There was an article in
The New Yorker a few months back about the efforts focused on drilling/reading the historic ice. At least one team has been bringing up rods of ice from the ice caps, which accumulate annually, and using them to try to guage historic atmospheric conditions. Among the interesting things in the ice are things like smoke from Mt Vesuvius.
Anyways, there appears to be a pattern of 90,000 years Ice Age, 10,000 years warmth. And apparently, we're at the end of the 10,000 years warmth. There's even some speculation (in this article) that Global Warming may in fact be keeping us
away from an Ice Age.
It's probably just another theory in a field
full of them. But it is an interesting alternate view on the big GW (global warming, not the president seeking to augment it).