If your estimates are true, focusing solely on GDP once again ignores the externality of the millions of people who will die or be displaced by climate change.

If your estimates are true, focusing solely on GDP once again ignores the externality of the millions of people who will die or be displaced by climate change. Saying "GDP will come out okay" is equivalent to saying "the rich will come out okay", which may well be true, and you may find that comforting. Other people, perhaps not so much.