Global Warming - Let’s talk sea levels
I’m not sure what to make of the global warming debate. With the release of algore’s “Inconvenient Truths,” the discussion is front-and-center again. On the one side the many scientists and politicians who warn that human activites (CO2 emissions, for example) have added to global warming, that it is worsening, and that we must take steps to alleviate it; these are the “advocates.” On the other side — the skeptics, the rebutters.
The complex forecasting models used are beyond my understanding. About the only way for me to make sense of this debate is to look at the competing claims of the different sides, and see which seems more compelling, more objective.
The two sides must necessarily take different approaches. The advocates will roll out a ton of data models and scientific consensus, and assuming the citizenry’s trust in a non-conspiratorial science establishment, seek to persuade with efforts like “Inconvenient Truths.” The skeptic/rebutters must take a different tack; they must pick out ten of the advocates’ 100 arguments and show that these ten are flawed.
Like the parents of small children, the skeptics “choose their battles.” In effect, they don’t have to argue the other ninety points. If they pick ten points, and demolish them, then that is very persuasive. But, and this is important, they must be very, very persuasive and objective on their ten chosen points. If they accuse the advocates of cherry-picking, selectivity, or other errors, the rebuttals (on the ten selected points) must not include the same flaws.
In this article from TCS Daily - Inconvenient Truths Indeed, Robert Balling does about what I have described. He goes after six points. The one about historical sea levels was quoted in Powerline, and attracted my attention. Unlike forecast models, historical sea levels would seem to be more easily determined, less subject to interpretation.
Gore claims that sea level rise could drown the Pacific islands, Florida, major cities the world over, and the 9/11 Memorial in New York City. No mention is made of the fact that sea level has been rising at a rate of 1.8 mm per year for the past 8,000 years; the IPCC notes that “No significant acceleration in the rate of sea level rise during the 20th century has been detected.”
That is interesting. Sea levels have been rising at a rate of 1.8 mm per year for the past 8,000 years. If you’re like me, you would assume that that’s a representative, unbiased, “straight-shooter” kind of a number, right? It’s algore and the lefty scientist advocates and scare-mongers who are cherry-picking and so forth, right?
Hmmm. Look at this chart of Holocene sea levels:
Oh. Sea levels rose rapidly 8,000 - 7,000 years ago, but for the past 7,000 years have flattened out. That “1.8mm per year” is like drawing a straight diagonal line on this graph. Not a lie, but not exactly representative of the data. If sea levels began rising at 1.8mm per year over the next decade, would that be “business as usual,” or a historic change?
BTW, the forecasts are for sea levels to rise by 50cm to 1 meter in the next century, somewhat more than double the increase of the 20th century.
I looked a little more. 8,000 years isn’t very long. What about over longer time frames?
Same story. Since the glaciers melted about 18,000 years ago, sea levels rose, and have flattened out for the past 7,000 years.
Now I’m beginning to understand that sentence: “No significant acceleration in the rate of sea level rise during the 20th century has been detected.” And here’s the chart of the past century:
I don’t know what to make of that little red bit at the end. But here is a baseline. We have good data going back to 1880. Let’s see if it trends up in the coming years.
One more chart, going way back, over 800,000 years ago.
It looks like sea levels have fluctuated a lot over the past 800,000 years. And, we are at an all-time high right now. I’m getting on thin ice here, but if we are at an all-time high, shouldn’t ocean levels be trending down? Is “no significant acceleration in the rate of sea level rise” a comforting trend? In any case, in a discussion of historical sea levels (however brief), the fact that they are at a million-year high is noteworthy.
I’m still not sure what to make of it. But the skeptic Balling didn’t cover himself in impartial, objective glory on the battleground of his choice - historical sea level data.
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