I've already suggested in another thread that any 'solution' to global warming that doesn't involve mass genocide will be too slow to have any effect.

Even sterilization might not be quick enough.

Obviously, neither is acceptable from a humanist perspective.

Actually, now that I've read your comment closer, I noticed you mentioned serialization. Do you mean digitizing people's minds and killing them afterwards?

For a start, the cities you list contain many valuable people. Places doing lots of slash-and-burn farming, not so much. My original comment was a bit facetious, but if it is a civilization-ending threat (and I'm not saying it is), better to start the killing sooner when we can control who dies than collapse the whole thing and lose thousands of years of scientific and cultural progress.