Only becomes viable if you have things like Starship online and fully operational, with launch rates at the level of Falcon 9 today. At the minimum.

Still a more viable option than bringing greenhouse gas emissions into the negatives globally, by the way. But that's a low bar. Nuking the ocean floor is probably a better call.

I'm confident that pushing everyone involved with Starship into the ocean would be a better and faster and more ethical green transition.