Marine Carbon and Ecosystem Feedbacks in the Earth System

Why?

The centennial trend and decadal variability of the ocean carbon uptake poses many important but unanswered questions, especially in the Southern Ocean. The biological carbon pump, that is the biomass production by phytoplankton during photosynthesis and the subsequent sinking of some of that organic carbon to the deep sea where it can be stored for hundreds to thousands of years, is important for ocean carbon uptake, marine ecosystems, and atmospheric CO2 concentration. Yet, potential future changes of the biological carbon pump are still relatively uncertain, and we just begin to understand processes behind these changes in model simulations. Earth System Models lag behind in incorporating relevant biological dynamics which might be important in order to obtain more robust projections of the Earth System.

Our approach

We combine the unstructured mesh ocean model FESOM in the stand-alone version and in the AWI-CM version (FESOM coupled to an atmospheric model) with our non-Redfield ecosystem model REcoM. We incorporate recent process-understanding of biological processes (phytoplankton senstivity to multiple stressors, zooplankton grazing) in collaboration with phytoplankton and zooplankton experts at AWI and Uni Bremen. We will apply this model to simulate the historical period and the coming decades and analyse the model results to understand the processes behind feedbacks in the carbon cycle and in the marine ecosystem.