When politicians talk of climate “uncertainty,” they’re often casting doubt on things that are well understood: Warming is happening, and humans are responsible. When scientists talk about climate uncertainty, they’re usually talking about the clouds. Clouds are tricky because they do two things at once. All that puffy whiteness blocks solar energy from reaching the ground, bouncing it back to space, which provides a net cooling effect. But clouds also act like a blanket, capping and trapping heat in the lower troposphere, which is where people who aren’t on the International Space Station live. That ambiguity makes it difficult to simulate with desirable precision how much and how fast the planet is warming, leaving a big mystery floating lazily over our heads. Some of that uncertainty was lifted Monday, and the news isn’t good. A new study in Nature analyzes almost 30 years of weather observations to show that […]