Great rationality posts in the OB archives

lukeprog

I'll tell you: it was the villains of our story (okay not really, that's actually for-profit media)... the glaciologists! Yes! You see, Cesare Emiliani was famous because he helped discover that ice ages are cyclic phenomena, a huge advance in paleoclimatology, before that was even a thing. And it turns out, we're just about due for our next ice age!

Ice ages are not cyclical, but glaciations are. We are currently in an ice age, but in an interglacial period within that ice age. We may be "overdue" for the next glaciation, but it is also possible that the last glaciation of this ice age has already occurred, and we are heading back into a warm earth era typical of the overwhelming majority of the planet's history.

Thanks for pointing out this terminological issue. I'm going to keep calling glaciations "ice ages," just because that's how they were labeled to the public in the 1970s, viz. the title of Emiliani's 1978 paper The cause of the ice ages, or, of course "The Weather Conspiracy: The Coming of the New Ice Age." :)

2garethrees13y

The paper * David Archer & Andrey Ganopolski (2005), "A movable trigger: Fossil fuel CO2 and the onset of the next glaciation", Geochemistry Geophysics Geosystems 6:5. provides evidence that periods of glaciation begin when northern hemisphere insolation (which varies due to changes in the precession, obliquity and eccentricity of Earth's orbit) falls below a "trigger" level that depends on the amount of CO2 in the atmosphere. Archer & Ganopolski suggest that we're currently approaching a solar minimum, but we've already released enough CO2 into the atmosphere to avoid a glaciation in the next few thousand years. (If we burn all available fossil fuels, "The model predicts the end of the glacial cycles, with stability of the interglacial for at least the next half million years".)

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Great rationality posts in the OB archives

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Great rationality posts in the OB archives

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