Radiation, Convection, and Climate

The 2021 Nobel Prize in Physics was awarded in part to climate scientist Syukuro Manabe, largely due to his early and accurate estimate of Earth’s climate sensitivity to increasing CO2. This estimate relied on a proper coupling of radiation and convection - the two avenues by which energy flows through Earth’s atmosphere. This talk will explore further consequences of this coupling. Firstly, global mean rainfall is actually constrained by greenhouse gas radiation to increase with surface warming, at a rate of roughly 2-3% per K. Combining this with Clausius-Clapeyron scaling of water vapor concentrations then shows that the frequency of convection must decrease with global warming, at a rate of roughly 3-5% per K, with consequences for the intensity distribution of rainfall. These results are explained with chalkboard physics and verified with computer simulations, using a hierarchy of numerical models including today’s state-of-the-art climate models.

Speaker: Nadir Jeevanjee, NOAA