Climate change is real, case closed. But there's still a lot we don't understand about it -- and the more we know, the better chance we have to slow it down. One still-unknown factor: How might clouds play a part? They already play a critical role in regulating earth's temperature, and they may buy us some more time to fix things. Climate scientist Kate Marvel takes us through the science of clouds and what it might take for the earth to break its own fever.