Oceanic carbon cycling response to global temperature changes
Human-caused emissions of carbon dioxide are disrupting the natural variations of the carbon cycle. Past climatic variations provide essential information on the carbon cycling and its associated climate changes to explore different scenarios from unrestrained to even decreased emissions of CO2. In the CYCLOCARB project, we will develop a semi empirical model of carbon cycling and climates over the last glacial cycle, a unique dampened natural analogue for expected anthropogenic forcing’s. This semi-empirical model will be constrained by an extensive database including indicators for temperature and ice volume (δ18O of foraminifers, sea surface temperature proxies) and proxies for global carbon cycling and partitioning between ocean, atmosphere and solid earth (δ13C of foraminifers, carbonate, organic carbon content in marine sediment). Temperature proxies’ records will help refining climatic sensitivity to greenhouse gases, and the temporal evolution of temperature pattern will shed light on the response of the oceans to climate forcing’s. The δ13C of the climatic system will be reconstructed and the effect of the biological pump quantified for the last 150ka, encompassing both a major emission event at termination II and some decreased CO2 intervals. Altogether, our climatic reconstructions and the semi-empirical model will improve our understanding of the natural response of the carbon cycling to anthropic changes. Moreover, CYCLOCARB will permit the quantification of carbon stocks in Exclusive Economic Zones, which could affect Europe national greenhouse gases inventories and marine carbon stock management.