Multiscale processes and instabilities in Earth's clouds: Why we must and how we can make progress in modeling them

How Earth's low clouds respond to climate change is the most important unsolved problem in the physical climate sciences. It is the source of the largest uncertainties in climate projections. The reason is the multiscale nature of clouds: scales from the micrometers or droplet formation, to the meters of turbulent cloud dynamics, to the thousands of kilometers of large-scale atmospheric circulations are intricately coupled in clouds. Explicitly resolving this large a range of scales in numerical simulations will remain out of reach for the foreseeable future. Here I show that the interplay of radiative and dynamical processes can give rise to instabilitites in stratocumulus clouds, which have the potential to dramatically alter climate. Such instabilities are not captured by current climate models because they inadequately represent the multiscale physics of clouds. I lay out a blueprint for climate models that can overcome these difficulties and provide more accurate projections of climate changes.