Except many won't find they gained good farmland if they don't have it already. They'll still have poorer colder region soils with new higher temperatures. Getting the perfect temperatures to grow new crops won't fix marginal and often thin soil. Chances are the worms, microbes and fungi won't be right for the new conditions either.

That would take ages to resolve naturally, or if we know how to shortcut, lots of coordinated effort - and no doubt yet more emissions.