Deglacial changes in ocean circulation and their impact on the global carbon cycle

Date & time

1–2pm 23 November 2017

Location

Jaeger 1 Seminar Room, RSES

Speakers

Laurie Menviel (Macquarie University)

Event series

Contacts

 Adele Morrison

Atmospheric CO2 increased by 90 ppm during the last deglaciation, but the sequence of events leading to this increase remains poorly constrained and a combination of mechanisms has been invoked to explain its full amplitude. In this presentation, I will first combine numerical simulations and paleoproxy records to show that the formation of deep and bottom water at the Last Glacial Maximum was weaker than during pre-industrial times. This globally weaker ocean circulation led to a greater carbon content in the ocean, thus contributing to the low glacial atmospheric CO2 . Then, the role of changes in oceanic circulation in driving the atmospheric CO2 increase during the early part of the deglaciation, corresponding to Heinrich stadial 1 (HS1), will be discussed. I will show that an increase in Southern Hemisphere westerlies played a crucial role in leading to Southern Ocean CO2 outgassing thus inducing an abrupt atmospheric CO2 rise during HS1.

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