What caused the ice ages?
The question is complex, and I do not believe that we have an answer for this any more than we do for Global Warming.
In the geologic rock column there are precambrian rocks that are glacial rock deposits. So that means we've had glacial cycles for a very long time.
To look at today's earth and try to give an explaination for the Pleistocene glaciation which started 2.5 million years ago probably would not explain them all.
For instance, the placement of the continents today controls ocean currents, winds, and overal global temperature. If the continents were in one mass like they were with Pangea, or partially together like Gwondwanaland it creates a whole new dynamic of climate behavior, something the global warming clowns do not even discuss in their current doom and gloom wet dreams.
Since continental drift takes millions of years, it can be expected that our current situation has been and will continue to be dominated by our current continental configuration. Disruption of the Trans Atlantic Conveyor current by melting glacial ice could well plunge us into another deep freeze of glacial ice long before the world heats up like it has in the past, when massive continents controlled the global climate. Imagine a single contient situated along the equator where it baked in the sun heating up the atmosphere and one gigantic ocean that soaked up the heat part of the day but did not release it as quick as the land. Would the earth be hotter or have less temperature spikes?
So you see past global climate change is a lot more complex than just saying that man did it by burning fossil fuels for the last 117 years. In reality that 117 years is not even a millisecond on 24 hour geological clock. Our current cool spell has lasted 2.5 MILLION years. Not a thousand, not ten thousand, not 100,000 thousand but twenty five times longer than that. 117 years is nothing. Anyone who thinks they can make projections based on what amounts to less than a single data point is trying to sell something, or at least trying to make money or a name for themselves by peddling bullshit.