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Complementary observational constraints on climate sensitivity
Author(s) -
Urban Nathan M.,
Keller Klaus
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl036457
Subject(s) - climate sensitivity , sensitivity (control systems) , climatology , forcing (mathematics) , climate model , environmental science , atmospheric sciences , climate change , geology , oceanography , electronic engineering , engineering
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.