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3. If U.S. scientists lose involvement in high-end modeling activities, they may miss opportunities to gain valuable insights into the underlying processes that are critical to subsequent modeling investigations. In this regard the issue of accessibility is much more than just a commercial and political issue; in order to most effectively advance the science in the United States, researchers need to have access to both model output and the models themselves to iteratively diagnose the output, advance knowledge of climate, and improve the models' predictive capabilities.

4. There are currently relatively few modeling centers anywhere in the world capable of producing moderate resolution (e.g., 250–300 km grid spacing), transient climate simulations. The differences in simulated climate produced by each of these models' different structures help to bound the range of outcomes that the climate system might produce given a certain forcing scenario. Thus, the state of climate modeling throughout the world is such that the addition or removal of even a single model could affect the confidence levels assigned to certain scenarios of future climate change. In other words, not only would the United States benefit from enhancements in its modeling capabilities, the international community would benefit from these efforts as well. The marginal benefits from only modestly increased investments in comprehensive models in the United States could be very large, because, if properly coordinated, the enhanced emphasis on highend modeling could be built upon the excellent existing U.S. strength in small and intermediate modeling.

Thus, to facilitate future climate assessments, climate treaty negotiations, and our understanding and predictions of climate, it is appropriate to develop a national climate modeling strategy that includes the provision of adequate computational and human resources and is integrated across agencies.