ESRL/PSD Seminar Series

Abstract

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Pretty much everything we have any confidence in when it comes to climate change is related to global patterns of surface temperature, which are primarily controlled by energetic and thermodynamic aspects of climate. In contrast, we have much less confidence in circulation aspects of climate change, which are primarily controlled by dynamics. Yet circulation exerts a strong control on regional aspects of climate, including chaotic variability on multi-decadal timescales. As scientific interest shifts from detection and attribution of climate change to prediction of its effects at the regional scale, uncertainties in circulation will become an increasingly important aspect of the uncertainty associated with climate change.

Model predictions of the atmospheric circulation response to climate change are in many cases highly uncertain, presumably because of systematic errors in the climate models (e.g. the location of the jet stream). The fact that these errors have stubbornly persisted despite increases in spatial resolution suggests that they are somehow linked to unresolved processes, whose effects need to be parameterized in the models. There are good reasons to believe that model bias, the divergence of model projections, and chaotic variability are somehow related. This talk will present some examples of these kinds of uncertainties and some potential ways forward, in terms of both the science and the communication of these uncertainties to the public.

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