Simulated Ocean Circulation and Marine Carbon Cycle during the Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene Thermal Maximum (55 Mya) is regarded as a suitable analog to future climate change and uptake of carbon in the ocean. For this time, significant changes in climate and geochemistry have been inferred from temperature proxies and stable carbon isotope ratios. The carbon and nutrient cycles have been incorporated into the community climate system model (CCSM-3) in order to explore effects of a massive carbon release into the atmosphere on changes in the carbon uptake. A silicate cycle and a sediment component are currently under development.

A new marginal sea parameterization for the Arctic Ocean has been introduced to allow a better estimate of the exchange of water masses of the Arctic with the adjacent oceans. With this improvement, the simulated Paleo-Atlantic deep-sea circulation indicates a southward transport into the Southern Ocean in agreement with stable carbon isotope reconstructions. The deepwater formation in the North Pacific and Southern Ocean is associated with high productivity. Simulated temperatures predicted from an 8 x CO2 PETM run are significantly lower than recent temperature reconstructions from oxygen isotopes, TEX86, and Mg/Ca data. Thus, simulations with even higher greenhouse gas concentrations may be required to yield a better match with the reconstructed temperatures for the PETM.