Complementary observational constraints on climate sensitivity
Article first published online: 25 FEB 2009
Copyright 2009 by the American Geophysical Union.
Geophysical Research Letters
Volume 36, Issue 4, February 2009
How to Cite
2009), Complementary observational constraints on climate sensitivity, Geophys. Res. Lett., 36, L04708, doi:10.1029/2008GL036457., and (
- Issue published online: 25 FEB 2009
- Article first published online: 25 FEB 2009
- Manuscript Accepted: 6 JAN 2009
- Manuscript Revised: 24 DEC 2008
- Manuscript Received: 24 OCT 2008
 A persistent feature of empirical climate sensitivity estimates is their heavy tailed probability distribution indicating a sizeable probability of high sensitivities. Previous studies make general claims that this upper heavy tail is an unavoidable feature of (i) the Earth system, or of (ii) limitations in our observational capabilities. Here we show that reducing the uncertainty about (i) oceanic heat uptake and (ii) aerosol climate forcing can—in principle—cut off this heavy upper tail of climate sensitivity estimates. Observations of oceanic heat uptake result in a negatively correlated joint likelihood function of climate sensitivity and ocean vertical diffusivity. This correlation is opposite to the positive correlation resulting from observations of surface air temperatures. As a result, the two observational constraints can rule out complementary regions in the climate sensitivity-vertical diffusivity space, and cut off the heavy upper tail of the marginal climate sensitivity estimate.