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In addition to changing some of the parameters and operational 

 procedures of both the GISS and ORNL models, additional programs 

 were developed to provide simple interfaces between these two 

 models and to permit more rapid and extensive sensitivity analyses. 

 Separate sections of this appendix describe the individual models 

 and procedures for operating and combining them in the context 

 of this study, as well as the specific assumptions used to run 

 the scenarios. 



THE ORGANIZING FRAMEWORK USED 



The assumptions, relationships, and models used to estimate 

 sea level rise are shown in Figure B-l. The key variables are 

 described as primary inputs or outputs of the three models or 

 are subsumed in the internal structures of the models. 



As shown in Figure B-l, the three models are operated in 

 sequence. The IEA model is first run to generate future energy 

 use and carbon emission scenarios. The ORNL model (or an assumed 

 constant fraction of CO2 airborne) is next used to translate 

 fossil-fuel carbon emissions into atmospheric CO2 levels. The 

 GISS model is finally employed to translate increases in CO2 

 concentrations into atmospheric temperature increases and sea 

 level rise. (The temperature of the atmosphere at the earth's 

 surface is assumed equal to the temperature of the ocean's top 

 layer.) The GISS model uses a variety of key assumptions as 

 inputs: trace gas growth, thermal sensitivity of the atmosphere, 

 and changes in other forcings. 



