Prof. Dr. Ulrich G. Wortmann 

Understanding ocean chemistry in a warming world

The ocean absorbs large amounts of carbon dioxide, buffering much of the anthropogenic CO2 release. The oceans buffering capacity depends on the interaction of biological and chemical processes, e.g., photosynthesis and organic matter decomposition. These are processes understood well enough to create computer models that accurately describe, e.g., ocean acidification in response to the anthropogenic CO2 release.

Current ocean models typically assume that there is always enough oxygen to facilitate organic matter decomposition. However, increasing temperatures will reduce marine oxygen concentrations, possibly to the point of complete oxygen loss. Earth history is indeed full of examples where this process resulted in large ocean areas devoid of oxygen, inhospitable to all higher life forms. The transition from oxygen bearing to oxygen free waters, not only affects higher life forms, but also fundamentally affects the oceans ability to absorb CO2 (aka alkalinity).

This project aims to understand how the changeover from oxygen based to sulfate based organic carbon remineralization changes the distribution of alkalinity between the surface and intermediate waters, and how this affects atmospheric pCO2.