[dread78645]

Is a feedback mechanism at work in earth's climate system that causes these cycles? Some like to point to possible variability of the sun [very common among stars] as the cause, others hypothesize some cloud of interstellar dust that the solar system passes through periodically.

Yes there is a feedback loop. When snow and ice can accumulate, that'll reflect the Sun's energy back into space (albedo); a positive feedback towards lower temperatures. Vice versa, less snow & ice (more green vegetation) retains energy.

There's a known 26,000 year cycle of the precession of Earth's axis. Sediment cores indicate a 41,000 year cycle of unknown cause. One hypothesis (that I subscribe to) is the 100,000 year cycle is a beat harmonic of those two cycles.

CO₂ is positively correlated with temperature. The argument is whether it's a leading (cause) or lagging (effect) indicator.

[RightWhale]

On the precession of the equinox, is there any reasonable explanation besides the wobble theory? Wobble seems more like an observation than an explanation.