Kip Hansen is so peeved at the New York Times for their recent article about global warming accelerating, that he posts at WUWT denying any and all acceleration claimed in the article. His “rebuttal” is riddled with mistakes and falsehoods, par for the course at WUWT.
One of the things accelerating which the Times article mentions and Kip Hansen denies, is sea level rise. Let’s look at his approach to sea level rise acceleration, in order to find out how this climate denier manages to deny the undeniable.
First he mentions the research of Nerem et al. establishing acceleration in sea level during the satellite era (since 1993), only to dismiss it
First into the breach in defense of scary sea level rise is Nerem et al. (2018) which manages to transmogrify satellite altimetry data from the TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 missions into a claimed annual SLR of “4.5 millimeters a year”. NOAA apparently failed to get the message:
Then he shows us a graph (from NOAA/STAR, of sea level according to satellite observations) and says this:
Trend in Global Ocean Mean Sea Level? 2.9 (+/- 0.4) mm/year which they represent, quite correctly, as a perfectly straight line since 1993.
When Kip Hansen declares (about the trend,) that “they [NOAA] represent, quite correctly, as a perfectly straight line since 1993,” he makes it sound like NOAA has endorsed his claim, which is absolutely false. NOAA makes it clear: the straight line is there to show what the best-fit straight line is and report its slope. Any endorsement of the idea that’s all there is to the trend, is in Kip Hansen’s imagination only.
Notice: he has said nothing of any substance about the methods or results of Nerem et al., but somehow he thinks he has refuted them.
Notice: he has said nothing of any substance about the presence or absence of acceleration in the data he points to himself. The fact that NOAA calculates and plots a best-fit straight line, says nothing (of substance or not) about whether that’s the whole trend. NOAA never claimed it did.
So, nothing of substance! Except … he points us to his source:
If any readers are in doubt about this data, NOAA STAR NESDIS makes all the data available starting from this page.
I’m not in doubt about the data, but I am in doubt about Kip Hansen’s claims. So I followed his link and downloaded the data referred to (“slr_sla_gbl_free_all_66.csv”). And here it is:
The data in the file are not identical to the data plotted by NOAA. I suspect that the plots from NOAA apply a 60-day smooth, because the data themselves show a 60-day periodicity due to the orbit of the satellite itself, which is best removed to portray sea level trends. I’ll work with the data as is.
Computing the mean sea level at all times (averaging over satellites active at the time) I get this:
The solid red line is the best-fit straight line; it is not an endorsement of the idea that the trend is a perfectly straight line. I also computed yearly averages, just to reduce the noise level and give a clearer picture of what the trend might be:
Does it look to you like the trend is a perfectly straight line?
I know, “looks like” is not proper scientific evidence.
Let’s apply some statistics. Step one: if the real trend is a perfectly straight line, then when we subtract that straight line from the data, what’s left (the “residuals”) will show no trend at all (unless you call “flatline” a trend). Let’s take our best-fit straight line (by least squares regression), subtract it from the data itself, and see what residuals remain:
The gray line is the residuals, the big blue dots are yearly averages of same. Does it look like there’s no trend, just “flatline”?
I know … “looks like” is not proper scientific evidence. But that’s a helluva “looks like.” Bring on the statistical tests.
I tried a linear spline, a trend model made of two straight lines which meet at their endpoints (the “breakpoint” or “knot”). I chose the timing for the knot by changepoint analysis, and that gives me a test of statistical significance (which includes the effect of selection bias). Result? The p-value, less than 0.0001, confirms there is some trend other than just a single straight line.
I also fit a quadratic trend to the data. This is not an endorsement of the idea that the trend is a perfect quadratic, but if the quadratic term is statistically significant it does enable us to reject the idea of nothing but a straight line. The p-value, again less than 0.0001, confirms that there is some trend other than just a straight line.
I also fit a lowess smooth and a linear spline to the residuals, and here they are one more time with the lowess smooth in red (pink band for its uncertainty range) and the linear spline in brown (dashed lines for its uncertainty range):
This displays what the statistical test confirm: that there is some trend other than just a straight line. In fact, the rate of sea level rise got faster. We call that “acceleration.”
Notice: Kip Hansen did none of this.
I used both the lowess smooth and the aforementioned linear spline to estimate the rate of sea level rise. For the linear spline, the results (and their uncertainties) are the average rates during the linear intervals. Here’s the result, in red for the lowess smooth (its uncertainty range in pink) and blue for the linear spline (dashed lines for its uncertainty range):
The NOAA/STAR data, which Kip Hansen himself pointed to, are perfectly consistent with the claim that sea level rise is currently at 4.5 mm/yr.
Notice: The data Kip Hansen points to, outright contradict his own claim of “perfectly straight line” They don’t contradict, but actually support the results of Nerem at all.
My opinion: this is at least in part because he didn’t study the data he refers to and certainly didn’t “thoroughly check” anything. Which is ironic, given his closing comment (emphasis his):
Every time a person takes in something that is not true and accepts it, they become effectively stupider. Promulgating false information, intentionally, through failure to thoroughly check its validity or through failure to label something properly as opinion, is a crime against the collective human mind.
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