Talk Abstract:
Climate scientists like to use blackbodies and the Stefan-Boltzmann law to reason about Earth's energy balance. Since the Stefan-Boltzmann law scales as T^4, Earth's outgoing longwave radiation (OLR) should be a non-linear function of surface temperature. Observations and numerical models show, however, that Earth's OLR is essentially linear in temperature. In this talk, I will argue that careful thinking about when and why Earth's OLR is linear doesn't just help us understand a fundamental feature of Earth's climate, it also helps us resolve a number of related puzzles such as: what sets the magnitude of Earth's climate feedback; how can imperfect and biased global climate models still largely agree on the magnitude of Earth's clearsky feedback; and what does this tell us about the state-dependence of Earth's climate sensitivity?