Younger Dryas (Score 1)

This article doesn't seem to address what I have been told was the actual greatest danger of global warming, a Northern Hemisphere Ice age.

Popularized by The Day After Tomorrow, the science behind the northern hemisphere entering a mini ice age as a response to large amounts of fresh water melting into the North Atlantic, from ice sheets such as Greenland, is quite sound. I believe it is the leading theory as to what caused The Younger Dryas.

The basic principle rests on the fact that the North Atlantic Deep Water Current, which brings warmth to the Northern Hemisphere, relies heavily on the salinity of the ocean water. Making the water too fresh, as in from melting all the ice, would stop the current and cause a mini ice age. My understanding is that from the time this current is shut down to when the higher latitudes are uninhabitable is thought to be less than half a century.