THE QUESTION in so many ways IMO. But also, for me at least, it misses the point.
For me, so much is about the social. Like, I would have a hard time sacrificing a lot to save humanity from the climate crisis if I knew humanity wouldn’t know that they were saved (they don’t have to know it was me) but just figured the climate problem simply disappeared without learning to manage their problems.
Otherwise, personally, the basic sacrifice that is a no-brainer is to lead a simple, unassuming and arguably (from a materialistic standpoint) boring life. Regarding the climate crisis I’d say I’ve done that most of my life, which I don’t say with pride honestly as it’s about the only thing I’ve done.
Beyond that, if there’s some social buy-in from many to the relevant values etc, I think I’d certainly be willing to risk or end my life for the greater good.