Celebrating Two Decades of the Program for Climate Model Diagnosis and Intercomparison

What: to celebrate the twentieth anniversary of PCmDi and to honor its founder, w. lawrence gates, more than 100 specialists and leaders in climate modeling met to discuss PCmDi’s history and the future of climate modeling When: 6 april 2009 Where: bethesda, maryland T wenty years ago, W. Lawrence (Larry) Gates approached the U.S. Department of Energy (DOE) Office of Energy Research (now the Office of Science) with a plan to coordinate the comparison and documentation of climate model differences. This effort would help improve our understanding of climate change through a systematic approach to model intercomparison. Early attempts at comparing results showed a surprisingly large range in control climate from such parameters as cloud cover, precipitation, and even atmospheric temperature. The DOE agreed to fund the effort at the Lawrence Livermore National Laboratory (LLNL), in part because of the existing computing environment and because of a preexisting atmospheric science group that contained a wide variety of expertise. The project was named the Program for Climate Model Diagnosis and Intercomparison (PCMDI), and it has changed the international landscape of climate modeling over the past 20 years. In spring 2009 the DOE hosted a 1-day symposium to celebrate the twentieth anniversary of PCMDI and to honor its founder, Larry Gates. Through their personal experiences, the morning presenters painted an image of climate science in the 1970s and 1980s, that generated early support from the international community for model intercomparison, thereby bringing PCMDI into existence. Four talks covered Gates’s early contributions to climate research at the University of California, Los Angeles (UCLA), the RAND Corporation, and Oregon State University through the founding of PCMDI to coordinate the Atmospheric Model Intercomparison Project (AMIP). The speakers were, in order of presentation, Warren Washington [National Center for Atmospheric Research (NCAR)], Kelly Redmond (Western Regional Climate Center), George Boer (Canadian Centre for Climate Modelling and Analysis), and Lennart Bengtsson [University of Reading, former director of the European Centre for Medium-Range Weather Forecasts (ECMWF)]. The afternoon session emphasized the scientific ideas that are the basis of PCMDI’s success, summarizing their AFFILIATIONS: Potter—University of California Davis, Davis, California; bader—oak ridge national laboratory, oak ridge, tennessee; riChes and josePh—office of biological and environmental research, U.s. Department of energy, washington, D.C.; baMzai—Climate and large-scale Dynamics Program, national science foundation, arlington, Virginia CORRESPONDING AUTHOR: gerald l. Potter, Department of geology, University of California, Davis, one shields avenue, Davis, Ca 95616 e-mail: jpotter@ucdavis.edu