Sea Level Rise is NOT Accelerating

B Willis Eschenbach – Re-Blogged From

I had to go to town yesterday, and so I was glad it was Friday, because it’s Science Friday on the local Public Broadcasting System station and I can listen on my truck radio. In general I enjoy Science Friday, because the host, Ira Flatow, has interesting people on the show and he usually asks interesting questions … except when it’s about climate change. In that case his scientific training goes out the window, and he merely parrots the alarmist line.

In any case I was listening to Science Friday yesterday, and Ira referred to some recent pictures of flooding in Miami, Florida, as evidence that climate change is real and is already affecting Florida. It was the radio so no pictures, but he was referring to photos like this that have been in the news …

miami floodingHe was talking with a young woman, a Chicana climate activist. He and the activist agreed that this was clear evidence of anthropogenic climate change. In response to his question, she said that she was definitely using the Miami flooding to drive home the message that people should be very afraid of human-caused climate change, and that we’re already seeing the effects. I was depressed thinking of the fear, uncertainty, and doubt that such false claims would cause.

I fear that both of them have been taken in by what I call a “scientific urban legend”. It’s easy enough to do. It happened to me a lot a while back … not so much lately, my urban legend detector works pretty well these days.

In this case, the urban legend is the false claim that warming over the last century has accelerated the rate of sea level rise. There is no sign of this claimed acceleration.

From the beginning of the climate alarmism in the 1980s, the long-predicted acceleration in the rate of sea level rise has been … well … the kindest description might be “late to the party”, because the predicted acceleration still hasn’t arrived. James Hansen famously predicted back in 1988 that in forty years the West Side Highway in New York City would be underwater. From the 1988 levels, to swamp the West Side Highway would require about a 3 metre (10 foot) sea level rise.

We’re now 27 years into his prediction, two-thirds of the way there, and instead of two-thirds of three metres of sea level rise, the sea level rise in NYC since his prediction has been … wait for it …

Three inches. 7.5 cm.

And from this point to make his prediction come true, we’d need ~ 9.9 feet of sea level rise in 13 years … that’s three quarters of a foot (225 mm) each and every year for the next thirteen years. Never happen. His prediction, like the overwhelming majority of climate alarmist predictions, is total nonsense. Here’s the data, from the PSMSL.

tides new york battery psmslNote the lack of any evidence of acceleration in the New York record … but we were talking Florida, not New York. Unfortunately, the Miami record is short, truncated, and intermittent. There are records from the thirties to the fifties, then a five-year gap, then the record stops abruptly in the eighties, with the last few years missing data. As a result, it’s useless for looking at acceleration of sea level rise. However, there are a couple of long-term stations in the vicinity. Here are the two longest continuous tide station records in Florida:

mean sea level trend key west flKey West  Note the lack of any acceleration. Here are the 50-year trends for Key West, with the trend values located at the center of the 50-year interval.

variation 50 yr sea level trend key west flNow, look at the error bars (vertical “whiskers” with horizontal lines top/bottom). If the error bars of two trends overlap, the difference between them is NOT statistically significant. And in this record, every single error bar overlaps every other single error bar … meaning there is NOT any acceleration of sea level rise over the period 1915-2015.

Next, the corresponding graphs for Pensacola, Florida, only slightly shorter:

mean sea level trend pensacola flPensacola

variation 50 yr sea level trend pensacola flAgain we see the same thing. All of the error bars overlap. No acceleration.

Now, in case you mistakenly think this lack of acceleration of sea level rise is unique to Florida or New York, let me point you to and quote from an article in the Journal of Coastal Research. The authors sum up their study as follows (emphasis mine):


Our analyses do not indicate acceleration in sea level in U.S. tide gauge records during the 20th century. Instead, for each time period we consider, the records show small decelerations that are consistent with a number of earlier studies of worldwide-gauge records. The decelerations that we obtain are opposite in sign and one to two orders of magnitude less than the +0.07 to +0.28 mm/y2 accelerations that are required to reach sea levels predicted for 2100 by Vermeer and Rahmsdorf (2009), Jevrejeva, Moore, and Grinsted (2010), and Grinsted, Moore, and Jevrejeva (2010). Bindoff et al. (2007) note an increase in worldwide temperature from 1906 to 2005 of 0.74uC.

It is essential that investigations continue to address why this worldwide-temperature increase has not produced acceleration of global sea level over the past 100 years, and indeed why global sea level has possibly decelerated for at least the last 80 years.

Note that the “sea levels predicted for 2100 by Vermeer and Rahmsdorf (2009), Jevrejeva, Moore, and Grinsted (2010), and Grinsted, Moore, and Jevrejeva (2010)” are the standard alarmist predictions of sea level rise. The study says that not only is there no acceleration in the record, sea level rise has possibly slowed very slightly over the last eighty years … go figure.

So like I said, this is an opportunity for Dr. Flatow (he has a couple of honorary PhDs …) to abjure his mistaken ways. I’m posting this here, and I’m also sending a copy to him, as well as to other PBS addresses … we’ll see how it plays out. I’d be most happy if he were to post a reply here stating something like ‘If the data changes I change my mind … what do you do?’, but that may be too much to hope for.


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