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William H. Goldstein
Associate Director for Physical and Life Sciences

A New Era in Climate System Analysis

IN 2010, the American Meteorological Society presented the Laboratory’s Program for Climate Model Diagnosis and Intercomparison (PCMDI) with a special award. PCMDI, the society said, had pioneered “a new era in climate system analysis and understanding” and has “really changed the way we do business in climate science.”

What is this transformation in climate science that Livermore scientists have led? Through their work, they have revolutionized the openness and ease with which researchers worldwide access and analyze model simulations of climate and climate change. Their work has not only led to a better fundamental understanding of the global climate system, but it has also greatly enhanced the ability of scientists to scrutinize, evaluate—and, thus, improve—climate models.

It is difficult to overstate the importance of this work, especially in light of the debate over the causes and consequences of global warming. The scientific community, policy makers, and the general public all need a means for understanding the differences between climate models and for characterizing these models’ uncertainty. PCMDI, which is sponsored by the Office of Biological and Environmental Research at the Department of Energy, is a critical source for this type of information.

PCMDI does not develop or run its own climate model. Because the program does not have a vested interest in the results produced by a particular model, it can maintain a rigid objectivity in its assessment of climate models. PCMDI thus enjoys an international reputation for neutrality. It is a trusted agent for hosting, managing, and presenting climate simulation output without bias. The confidence earned by PCMDI partly explains the international modeling community’s willingness to freely share output. This open sharing of results expands the expertise that can be brought to bear in assessing models and thus helps accelerate advances in climate science.

The reliance of the world’s climate community on PCMDI is increasing, as these scientists engage in the fifth installment of the Coupled Model Intercomparison Project (CMIP5). The CMIP methodology, which was developed at Livermore, systematically compares and evaluates climate simulations with respect to each other and to climate measurements. Its results have informed the series of reports issued by the United Nations–sponsored Intergovernmental Panel on Climate Change, which is at work on its fifth assessment report.

At the same time, PCMDI is expanding its efforts in response to the need for better methods of evaluating the validity and accuracy of climate models. As part of CMIP5, for example, PCMDI will apply new methods for diagnosing the effects of cloud and carbon cycle changes on climate projections. In a major effort, funded by the Laboratory Directed Research and Development Program, climate scientists at Livermore are seeking to apply the tools of uncertainty quantification, which are used to evaluate the simulations that underlie nuclear stockpile stewardship, to climate modeling. If successfully developed, this approach will revolutionize the ability to quantify scientific confidence in predictions of future climate patterns.

The climate program at Livermore, which is featured in Seeking Clues to Climate Change, exemplifies our defining theme of science in the national interest. Through sustained innovation, excellence, objectivity, and service, PCMDI has earned the trust and recognition summarized in the citation by the American Meteorological Society.

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