It is the assessment of this committee that a number of efforts in the United States meet some or all of these criteria. The two core modeling efforts that meet all of the criteria are
• the National Center for Atmospheric Research (NCAR), supported by NSF and the Department of Energy (DOE); and
• the Geophysical Fluid Dynamics Laboratory (GFDL), supported by NOAA.
Additional efforts that meet some of the criteria are
• the Goddard Institute for Space Studies (GISS), supported by NASA, focusing on decadal to centennial climate change;
• the National Centers for Environmental Prediction (NCEP), supported by NOAA, focusing on seasonal prediction; and
• the Goddard Global Modeling and Assimilation Office (GMAO), supported by NASA.
This somewhat distributed system for U.S. model development has evolved over more than three decades with a legacy of funding support among different agencies, as well as differing modeling missions. Early results from the GFDL and GISS models provided much of the basis for the NRC (1979) assessment of the climate change expected from increasing carbon dioxide. NCAR began global modeling activities in the 1960s. Efforts in global modeling were also initiated at a number of universities, such as the University of California, Los Angeles. In part because of the large infrastructure that is required on an ongoing basis, the efforts at comprehensive global climate system modeling in the United States are primarily sustained at large national centers, while drawing upon expertise from universities and other partners. The GFDL and NCAR modeling efforts continue to focus on modeling of climate change and variability on time scales of seasons to centuries, with a strong emphasis on long-term projections. NCAR has partnered with DOE and the university research community to help provide the scientific and computational resources needed to sustain its effort. NASA-GISS, at a much smaller level, has also continued to focus on long-term climate change. All three centers have contributed to the Intergovernmental Panel on Climate Change assessments since they began. GFDL and NCAR were designated as the two primary U.S. climate modeling centers in the 2003 report of the U.S. Climate Change Science Program (CCSP1) (CCSP, 2003).
Other major U.S. global modeling activities have focused on other objectives: NCEP on operational weather and climate predictions on time scales from days to seasons, and
1 CCSP is now known as the U.S. Global Change Research Program (USGCRP).