Many clues have been revealed as to the state of global warming in Year Zero.
- Baseball in February: The posts on Another Version of the Truth's forum relating to Angry Sniper's attack on Wrigley Field indicate it occurs in early February, 0000. This, and with the play-by-play announcer's comment on "a beautiful spring day" indicate that the Major League Baseball season has been shifted so that playoffs are in spring.
- A message intercepted in The Mailstrom, advertising Green Bay, Wisconson as a Spring Break destination. It mentions that Florida has become sunken (probably due to rising ocean levels), and that the South is "Hotter than a breakfast skillet".1
- Another message intercepted by The Mailstrom, advertising an oppertunity to hunt the last surviving Black Bear.