Chaotic dynamics have a pattern of periods of unpredictable disorder followed by bifurcations.
This cyclic pattern is often seen in intransitive systems. An almost-intransitive system displays some sort of average behaviour for a very long time, fluctuating within certain bounds. Then, for no apparent reason whatever, it shifts into a different sort of behaviour, still fluctuating but producing a different average. Yet it takes no great imagination for a climatologist to see that almost-intransitivity might well explain why the earth's climate has drifted in and out of long Ice Ages at mysterious, irregular intervals. If so, no physical cause need be found for the timing.