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Seminar talk: Antarctic sea-ice control on glacial and modern deep-ocean circulation and carbon storage

Alice Marzocchi from National Oceanography Centre in Southampton will give a seminar talk on March 18, 2019

Portrait Marzocchi
Alice Marzocchi


Short biography:

Alice Marzocchi is a Research Scientist at the National Oceanography Centre in Southampton (UK). Until February 2018, she was a Postdoctoral Scholar at the University of Chicago. She obtained a PhD in paleoclimate modelling from the University of Bristol in 2016 and she was also a Visiting Research Fellow at Utrecht University. She completed her undergraduate studies in Environmental Sciences at the University of Bologna and an MSc in Physical Oceanography at the University of Southampton.

Alice’s research combines numerical models and observations, to better understand past and present ocean and climate dynamics and to simulate how these may change in the future. She is especially interested in high-latitude processes. Her most recent project focuses on regional changes in ocean heat content, investigating where heat is taken up from the atmosphere and how it is transported and redistributed by ocean currents.






Paleoceanographic reconstructions indicate that the distribution of global ocean water masses has undergone major rearrangements on glacial-interglacial time scales. Different rates of Antarctic sea-ice formation, which plays a key role in shaping the abyssal overturning circulation today, may have driven these past circulation changes. This mechanism is investigated in preindustrial and Last Glacial Maximum (LGM, ~21,000 years ago) fully-coupled climate simulations, which are also compared to an idealised ocean model. The coupled simulations show substantial inter-model differences in their representation of glacial ocean circulation, which is often at odds with the geological evidence. Such inconsistencies are attributed to differing (and likely insufficient) Antarctic sea-ice formation, where discrepancies are further amplified by short integration times. The idealised simulations, forced solely by atmospheric cooling, reproduce circulation patterns that are broadly consistent with LGM reconstructions. The effect of Antarctic sea-ice expansion on the simulated glacial circulation and air-sea gas exchange results in increased deep-ocean carbon storage. These physical changes alone are sufficient to explain about half of the glacial-interglacial variations in atmospheric CO2 concentrations, highlighting a direct link between atmospheric cooling, reorganisation of deep-ocean water masses and glacial CO2 drawdown.


Arranged date for the seminar talk: Mar 18, 2019

Place: BCCR lecture room 4020, Jahnebakken 5