Sea Level Mis-information from DOE | Open Mind
Posted on August 3, 2025 |
Here in the USA, the Department of Energy (DOE) has issued a report titled “ A Critical Review of the Impacts of Greenhouse Gas Emissions on the U.S. Climate.” It is a product of the “Climate Working Group,” five Ph.D.’s with one thing in common: a history of climate denial. They were commissioned by DOE director Chris Wright, previously chairman and CEO of the fossil fuel company Liberty Energy.
It’s a long report covering a lot of topics. They devote chapter 7 to sea level rise, and here is their “chapter summary” (I have highlighted, in bold, its final sentence):
Chapter Summary
Since 1900, global average sea level has risen by about 8 inches. Sea level change along U.S. coasts is highly variable, associated with local variations in processes that contribute to sinking and also with ocean circulation patterns. The largest sea level increases along U.S. coasts are Galveston, New Orleans, and the Chesapeake Bay regions – each of these locations is associated with substantial local land sinking (subsidence) unrelated to climate change.
Extreme projections of global sea level rise are associated with an implausible extreme emissions scenario and inclusion of poorly understood processes associated with hypothetical ice sheet instabilities. In evaluating AR6 projections to 2050 (with reference to the baseline period 1995-2014), almost half of the interval has elapsed by 2025, with sea level rising at a lower rate than predicted.U.S. tide gauge measurements reveal no obvious acceleration beyond the historical average rate of sea level rise.
They mention (by name) five U.S. tide gauge stations, and list the rate (at each location) of RSLR, or relative sea level rise, which is measured by the tide gauge itself. It’s how fast the sea is rising relative to the land, as seen at that location, and varies (dramatically) from place to place. They also list the rate of VLM (vertical land movement), which measures how fast the land itself is rising or falling, which also varies from place to place. Their sum is ASRL (absolute sea level rise), which is how fast the sea itself is rising at that location (and yes, that too varies from place to place). Their numbers are in table 7.1:
They also show graphs ( taken from NOAA) for four of the five listed stations; the one they don’t show is St. Petersburg, FL. I retrieved the data for St. Petersburg (from the NOAA website) and computed both yearly average sea level and the best-fit straight line (shown in blue):
That best-fit line rises at a rate of 3.14 mm/yr (or 0.12 inches/year). That’s the rate they quote in their table; clearly it’s the average rate over the period of record (from 1947 through 2024).
But when we look at the residuals from that straight-line fit, there seems to be more going on than just random noise:
On the left-hand side (early times) and right-hand side (late times) the residuals tend to be positive, but in the middle they tend to be negative. That’s a sure-fire sign of acceleration in the residuals, which means acceleration in the data itself. One might even say, that there is obvious acceleration of sea level rise at St. Petersburg.
But, “obvious” is such a subjective term, and (as I often point out) it can happen that a graph will show what seems obvious when the numbers — the statistics — don’t agree. I believe in running the numbers. If we want to know whether or not there’s acceleration, let’s test for it statistically.
The most obvious test is to fit a quadratic function of time, rather than a straight line. We can also fit a quadratic to the residuals (which gives the exact same statistical significance). The graph of that fit makes it look even more obvious:
But I reiterate, don’t go by the “obvious” graph, go by the numbers. The numbers say, with p-value 99.9%), that yes there’s acceleration.
Fitting a quadratic isn’t the only test. One of my favorites is to fit a PLF (continuous piecewise-linear function) with a slope change at a time chosen by changepoint analysis. This is a challenging analysis statistically because of the freedom to choose the change point, but as often happens, Monte Carlo simulation is our friend. It too can be applied to the data or to the residuals from the linear fit (with equivalent statistical significance), and it too shows that yes, there is acceleration, with more than 99.9% confidence. I would add that when graphed, it too makes the situation look “obvious”:
Here’s how the model fits to the data (rather than residuals); the rate before 2006 was about 2.36 ± 0.41 mm/yr (0.09 ± 0.02 inches/year), but is now much higher at 7.86 ± 1.69 mm/yr (0.31 ± 0.07 inches/year) (95% CI):
Sea level rise at St. Petersburg, FL reveals obvious acceleration beyond the historical average rate of sea level rise. This it true whether I define “obvious” as an impressive visual graph, or as overwhelming significance of a statistical test. I wonder whether the obvious acceleration at St. Petersburg is the reason they chose not to display its graph, despite including it in their table?
Do other stations show acceleration — obvious or otherwise? Perhaps the tide gauge record most often displayed (esp. by climate deniers) is from New York City (at the Battery):
Residuals from the best-fit straight line (the blue line in the graph) look like this:
Again, the residuals give the distinct impression of high on the sides and low in the middle, a sign of acceleration. But it’s not as obvious visually until I add a best-fit quadratic function:
Let’s not get carried away by visual impressions, let’s check the numbers. In this case, > 99.9% confidence. Yes acceleration. There’s also the PLF-changepoint test, and that too gives > 99.9% confidence:
When we fit the PLF-changepoint model to the data, it suggest the rate of sea level rise increased from about 2.76 ± 0.16 mm/yr (0.11 ± 0.01 inches/year) prior to 2002, to right around 6.38 ± 1.53 mm/yr (0.25 ± 0.06 inches/year) since.
Looking at these two (of the five stations on their list), we already found obvious acceleration beyond the historical average rate of sea level rise. That’s true for a lot of U.S. tide gauge stations, running the numbers with the most up-to-date data shows acceleration unambiguously, it’s not a close call. The same is true for regional composites of sea level along U.S. coasts, and if we look closely, we find even more complex behavior of acceleration and deceleration, with acceleration dominating the last fifty years almost everywhere.
It is just not true, as any competent analysis of the available data will show, that “U.S. tide gauge measurements reveal no obvious acceleration beyond the historical average rate of sea level rise.” How, then, did they reach that false conclusion?
I suspect it’s a combination of two factors. First, that bit of mis-information has been repeated by climate deniers for years, for decades in fact. Second, they didn’t do any analysis at all. There is no mention, anywhere in the report, of any analysis or statistical test to look for the presence or absence of acceleration. They don’t mention any of the (very few) peer-reviewed papers which support their idea, probably because those are old (and rather bad, in my opinion) and if you open that can of worms, there is a helluva lot more recent research showing acceleration, beyond doubt, and emphasizing how much sea level has accelerated recently.
Of the five stations they list in their table, the one which shows the most obvious acceleration (St. Petersburg) is the one they don’t show the graph of! Of course they didn’t find acceleration in U.S. tide gauge records, because they never looked for it. They only looked for what they wanted to see, and that’s all they found. If you do analyze sea level data (and I have), in light of the most recent data (from satellites and from tide gauges) acceleration is obvious, both for the U.S.A. and the globe as a whole.
I took data from all the tide gauge stations in the USA which, according to PSMSL, have at least 40 years of data since 1970. Then I tested the data since 1970 for statistically significant acceleration. Here’s a plot showing stations without significant acceleration as black “x” marks, stations with significant acceleration as red dots. I’d say that acceleration along the east coast of the USA is obvious:
Acceleration of sea level rise beyond the historical average rate is a fact. It’s one of the most worrisome facts about man-made climate change, so of course it’s a truth that fossil-fuel pushers don’t want you to you believe. The U.S. government and our Department of Energy now fit into that category: fossil-fuel pushers. |
