Heck, this planet has been a hell of a lot colder and a hell of a lot hotter in the past few hundred thousands years (which is a nanosecond in the context of several hundred million years). Five hundred years ago, when Juan Cabrillo explored the California coast, there was snow all the way down to the waterline on the Big Sur, south of Monterey. If -- no, make that WHEN -- it gets that cold again, it's going to dramatically change food production in the U.S. because the way things are right now climate wise, California grows enough food year-round to feed a whole lotta folks
because the climate is right for it. Obviously it hasn't always been that way (see Cabrillo) and obviously, it won't always be that way.
GOD calls the shots on the climate on our old earth. We're just along for the ride.