In the North, we all know about the Ice Age. We generally agree that about 2 million years ago we started the Pleistocene Epoch. I'm not totally convinced that the day before this was all sunshine and roses, since subsequent glaciations would have removed all evidence. I'm fairly convinced this is tied in with Plate Tectonics and big earthquakes, since that is what I do. :)
So, at 60 million years ago, we were still warm enough to have a few dinosaurs roaming around, and then everything got colder as the continents separated. Remember that at 150 million years ago, the continents were having a big party, and tons of CO2 and water vapour were being baked out by the thermal insulation.
So, if you want to talk about Climate Change, look at the temperature change from the Mesozoic to now. Straight down the tubes, baby. If we raised a dinosaur now, it would want to go right back into its egg!
So, you wouldn't have noticed a big change on Day 1 of the Pleistocene. We do know that our wonderful Trade Wind System had a shit-fit. It actually reversed and died. This killed the Gulf Stream, which is the only thing that keeps us and Europe talking. The North had nothing better to do than freeze up. What caused the cycles?
As I've stated, the Friendly God belief is thus: There is no unstable earth process that will wipe us out. Everything has a balance.
Now the hard-core, no God version: The Universe is controlled by Blind Chance. There are no unstable processes that will wipe us out, because they would have been triggered in the past, thus rendering things moot. A little shift in the Cosmic Dice, and we wouldn't be here, like millions of other planets.
But really, everything we see now has been triggered in the past. So, the Ice Age Advance has a balancing force, or we'd all be under ice, and Google wouldn't be sinking barges. :) To me, the main force is Isostatic Response, which sinks all the continents under kilometres of ice, below sea level. Try to build up ice cubes with that! Once the ocean level goes super-high, the Trade Winds start up their happiness.
I'm not extrapolating any more, but the continents are still down, and we've got a while to go in this inter-glacial. As with the others, we can expect Florida weather in Toronto, but not in my lifetime (rats). So, take all this 'New Ice Age' talk with a Scotch on the Rocks. :)