Using paleo-oceanographic data synthesis to test ideas about changes in atmospheric CO2 concentrations during glacial inception

Several hypotheses have been put forth to explain the 80 –100 ppm change in atmospheric carbon dioxide concentrations that has occurred consistently on glacial-interglacial timescales over the past 800,000 years (Sigman et al. 2010). A combination of process-based modelling and paleo-environmental data from the geological record suggest that while changes in ocean biology have likely played a role as an important feedback mechanism, changes in marine biology alone cannot explain the full glacial-interglacial change in atmospheric carbon dioxide concentrations (Kohfeld et al. 2005, Kohfeld and Ridgwell 2009). This result points towards an important, triggering role of physical changes in the global ocean as a main driver of changes in atmospheric carbon dioxide concentrations, in particular during the earliest part of the glacial cycle.