A new study indicates that stable cloud layers, which reflect sunlight and help cool the Earth, are increasingly breaking apart due to climate change. Ulrike Lohmann, an atmospheric physicist at ETH Zurich, explains that this transition to cumulus clouds allows more sunlight to reach the surface, exacerbating global warming. While there are proposals for geoengineering methods to artificially enhance cloud formation, Lohmann cautions against private companies conducting such experiments without sufficient understanding of potential side effects.