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The Philosophy, Science, and Technology program at Georgia Tech invites you to a talk by Dr. Johannes Lenhard:
"Limits of Analysis. Holism and the Validation of Complex Climate Simulations"
Abstract:
Climate sciences obtain forecasts like that of the global mean temperature from complex simulation models. How certain (or uncertain) are these predictions? A particularly intriguing problem is posed in this context by the plurality of models used that lead to a plurality of forecasts. Thus, a recent debate in climatology asks: Will ongoing modeling progress lead to a convergence of the models and forecasts? But also: Does an assessment of predictive uncertainty require convergence?
In my talk, I will argue that the validation of climate models faces a problem that is of general significance for complex simulation models. This problem -- a kind of confirmational holism -- arises when the interaction of components (sub-models, parameterizations, and kludges) is crucial for bringing about the overall dynamics while, at the same time, preventing analytic understanding. Such an understanding would allow us to attribute particular features of the global simulated dynamics to particular modeling assumptions. In other words, confirmational holism makes it hard (or impossible) to single out the culprits that cause the existing plurality of climate models with their respective range of predictions. It is not likely, therefore, that further modeling efforts lead to unification. Thus, the question arises whether the quest for an overall assessment of uncertainty is paramount to hunting a chimera.
(The argument will be based on a paper co-authored with Eric Winsberg.)
Bio:
Johannes Lenhard studied philosophy and mathematics at the universities of Heidelberg and Frankfurt (Germany) where he finished his dissertation in mathematics. He is affiliated with the philosophy department at Bielefeld University and spends the academic year 2009/2010 as research associate professor at the University of South Carolina, Columbia, supported by the NSF and Humboldt Foundation. A main focus of his research interests in the philosophy of science is on applied mathematics, most recently on computer simulation.
