SLS Seminar: Jess Adkins (Caltech)
"Rethinking carbon cycle feedbacks and the Urey weathering equation in the coupled carbon and sulfur system"
The coupling of the carbon and sulfur cycles over the Cenozoic are often thought about in terms of the combined burial flux of pyrite and organic matter in marine sediments. However, the weathering of pyrite generates sulfuric acid that competes with CO2 as a source of protons to weather rocks on land. This coupling of the sulfur and carbon cycles via the input to the ocean can have dramatic effects on pCO2. We have been surveying the world’s rivers for their sulfur isotope variation in dissolved sulfate. The mean value is lower than previously assumed implying that pyrite oxidation and sulfuric acid weathering are more important than previously thought. In a restricted catchment in the Andes we have shown that this process leads to weathering as a source of CO2 not a sink. We show that this chemistry can be globalized into a new negative feedback in the ice-CO2 system.
About the Speaker
I am a chemical oceanographer interested in using trace metals as tracers of environmental processes. Most of my current work is centered around the geochemical investigation of past climates. I am primarily concerned with the last few glacial/interglacial cycles that span a few hundred thousand years. It is in this time range that we have both a relatively accurate and precise understanding of age models (though they are always improving) together with large climatic shifts that require mechanistic explanation. In particular, we have an amazing record of the rapidity and magnitude of climate change from polar ice cores.
About the Series
The Atmosphere, Ocean and Climate Sack Lunch Seminar Series is an informal seminar series within PAOC that focuses on more specialized topics than the PAOC Colloquium. Seminar topics include all research concerning the science of atmosphere, ocean and climate. The seminars usually take place on Wednesdays from 12-1pm in 54-915. The presentations are either given by an invited speaker or by a member of PAOC and can focus on new research or discussion of a paper of particular interest.
