Mark
CreativeMountainGames.com
I had a group of PCs who were elves in one campaign and we would jump a bunch of years in between adventurers. This was in an earlier edition and basically elves could live a natural life and never expire. In this game I had an ice age creeping up on them and they didn't put it all together for quite a while. I didn't leave them any options for stopping it so the best they could do was help the world prepare for it.