uni Research, the Institute of Marine Research, Nansen Environmental and Remote Sensing Centre.

Deep-water circulation leads Greenland climate during the last deglaciation

 Francesco Muschitiello from Uni Research will give a seminar talk on Monday November 27 in the West wing autitorium.

Francesco Muschitiello

Short biography:

My research interests cover a broad spectrum of topics surrounding past climate dynamics. I am particularly interested in understanding the mechanisms behind rapid transitions in the climate system to create predictability for future climate change. A critical issue is to better comprehend the exact sequence of events occurring across rapid climate shifts of the past in order to discern cause-effect relationships between the different components of the global climate system (atmosphere, oceans, ice sheets and the carbon cycle).  

My research mostly involves the use of paleo-climate records from marine and lake sediment cores using a variety of inorganic and organic geochemical proxies, with a special focus on stable isotopic tracers. These proxies provide powerful tools to reconstruct changes in ocean circulation, and regional shifts in precipitation and atmospheric circulation patterns.

Further important aspects of my work involve developing robust chronologies for paleo-climate archives to better integrate climate data from marine and terrestrial records, as well as evaluating physical models in relation to past climate scenarios.

Abstract:

Constraining the response time of the climate system to changes in Atlantic Meridional Overturning Circulation (AMOC) is fundamental to improve climate predictability. Here we present a precise synchronization of terrestrial, marine and ice-core records that reveals for the first time the ocean-atmosphere lead-lag nature during rapid North Atlantic climate transitions of the last deglaciation. Using a continuous record of deep water ventilation from the Nordic Seas, we identify a systematic ∼250-year lead of deep-water export on abrupt climate changes recorded in Greenland ice cores –in and out of the Younger Dyas stadial (YD)– in response to gradual changes in freshwater forcing. Supported by transient climate model simulations, our results also point at a delayed response of atmospheric CO2 rise to AMOC slowdown at the onset of the YD. We conclude that variations in North Atlantic deep-water formation are precursors to large-scale climate and pCO2 changes, which highlights the need for improved long-term future AMOC projections.