Lecture: Emergency Exit? Mitigation of extreme Oceanic Anoxic Event conditions by organic matter…

Emergency Exit? Mitigation of extreme Oceanic Anoxic Event conditions by organic matter sulfurization in the late Cretaceous Ocean

Lecture by Dr. Sandra Arndt, 2023 EAG Distinguished Lecturer
Recorded at Institute of Geography and Earth Sciences, Eotvos University Budapest, Hungary
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The geologic record contains evidence of massive greenhouse gas releases to the atmosphere in the distant past. A number of negative carbon-cycle climate feedbacks help the Earth System to recover from the resulting greenhouse climates by removing the excess carbon and bury it in a form that will not quickly leak back to the atmosphere.

The late Cretaceous is marked by a series of extreme greenhouse events that turned the ocean anoxic. Under these extreme conditions, different mechanisms can make organic carbon less reactive, thus preserving and burying more carbon in marine sediments. One of these mechanisms is the sulfurization of organic matter- the reaction of organic carbon with hydrogen sulfide to form new molecules that are more resistant to being broken down by bacteria.

I illustrate how we used the geological record together with a global carbon-cycle-climate model to help understand the importance of organic matter sulfurization during the Ocean Anoxic Events 2 (‘OAE2’) and test if the amount of carbon buried helps the Earth system in recovering from greenhouse climates.

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Sandra Arndt is based at the Geosciences, Environment and Society Department at the Université Libre de Bruxelles, Belgium, where she is an Associate Professor in Geology.

Sandra’s research focuses on improving our understanding of carbon cycle-climate feedbacks and their role in determining the magnitude and pace of climate change. To address these research questions, she develops and applies numerical models that synthesize our current understanding of ocean carbon cycling across traditional disciplinary and ecosystem boundaries.