At that time, if things don't improve by a huge margin (like in : never before in human history; except maybe at WW2 levels), hundreds of millions of people will have moved away from their birthplace (taking the place of other who may or may not be happy with it, which may lead to "tension" between populations; see what happens today when a few refugees (yes, a few) reach the borders of Europe...)

My understanding is there will be many more losers than winners.

Then I would kindly suggest governments stop encouraging people to continue reproducing at an unsustainable rate. Reversing overpopulation would make both mitigation and adaptation much more feasible.

Not requiring ones next generation to be precisely from local genetic stock is a good start. Being able to absorb refugees into ones culture vs crying on and on about low domestic birth rates, that’s a pet peeve of mine