Michael Oppenheimer, Albert G. Milbank Professor of Geosciences and International Affairs, Woodrow Wilson School. Director, Center for Science Technology and Environmental Policy
Structural uncertainty in models presents a longstanding obstacle to estimating future sea level rise. The model-based range of projections is often used to characterize uncertainty. However, this approach is inadequate when applied to sea level rise due to the known deficiencies of ice sheet models in combination with the growing significance of the ice sheet contribution. In its Fifth Assessment Report, the IPCC extended uncertainty analysis for sea level rise by applying ad hoc expert judgments about the possible effect of such model deficiencies, an approach the IPCC has also used in assessing uncertainty for climate sensitivity. Oppenheimer and colleagues propose a new approach utilizing expert judgment that combines an experience-weighted version of formalized expert elicitation with probabilistic inversion of parameterized physical models.