The phrase “blocking out the sun” conjures up all manner of horrors, from the smoke and ash of a nuclear winter wiping us all out to Mr. Burns putting up a giant metal disc and plunging Springfield into darkness on
The Simpsons. But for a group of researchers at Harvard, it might hold the key to reversing the damage caused by climate change. Called the “Stratospheric Controlled Perturbation Experiment,” or “SCoPEx,” the project involves reflecting back UV rays from the sun by using a balloon dispensing a small cloud of chalk particles, about the same amount as a bag of bread flour, at high altitude over the Arctic Circle. It’s a small demonstration of the process of artificially altering the climate known as “geoengineering.”