When was the last major ice age? I read that ice ages come in cycles and we're due for another one in about another couple thousand years. If these cycles take around 20,000 years to complete, that would make the last one about 18,000 years ago. Is this accurate?

You're correct about the last ice age's time, 18000 years ago (http://www.scotese.com/lastice.htm), but I doubt that the next ice age will be 2,000 years from now if the temperatures are rising so quickly.

Temperatures vary dramatically in "ice ages" for part of the time britain was home to lions and hippos(skeletons found under that square in London the name escapes me) other times it was wooly mammoths. all within a few thousand years.

gib65 - google Milankovitch cycles.

The recent group of ice ages, with their intergalcials have been greatly effected by three factors: the precession of the equinoxes; variations in the eccentricity of the Earth's orbit; changes in the magnitude of axial tilt. When the effects of these on incident solar energy are compared with data on global temperatures there is excellent corellation.

One long term disappointment of our current profligate use of fossil fuels is that they would have been very handy for burning by our ancestors in a few thousand years when the next ice advance was due.