Stirring Things Up - Productivity Boost or Just a Drain? Nutrient Sensitivity to Meridional Overturning in the Pliocene

Interest in the behavior of ocean circulation in our warmer future has largely focused on the North Atlantic Meridional Overturning Circulation (AMOC), suggesting AMOC weakening or collapse. On the other hand, climate modeling and geologic data indicate the development of Pacific Meridional Overturning (PMOC) during a number of warm climates in Earth's past. We compare several biogeochemistry and carbon-isotope enabled simulations of Pliocene-like conditions on Earth System (millennial) timescales and their resulting changes in global and Pacific overturning. Despite PMOC development in all of these simulations, it is of varying strength and depth. Our work explores the implications of this variability in PMOC character for nutrient levels and carbon isotopes in the North Pacific. Further, we discuss how foraminifera carbon isotope and faunal assemblage model-proxy comparisons can constrain which regime was more likely to have occurred during the actual Pliocene.