EARTH In the literature: partially resolved

Can paleoclimate evidence rule out climate sensitivity above 5 K?

In plain words

Several recent climate models warm by more than 5 degrees for doubled CO2. Past climates such as the last ice age may show this is too much.

Precise statement

Determine whether combined constraints from the Last Glacial Maximum, the mid-Pliocene, the early Eocene and the historical record exclude $\mathrm{ECS} > 5\ \mathrm{K}$ at the 95 percent level, accounting for state dependence of feedbacks and forcing uncertainties. An answer is a posterior probability for $\mathrm{ECS} > 5\ \mathrm{K}$ with stated assumptions.

What would settle it

Bayesian synthesis of paleoclimate proxies and model emergent constraints with explicit state-dependence and structural uncertainty.

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