I certainly don't know the answer to that - but there are several reasons to be thinking that we would be FAR FAR better off if we launched a concerted effort on this a decade ago......
The slower the change comes the better off the inhabitants will be and the more chance they can get out of the way of the looming storms, floods, fires etc
Yet, there is no plan. At least not one on a Global scale that would actually matter (giant scale/right now).
Sounds like we're f'd no matter what.