a murder trading scheme
Every legal jurisdiction has to allow a few deaths by violence, right? Especially when safety costs money.
So instead of having that be illegal, cap and trade.
(Like Jonathan Swift, but so much more sophisticated. We could even regulate it with a blockchain.)
More seriously:
The (!) problem with emissions trading schemes is that the things that people actually need to do if the climate is going to come under control are so far outside the Overton Window that, by the time people are ready to do them, it’ll be too late for an emissions trading scheme. (And, arguably, if they were, hypothetically, ready to do them now, we wouldn’t need an emissions trading scheme in the first place … although that depends on the details, whereas my point about the current Overton Window doesn’t.)
This is why it’s so obvious to anybody outside party politics that any emissions trading scheme (in the current political climate or anything remotely like it) is going to get completely gamed.