Here’s the graph from NOAA of sea level at Pensacola, FL (tide gauge data)
Some might actually look at that and think “steady rise,” but the readers of this blog would probably think otherwise. Here’s my graph of the same data:
For years, the Dave Burtons and Judith Currys of this world have shown a graph (from NOAA) of sea level measured by a single tide gauge at one location, followed by proclamations of “no acceleration” and/or “sea level rise has been steady.” They choose one for which the visual impression given by the graph supports that idea, whether the numbers do or not, especially since NOAA conveniently adds a best-fit straight-line to their graphs of tide gauge sea level, and putting a straight line on the graph plants the idea of straight-line trend (i.e. constant rate of sea level rise).
If your science gives you a result you don’t like, pass a law saying the result is illegal. Problem solved.
— Stephen Colbert
Back in 2010, North Carolina’s Coastal Resource Commission released their North Carolina Sea Level Rise Assessment Report. It suggested that communities should be prepared for 1 meter (that’s over 3 feet) of sea level rise this century. They didn’t say there would be 1 meter of sea level rise … but it was a distinct possibility, so communities should be prepared.
We have measured sea level at the Battery in New York for over 150 years, from 1856 to the present, albeit with a 14-year gap from 1879 to 1893. The monthly-average sea level data are available online from NOAA (as are the data from hundreds of tide gauge stations around the world). They even provide a convenient graph:
I’m flattered.
After posting about three different reconstructions of global sea level since 1900, I happened upon another one, this time from Frederikse et al. It’s the latest, and the team of collaborators includes top researchers on this subject, some of whom were involved in previous reconstructions. What flatters me is that it agrees so well with my own reconstruction, better than it agrees other previous efforts. If the new one is the best there is (and it seems to be), then mine is impressively close.
Here’s how mine (in red) compares to that from Frederikse et al. in black:
I’m not asking how fast it was rising. I looked at that in the last post, using three different reconstructions of sea level since 1900 based on tide gauge data. And my goal wasn’t really to estimate the rate of sea level rise, as much as it was to show that the rate has not been steady, it has changed over time; in fact it has gotten faster (acceleration).
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It’s easy to see that sea level rise has not been steady. It has accelerated.
In fact it has accelerated a lot, especially recently. For most of the 20th century, it rose sometimes faster, sometimes slower, but for the last few decades its rise has picked up speed. The clearest demonstration is the change in global mean sea level. There are several different estimates of that based on historical data from tide gauges around the world, which differ on how much and how fast sea level has risen, but they all show — without a doubt — that the rise has not been steady.
Open Mind 