claim: The Schmittner et al. study finds low probability of both very low and very high climate sensitivities, and its lower estimate (as compared to the IPCC) is based on a new temperature reconstruction of the Last Glacial Maximum that may or may not withstand the test of time.
evidence: Orbital forcing from cycles in the earth's orbit around the sun has, for the past 2,000 years, caused a long-term northern hemisphere cooling trend that continued through the Middle Ages and the Little Ice Age.