Short of launching all the nukes, it's actually really hard to imagine a faster way to make Earth uninhabitable than humanity's GHG emissions project. (3.68×10^13 kg of CO2 in 2022 alone! Impressive!)

If we could terraform planets as quickly as we're de-terraforming Earth, Mars would be prime real estate in no time. Alas.

> hard to imagine a faster way to make Earth uninhabitable

Manufacturing lots of SF6 (sulphur hexafluoride) might do the trick. 22800x more greenhouse potential than CO2 per unit mass.

It's way more dense[0] than air, though, so not a lot of it reaches the upper atmosphere. I don't think it's 22800x more effective when produced at ground level.

[0] https://www.youtube.com/watch?v=u19QfJWI1oQ

That's why we're aiming for in-orbit manufacturing, isn't it?