A fleet of jets takes off from airports around the world. They ascend beyond the cruising altitude of commercial airlines until they reach the stratosphere. Then, they spray. A thick stream of sulfuric acid pours forth from the aircraft, bathing the skies in toxic aerosols. Winds spread the noxious cloud around the world, where it lingers for months, even years. The effects down on Earth are unmistakable. On every continent, blue skies are replaced with a pallid veil of white. The Milky Way disappears. There is less sunlight for solar power, more damage to the ozone, and a surge of droughts across southeastern Asia and central Africa.
Also, the Earth cools.
This scene is not an ongoing government conspiracy, or an unreleased prelude to The Matrix, or a diabolical plot by C. Montgomery Burns. It’s a plan that some of the world’s most sober climate experts have earnestly considered. It’s called solar geo-engineering, or, more euphemistically, solar-radiation management. And while we might be years from serious people screaming that it’s something we must do, some scientists today insist that it’s something we must research—in the bleak but plausible scenario that this is the emergency switch humanity will someday have to pull.