A Flexible Climate Model For Use In Integrated Assessments

Because of significant uncertainty in the behavior of the climate system, evaluations of the possible impact of an increase in greenhouse gas concentrations in the atmosphere require a large number of long term climate simulations. Studies of this kind are impossible to carry out with coupled atmosphere ocean general circulation models (AOGCMs) because of their tremendous computer resource requirements. Here we describe a two-dimensional (2D, zonally averaged) atmospheric model coupled with a diffusive ocean model developed for use in the integrated framework of the MIT Joint Program on the Science and Policy of Global Change. The 2D model has been developed from the GISS GCM and includes parameterizations of all the main physical processes. This allows it to reproduce many of the nonlinear interactions occurring in simulations with GCMs. Comparisons of the results of present-day climate simulations with observations show that the model reasonably reproduces the main features of the zonally averaged atmospheric structure