Nuclear Holocaust

Mrdependable says:

"...and the idea of a nuclear winter is a myth."

Nuclear winter may or may not be serious, but it's certainly not a myth. There was a cooler summer and a colder winter worldwide after the Krakatau eruption in the 1880's, a three- or four-year "winter" after the Sumatra-Java splitter volcano in 535 AD, and geological evidence of a centuries-long winter after the Chicxulub Strike that ended the Crataceous.

Enough stratospheric dust for a single year could cool off the earth enough so that we will see extended year-round snow cover, which, in turn, will increase the Earth's albedo significantly, and... well, you can figure out the rest.

I certainly wouldn't blow off the concept of nuclear winter by any means.