How one controversial startup hopes to cool the planet

Stardust Solutions believes that it can solve climate change—for a price.

The Israel-based geoengineering startup has said it expects  nations will soon pay it more than a billion dollars a year to launch specially equipped aircraft into the stratosphere. Once they’ve reached the necessary altitude, those planes will disperse particles engineered to reflect away enough sunlight to cool down the planet, purportedly without causing environmental side effects. 

The proprietary...