[MajorPo]

Originally Posted by Mohoender

As I like more natural (realistic settings), I picked three: Asteroid strikes, natural cataclysm and nuclear strike.

However, you can count that the three will occur more or less simultaneously. The supervolcano at Yellowstone unexpectedly blow up in an explosion equal to 2000+ time that of Mont St Helens. As two of the US missile base (if not three) are located nearby, the computers or men (communication cut) confuse that event for an attack and several missiles are launched toward Russia and China before this can be cancelled. Both countries also try to cancel their counter attack but they fail to do it before it's already too late and several missiles are launched toward US and Europe (A number of commanders, especially at sea, refuse to cancel the launching sequence and fire their missiles). This remain a limited exchange but a serious one nonetheless.

As a result, most capitals and several large cities in the northern emisphere are blown up, while 70% of the US are covered with ashes. Also when the erruption ends (4 or 5 weeks after it started), a nuclear winter is affecting the northern emisphere. The nuclear exchanges destroyed the various coordination agencies and casualties are high. They are especially dramatic in the US and in Canada. Nevertheless, the world slowly starts to organize and rerscue missions are taking place all over the northern emisphere, including Russian rescue team being deployed to the US. An emergency UN has been created at Geneva (Switzerland) and every country does its best to help. Rogue officers on all sides have been eliminated and surviving government officials are now collaborating to save what can be saved.

You know up to this point I think the long term effect would be extremely good for the worlds overall economic development and general sociopolitical outlook. The asteroids are pretty bad news. Of course I'm safely in the southern hemisphere which may influence my views