For years, the world’s top scientists have known that they cannot prove there has been an acceleration of sea level rise, and yet they have told the public that they can. Now we know how they did it
By Michael Shellenberger, Public News, Oct. 24,2025
For years, the Intergovernmental Panel on Climate Change (IPCC) has claimed that human-caused climate change has accelerated sea level rise. But that claim is false. There is no scientific evidence of accelerated sea level rise since the mid-19th Century, and thus none showing human-created emissions caused an acceleration in recent decades.
This does not mean that climate change isn’t happening. It is. It simply means that it has not caused the sea level to rise at a rate any higher than one would expect without human-caused climate change.
Not only that, but the top scientists know this fact and have deliberately misrepresented it for years, deceiving the public.
In September, I reported on one of the first global studies of sea level rise that used tide-gauge data, which is the only real-world data that goes back long enough, to the mid-19th Century, that would allow one to detect whether sea level rise had accelerated, decelerated, or remained steady.
Since then, I exchanged over 50 emails with one of the world’s leading sea level rise scientists, Robert Kopp from Rutgers University, and heard back from IPCC, NASA, and NOAA, the National Oceanic and Atmospheric Administration.
What I learned shocked me. For years, the world’s top scientists have known that they cannot prove there has been an acceleration of sea level rise, and yet they have told the public that they can.
Not only that, in the process of this exchange, I gained a glimpse into how the scientists have been able to mislead journalists, policymakers, and the wider public for so long.
Sea level rise has, since the 1990s, been the main justification for apocalyptic climate claims, and past efforts to debunk sea level rise have failed to show that scientists were deliberately misleading.
The media and others have published terrifying maps of the future showing cities underwater. Accelerated sea level is one of the main justifications for predicting very high costs for adapting to climate change. And while good scientists have debunked acceleration claims in the past, they did not clearly show how IPCC scientists engaged in their manipulations.
While good scientists have debunked acceleration claims in the past, they did not clearly show how IPCC scientists engaged in their manipulations.
Not only can I prove that the real-world data do not support the claims that there has been an acceleration, I can show that the scientists deliberately misrepresented their research, and how they did it, thanks to my on-the-record email conversation with Kopp of Rutgers.
How They Did It
Scientists engaged in multiple forms of manipulation. First, they introduced modeling that, depending on the assumptions, could show deceleration, linearity, or acceleration. However, given that we have over 150 years of real-world data, they didn’t need to use such complicated modeling.
Second, they used alternative and indirect measures to tide gauge data of sea level rise, whose presentation they manipulated to show acceleration.
Third, they used data from periods of time that are far too short to detect a long-term trend. Sometimes scientists point to satellite data that show acceleration over the last 30 years, but that’s far too short a period of time to show a long-term trend. Proof of that is that the period from the 1920s to the 1950s, before there were significant human-caused greenhouse gas emissions, had comparable levels of acceleration
The period from the 1920s to the 1950s, before there were significant human-caused greenhouse gas emissions, had comparable levels of acceleration
What you’ll see in my exchange with Kopp is that he points to models, alternative data, and short-term data to imply that they support his claim of acceleration. His behavior makes clear that he understands perfectly well that he does not have the scientific evidence to claim an acceleration.
And so Kopp uses irrational tactics, including non sequiturs, or statements that do not follow logically, credentialism, or appeals to his authority as a scientist who knows more, and ad hominem attacks, namely criticisms and insults, to derail our conversation and distract attention away from the central fact that there is no real-world scientific evidence to support his claim of acceleration.
The result is, I believe, more than a damning indictment of Kopp and the other sea level scientists. It is also a fascinating look into how political activists posing as scientists can use rhetoric and bullying to maintain their deception over time. If this is the strategy Kopp has used over the years, then it helps explain why the world has been deceived for so long.
Kopp emails privilege alarmist set of model assumptions
Between September 2 and 4, Kopp and I each sent over two dozen emails to each other. In his first email, Kopp says, Voortman’s recent tide gauge study showing no acceleration “does not cite and does not appear to address the concerns raised in the 10-year-old paper Visser, H., Dangendorf, S., & Petersen, A. C. (2015)…”
But the Visser et al. study shows that different statistical approaches can yield acceleration, linearity, or even deceleration depending on model choice, sampling window, and treatment of variability.
And it’s not just Visser. The peer-reviewed scientific literature as a whole openly acknowledges that the models are assumption-dependent, even as the IPCC’s Summary for Policymakers claims “very high confidence” in acceleration.
In Kopp’s first response to me, he implies that Visser et al. and Dangendorf et al. disprove Voortman and De Vos’ study, but they don’t. As noted above, Visser shows that different statistical approaches can show acceleration, linearity, or even deceleration. Dangendorf et al. use a combination of observations and models that have the same problem.
Tide-gauge figures, not models, should be first source of data
“There are many studies that have done tide gauge level analyses,” Kopp wrote, “with different regression models, and Visser et al address the differences among them.”
I respond by asking “how the community justifies privileging one set of results over others, given Visser et al.’s own demonstration that the answer is highly method-dependent.”
I acknowledge that we have other lines of evidence (altimetry, GRACE, Argo, paleo) but that they don’t contradict the tide gauge data, which is the longest instrumental record we have and it directly, rather than indirectly, measures sea level.
As for satellite altimetry data, it indeed shows an acceleration over the last 33 years, but that is too short to substitute for a century-plus of tide gauge data.
Kopp writes, “You seem to be saying that scientists should ignore the fact that global mean sea-level is observably accelerating…”
But, again, sea level rise is not “observably accelerating” over time horizons that would show a trend. The only scientific basis for claiming it is accelerating is through modeling. The observable tide-gauge data do not show this. To call model outputs “observable” is deliberately misleading.
At this point, Kopp finds another way to talk around the problem by suggesting that he and his colleagues had not misled the public because “high confidence” refers to an assessment based on multiple sources.
In sum, our email conversation reveals how Kopp repeatedly introduces irrelevant information clearly aimed at derailing and distracting attention from three essential facts.
First, the long-term tide-gauge record does not show acceleration. Second, the models they introduce can show acceleration, deceleration, or linearity. And, third, by cherry-picking the model outputs showing acceleration, and even using models at all, rather than direct, real-world tide gauge data alone, proves that Kopp, his colleagues, and the IPCC are covert political activists who have deceived the world into believing that sea level rise is accelerating.
Abuses of Power
Five days after our exchange, Kopp and 15 of his colleagues demanded that the Journal of Marine Science and Engineering retract the Voortman study. They wrote that the Journal’s reviewers “failed to recognize the context of this manuscript and the breadth of the existing literature, resulting in at best a superficial review. Upon close examination, we believe the paper contains fatal methodological flaws that compromise the validity of its conclusions and merit retraction.”
But anyone who understands what I explained above will understand what they are doing.
They say that Voortman “stands in contrast both to other studies conducting similar tide-gauge analyses.” Note the language. They don’t say that other studies disprove Voortman; they say it “stands in contrast.” Nor do they say the studies did the same tide-gauge analysis; they say “similar tide-gauge analyses.”
That’s the same strategy Kopp and other scientists use to give people the impression of certain conclusions without directly lying. They complain that Voortman “failed to recognize the context… and the breadth of the existing literature…” But failing to recognize context does not mean the results are wrong.
They say, “Upon close examination, we believe the paper contains fatal methodological flaws…”
Tide-gauge data shows no acceleration
And perhaps it does. I do not know. What I do know is that it doesn’t matter if it does. The tide gauge data is the tide gauge data. They do not show an acceleration. And every other way the scientists claim to find acceleration is not scientifically valid, meaning they do not accurately measure what they appear to be measuring.
Here’s the bottom line. There is no scientific evidence that sea level rise has accelerated, and, rather, abundant evidence that a group of political activists posing as scientists unnecessarily introduced models, and then cherry-picked their most alarmist outputs, used indirect data, and data from too short of time periods, to deceive the public.
And this is hardly the first time that someone has cherry-picked periods of time too short to show a trend. The New York Times did this on landfalling hurricanes, as you can see below with their graph starting from 1980, even though the data goes back to 1900 and shows no increase.
Media cherry-pick post-1980 period to mislead readers
And the Environmental Protection Agency (EPA) still does this on heat waves. Google “EPA heat waves” and the first web page you’ll see reveals graphs since the 1960s. Then,the EPA made its graph from 1890 difficult to find on its website. It shows a massive spike in the 1930s before significant human emissions.
In the end, the fact that there’s no acceleration in sea level should not surprise us, given that we’ve known since 2018 that 89% of the atoll islands that scientists and the media claimed would be destroyed by sea level rise had instead grown or stayed the same size.
If I had to predict how Kopp and his allies respond to this, I suspect they will use distracting non sequiturs, authoritarian credentialism, personal demonization or ad hominem attacks, and obfuscation. “You can’t teach an old dog new tricks.”
The scientists cannot change because they have sunk their entire lives and reputations into a massive deception. It will be interesting, from a strictly psychological point of view, to watch how they behave as more people realize that they deliberately deceived the world.
The scientists cannot change because they have sunk their entire lives and reputations into a massive deception.
This scandal is also a damning indictment of mainstream media journalists. They not only failed to see through the charade, some of them may have participated in it — all while, no doubt, telling themselves and other that they were neutral and objective “science journalists” committed to reporting the truth.
The Intergovernmental Panel on Climate Change must not only immediately correct its false claim, it should invite an independent group of experts, including scientists, journalists, and policy experts, to investigate the scandal. If it fails to do so, then it will become increasingly clear to the world that it, and the scientists who create its reports, simply cannot be trusted.
This article has been edited for length. For the original article on Public News, click here.