If the climate can no longer support barley, hops, and other beer-centric grains, you're screwed.

One of the great things about Humankind, however, is discovering new and interesting ways to get messed up. You can make wine or distilled spirits out of just about anything given the time and motivation. I hope it does not get so drastic that you will have to get used to cow-pie liqueur, but I'm guessing it will still mess you up!!