What could cause my millennium-long ice ages?

Here on earth, it takes about 90,000 years for major ice sheets to build up, and another 10,000 for them to collapse, resulting in 100,000 year cycles of major glaciation, from what I understand.

Would it be too far fetched to imagine a world where this happens at a much faster and more regular rate, e.g. every thousand years? Could my explanation for this phenomenon be as simple as a periodic gravitational tug from another large planet? And what about extreme glaciation, where the ice sheets extend so far from the poles that only the equator remains uncovered? Would there be enough time for that to happen?

I understand that ice sheets form when summer temperatures don't rise above freezing (due to orbital eccentricities, changes in ocean currents, etc.) and snow continues to accumulate and compress year-round. But I don't have any sense of how long my scenario would take to unfurl.

Thanks in advance for any pointers!

posted over 4 years ago

HolocronCollector‭

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