Complementary observational constraints on climate sensitivity

Nathan M. Urban, Klaus Keller

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


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.

Original languageEnglish (US)
Article numberL04708
JournalGeophysical Research Letters
Issue number4
StatePublished - Feb 28 2009

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


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