A Revised Temperature-Dependent Remineralization Scheme for the Community Earth System Model (v1.2.2)

Abstract. Export of carbon from the euphotic zone to intermediate and deep water plays a critical role in the ocean’s feedback response to a warming climate. However, as water temperature increases so does the rate of bacterial respiration at the base of the biological pump, resulting in more efficient recycling of carbon in the upper ocean, less efficient export of carbon to depth, and a diminished net negative feedback on climate. Therefore, to better predict climate response associated with changes in ocean carbon storage in warming scenarios, it is imperative to incorporate temperature-sensitive mechanisms, such as bacterial respiration (remineralization), into Earth system models. Here, we employ a new temperature-dependent parameterization for remineralization (Tdep) in the Community Earth System Model version 1 (CESM1) applied to gravitationally sinking particulate organic carbon (POC) in a preindustrial control simulation. We find that the inclusion of Tdep in both low and high-resolution model configurations more accurately captures regional heterogeneity in POC transfer efficiency while preserving the overall trends in nutrient distribution and attenuation of sinking particulate matter when compared with modern empirical data. Inclusion of this parametrization will allow for improved predictions of temperature-sensitive mechanisms impacting carbon storage in the warming ocean.