Simulating Earth System Feedback's Over Time: The importance of organic matter cycling

How is Earth’s climate regulated on geologic timescales, and what is the role of organic matter (OM) cycling in this? Disentangling and quantifying the feedbacks involved is essential for understanding Earth’s biogeochemical history and the long-term consequences of future climate change. This talk provides a brief overview of some of the processes I have studied so far to help answer these questions and introduces my main numerical tools in this endeavor: (i) OMEN-SED, a computationally efficient early diagenetic model that features a state-of-the-art representation of OM degradation dynamics, and (ii) cGENIE, the first fully-coupled 3D Earth system model that includes mechanistic representations of terrestrial weathering and carbon-phosphorous sedimentary cycling. First, I will show how we implement OMEN-SED on a 0.25° x 0.25° grid of global continental margin sediments to quantify OM reactivities and sequestration rates in the modern ocean. Our results represent the first spatially resolved budget of one of the least constrained fluxes in the global carbon budget and can be used to conduct regional analyses of this natural carbon sink. Second, I will present how we use cGENIE to interpret information stored in sediment archives, thus exemplifying powerful ways to combine spatially resolved numerical modelling with proxy observations to understand Earth’s biogeochemical history. Finally, I will show that faster feedbacks involving OM cycling are critical for regulating Earth’s climate and that they may create unexpected instability in the Earth system.