Abstract.
Earth’s albedo (reflectivity) declined over the 25 years of precise satellite data, with the decline so large that this change must be mainly reduced reflection of sunlight by clouds. Part of the cloud change is caused by reduction of human-made atmospheric aerosols, which act as condensation nuclei for cloud formation, but most of the cloud change is cloud feedback that occurs with global warming. The observed albedo change proves that clouds provide a large, amplifying, climate feedback. This large cloud feedback confirms high climate sensitivity, consistent with paleoclimate data and with the rate of global warming in the past century.
This is pretty much the worst possible news. It is not entirely intuitive, I was hoping that higher temperatures would accelerate evaporation possibly increasing cloud cover, potentially at higher altitudes (as the proper temperature for cloud formation got further from the surface). This data shows that is not happening.
The bonus news is that all of those IPCC models about how much emissions we can have assume a low sensitivity. Not that we as a species have had any success in curtailing our headlong rush to reach those overly optimistic limits.
Expect more “models didn’t predict this climate failure to happen so soon” headlines.