Global Cloud Coverage Shifting in Ominous Sign of Climate Change
- Eric Roston
- Jul 18, 2016
- 1 min read
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 inNature analyzes almost 30 years of weather observations to show that clouds and cloudiness are changing in the way scientists would expect in a warming world. Continental storm tracks—think jet stream—are shifting poleward, leaving populous subtropical latitudes uncovered. And the clouds that are forming more often aren't the low-lying, reflective ones that cool the planet—they're the huge cottony anvils that rise high in the sky, trapping more heat.
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