The ocean carbon cycle in the NASA-GISS climate model
Working title: The (aspiring?) GISS Earth System Model: the ocean carbon cycle
Working title II: Flash-sideways in the carbon world

The ocean plays a major role in regulating the atmospheric greenhouse gas concentrations 
produced by natural and anthropogenic processes.  The oceanic drawdown/outgassing of 
CO2 is determined by the solubility pump, i.e.  physical ocean processes (air-sea 
interaction, convection and the thermohaline circulation) and by the biological pump, i.e. 
the carbon removal from the atmosphere by the sea organisms through photosynthesis 
and respiration, its transport to the deep ocean and its sedimentation there.  Changes in 
the atmospheric concentrations of CO2 due to natural or anthropogenic factors result in 
changes in the behavior of these pumps which in turn further adjust (positively or 
negatively) the atmospheric concentrations of CO2.  Apart from the main feedback to the 
atmosphere, other, not necessarily secondary feedbacks, involve changes to the oceanic 
biodiversity, acidification, ocean mixing and the ocean surface albedo.  For these reason, 
the correct estimation of the sign and magnitude of carbon climate feedbacks is featured 
as a major unresolved task in the upcoming IPCC AR5 report.  

In this talk, I will give an overview of the ocean carbon modeling effort at NASA-GISS 
which consists of coupling the  NASA Ocean Biogeochemical Model (NBOM) 
developed by Watson Gregg to two ocean models, the Russell ocean model and  
HYCOM, which employ different geometry and vertical coordinate systems. 
Preindustrial spin ups are under way to determine the initial conditions for the 20th 
century transient runs that will help evaluate the model performance.