From John Timmer at Ars Technica:
Somewhere around a million years ago, the climate underwent a transition. Earlier, it was going through glacial cycles every 40,000 years, but it shifted to taking 100,000 years to cycle (this shift is termed the mid-Pleistocene transition).
Snyder’s new record shows that the planet was getting slowly but progressively colder for the first million years or so. But by 1.2 million years ago, the cooling trend began to slow down. After it flattened out, the overall global average temperature has remained stable through to the present, even as glacial cycles caused lots of fluctuations around that average.
The analysis can’t separate cause and effect, so there are a number of possibilities here. One is simply that some external cause changed both the overall trend and the length of the glacial cycles. It’s possible, however, that it simply became too cold for the 40,000 year cycle to register.
If the paper had stopped there, everyone seems to agree that it would have been a valuable contribution to the field. But Snyder went on to analyze how global temperatures compared to atmospheric levels of carbon dioxide over that period, using that to calculate what she termed the climate’s sensitivity to greenhouse gasses. More.
That’s her mistake if whatever she wrote doesn’t front the needed narrative.
Anyway, live easier. Most a-crock-a-lypses are science fiction. Real life just isn’t that interesting. You have to go to work and come home again.
See also: Federalists, the Pope, and climate change
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