No. The point is that weather will get weird. As the global climate warms, weather patterns will break out of their normal negative-feedback-enforced cycles. Freakish temperature streaks, extreme precipitation, drought, and irregular winds will make agriculture much more difficult and unreliable everywhere. For a fun preview of what we're in for, check out the events of 1315-22 in Europe (hint: it's commonly called "The Great Famine").
The best part is that even if other regions (for example, Canada) have warmer weather, that doesn't mean agriculture will be sustainable there. The topsoil in that part of Canada is thin and highly acidic. You're not going to be growing corn and wheat there no matter what the weather patterns become.