Simulated Volcanic Winter. Just like what they used to model nuclear winter.
Fuck talking about asteroids, Volcanic Winter scares the shit out of me and happens every few hundred years. We need to be teaching this in school in American History so that people understand why they need to learn how to use a pressure canner to store some food.
Also, all those green energy solar panels won't be worth a shit with an obscured sky, so let's get Thorium salt reactors online. About 40 years overdue for that tech.