Just a quick note, that when it comes to the heat that’s been building up in the oceans, Zeke Hausfather got right to the point:
He’s one of the authors of a new paper (Cheng et al. 2018) which brings together all that we’ve learned lately about ocean heat content, to show that the best estimate is going up faster than we thought before. In fact it’s following what the computer models predicted it would do, with surprising fidelity. You can find plenty of press reports, including in the New York Times.
The data in his graph (available here) are from Lijing Cheng, the paper’s lead author. They’re monthly data, and look like this (Hausfather’s graph uses a different baseline, doesn’t start until 1955, and shows a 12-month moving average rather than monthly values):
The rapid and seemingly inexorable rise in the heat of the oceans is a sign of trouble. If it continues, it will bring us another foot of sea level rise by 2100 from thermal expansion alone, quite apart from the melting of land ice. Since ocean heat is the energy source for storms like hurricanes, they can be even more destructive. Ocean species will have to migrate and adapt to the new conditions; they’re already on the move (ask fishermen), and their future is uncertain. That means our future is uncertain.
What strikes me most about the data is the sharp turn about 1990. It’s easily confirmed statistically, and if we model the data as two straight lines, choosing the optimal “turning point” by change point analysis, we get this:
With it, we can estimate the average rates during the two episodes, pre- and post-1990. Two things strike me about this. First, the increase in the speed of ocean heat content rise is quite large, going from 2.8 ZJ/yr to 9.5 ZJ/yr, three and a half times as fast. Second, it’s probably not a coincidence that the year 1990 is the same at which sea level accelerates. Since thermal expansion is one of the root causes of sea level rise, this is to be expected.
In closing, I’ll mention that my wife’s idea of “sea heat” is Jason Momoa.
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