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Atmospheric science
George Mason University
Events

3 Sep (CLIM) Tim DelSole, Climate Science

Sep 3, 2025, 1:30 - 2:30 PM

Speaker: Timothy DelSole, George Mason University 

Title: Are Climate Projections Credible?

Time: Wed, 3 Sep, 1:30pm 

Location: Horizon Hall, Room 4014 or via Zoom (for Zoom link, email xdu5@gmu.edu) 

Host: Xiaojing Du 

ABSTRACT: Climate models disagree on the magnitude of future warming, raising a central question: are climate projections credible? Traditional approaches to deriving observation-constrained projections—such as multi-model weighting, Bayesian frameworks, or emergent constraints—often produce consistent results, yet there are cases when all these methods fail, with no diagnostic to warn users in advance. In this talk, I use Energy Balance Models (EBMs) to construct scenarios in which traditional approaches to constrained projections break down. In particular, reproducing present-day climate statistics is neither necessary nor sufficient for accurate projections. Drawing on insights from these EBM experiments, I propose a new framework for observation-constrained projections that succeeds precisely in situations where conventional methods fail. Unfortunately, the method indicates that CMIP6 simulations do not meet the assumptions necessary for generating credible projections.

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