Global carbon cycle response to Milanković forcing

To gain a deeper understanding of why atmospheric CO₂ varied on Milanković timescales, we conducted a 3 million-year transient carbon cycle simulation with the intermediate-complexity Grid Enabled Integrated Earth System (cGENIE). To this end we nudged ocean temperature and salinity obtained from a previously conducted 3 million-year climate simulation conducted with the Community Earth System Model (CESM1.2) into the cGENIE ocean model. The cGENIE model captures key processes relevant for the longterm behaviour of the carbon cycle, including ocean biogeochemistry, vegetation, land surface weathering and sedimentary dynamics. Here we will present the first results from a series of transient glacial-interglacial simulations cGENIE simulations which identify the role of ocean circulation, sea ice, solubility and land vegetation changes as drivers of low frequency pCO₂ variability. We will further discuss the effects of iron fertilization and carbonate compensation.