National Center for Atmospheric Research Response to CAB Letter Bill Collins http://www.cgd.ucar.edu/~wcollins National Center for Atmospheric Research Boulder, Colorado

Summary of the CAB Letter (Thanks to Jay Fein) The growth of the CCSM project has been accomplished with essentially the same NCAR core people for at least the last six years and the toll it is taking on their professional and personal lives is clearly evident. NSF and DOE should take very seriously the problem of training the next generation of coupled system modeling scientists and developers and develop a plan to recruit and train young scientists in this area. The three versions of the CCSM have all had a similar systematic biases: for example, neither the annual mean, nor the annual cycle, nor the ENSO cycle have been adequately simulated in the coupled model. Any future use of the IPCC runs made by the CCSM for adaptation planning will depend on removing these serious biases.

Summary of the CAB Letter (cont.) We recognize that the added future complexity of the model puts additional strains on the entire system… We would like to have a report on how the program and resources have actually grown, and how whether or not the future projections still seem appropriate: in this way we can assess realistic future possibilities for the CCSM. The CAB has raised the issue of computational resources many times over past years. The situation will worsen substantially as chemistry, biology, middle atmosphere and higher resolution requirements are implemented… We again call for an aggressive national policy that recognizes this critical need and corrects it. At this winter meeting, we would like to concentrate on the national strategy for producing IPCC models and simulations.