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COUPLING THE ORNL AND GISS MODELS 



The general .methodology for estimating thermal expansion of 

 the oceans was outlined in Figure B-l. Of the two pathways for 

 translating carbon emissions from fossil fuel combustion into 

 atmospheric CO2 concentrations (assuming a retention factor and 

 running the ORNL model), this section focuses on the use of the 

 ORNL model. As discussed previously, using the ORNL model to 

 estimate atmospheric concentrations of CO2 requires the coupling 

 of the ORNL and GISS models and an iterative procedure using the 

 GISS model alone. The discussion in this section emphasizes the 

 sequence of actions employed to couple the two models, and the 

 procedures for iterating within the GISS model. 

 Calculating Initial Temperature vs. Time Curves 



The starting point for the analyses that use the ORNL 

 model is the estimation of a family of temperature-time curves 

 using the GISS model. These curves are employed in the ORNL 

 model to describe a range of future increases in sea surface 

 temperature (in response to rising atmospheric CO2) which, in 

 turn, will affect the rate of CO2 exchange among sources and 

 sinks. Essentially, the time trends of temperature, generated 

 by a fairly sophisticated treatment of heat flux in the GISS 

 model, replace the very simple C02 _ temperature relationships in 

 the ORNL model. The treatment of heat flux in the GISS model is 

 still a highly simplified representation of real ocean transports, 



