Life has adapted to the current climate. ANY change will mean winners and losers. I'm pretty sure the losers will outweigh the winners.
Yep, lots of human losers already, but why worry about them

Five inches of rain today.. What costly AGW effects?
Did you know too little atmospheric CO2 is what causes our ice ages? Ding "explains"!
Yeah, it can average two hundred degrees worldwide, no problem!
But don't you dare let them pesky ppms drop too low at the poles or.. look out!..
Game over, man! Game over!