we’d have to drag some real big rocks out of orbit into the planet to glass it. not sure we ever had enough nukes even in the heyday of bomb production to actually glass the planet. we could cooperate to distribute the strikes uniformly but even then we wouldn’t glass the planet.

now, humanity might go with such a coordinated program, but the planet will burp, continue to undergo geological changes, and a few million years later there would be hyperintelligent octopi or capybara driving around.

but a nice rock, say, about the size of rhode island, that might do it. especially if it’s coming at a good clip.