Just the same things everyone else has worked out. But since I'm not sure you're as smart as everyone else: we're in the same boat as a lot of different people, time-travel wise, and some alternate future versions of us were already here. Since we didn't plan ahead for it (by which I mean, I didn't plan ahead for it) that would imply that our "future" uses aren't from the same universe that we are--otherwise they would have remembered being here before and we wouldn't have been caught in the cold.