The "just do it!" part is inspired by Stephenson, sure. I didn't realize before that that it's the kind of problem that you can actually just do, since there is

The "just do it!" part is inspired by Stephenson, sure. I didn't realize before that that it's the kind of problem that you can actually just do, since there isn't a locked door to the stratosphere :) But the idea itself is much older, and AFAICT very safe. The only thing missing is a practical way to get millions of tonnes of SO2 to the stratosphere aside from burning dirty oil on the ground. These guys are supposedly working on it: https://makesunsets.com/ https://makesunsets.com/