Today's Proceeding of the (US) National Academy of Science has an interesti ng paper.
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The Dansgaard?Oeschger cycles happened every 1470 years during the last ice age
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John Larkin claims that climate is chaotic and thus unpredictable, but limi t cycles in a chaotic system can be remarkably regular, and comprehensible.
The link is to the abstract. I should be able to get hold of the full paper if I ask the right people.