Date(s): April 15, 2008, 2:30pm

Location: Room 4144, EPA West

Presenter(s): Gerard Roe and Marcia Baker (University of Washington)

Description: Underlying all the benefit estimates of global climate change control are the climate's sensitivity to GHG increases; this presentation explored what is currently known about this critical factor.

What kind of information from the climate science community is the most useful for policy makers, and which uncertainties matter most? Constraining climate sensitivity - the long-term increase in global mean temperature expected from the doubling of atmospheric carbon dioxide - has been one of the main benchmark goals of climate science. I will review the various disagreements over what future progress might be anticipated, as well as the debate about the extent to which reducing climate sensitivity even matters for any practical decisions on climate policy.

Uncertainties in projections of future climate change have not lessened substantially in past decades. Both models and observations yield broad probability distributions for climate sensitivity, with small but finite probabilities of very large increases. We show that the shape of these probability distributions is an inevitable and general consequence of the nature of the climate system. Further, we show that the breadth of the distribution and, in particular, the probability of large temperature increases are relatively insensitive to decreases in uncertainties associated with the underlying climate processes.

Presentation Document: The Shape of Things to Come: Why is Climate Sensitivity So Unpredictable (and Who Cares Anyway)?

Seminar Category: Climate Science