The Spin Cycle: Accelerating Sea Level Rise

The Spin Cycle is a reoccurring feature based upon just how much the latest weather or climate story, policy pronouncement, or simply poo-bah blather spins the truth. Statements are given a rating between 1-5 spin cycles, with less cycles meaning less spin. For a more in-depth description, visit the inaugural edition.

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A popular media story of the week was that sea level rise was accelerating and that this was worse than we thought. The stories were based on a new paper published in the journal Nature Climate Change by an author team led by the University of Tasmania’s Christopher Watson.

Watson and colleagues re-examined the satellite-based observations of sea level rise (available since the early 1990s) using a new methodology that supposedly better accounts for changes in the orbital altitude of the satellites—obviously a key factor when assessing sea levels by determining the height difference between the ocean’s surface and the satellites, the basic idea behind altimetry-based sea level measurements.

So far so good.

Their research produced two major findings, 1) their new adjusted measurements produced a lower rate of sea level rise than the old measurements (for the period 1993 to mid-2014), but 2) the rate of sea level rise was accelerating.

It was the latter that got all of the press.

But, it turns out, that in neither case, were the findings statistically significant at even the most basic levels used in scientific studies. Generally speaking, scientists report a findings as being “significant” if there is a less than 1-in-20 chance that the same result could have been produced by random (i.e., unexplained) processes. In some fields, the bar is set even higher (like 1 in 3.5 million). We can’t think of any scientific field that accepts a lower than a 1-in-20 threshold (although occasional individual papers do try to get away with applying a slightly lower standard).

But in the sea level rise paper that is getting all the attention, the author’s team push a result—an acceleration in sea level rise—that has about a 1-in-4 chance of being zero or below—i.e., that no acceleration in actuality is taking place. That’s like betting the farm that you won’t get two heads in a row when flipping a coin. No one outside of someone who is extremely desperate would make such a bet.

Given such a result—a finding that grossly failed the standard test of statistical significance—the  authors of the paper should have concluded that over the past 22+ years, there has been no reliably detectable change in the rate of sea level rise in the satellite-observed dataset.

Instead, the lead authors wrote in their paper’s abstract that:

“[I]n contrast to the previously reported slowing in the rate during the past two decades, our corrected [global mean sea level] data set indicates an acceleration in sea-level rise…which is of opposite sign to previous estimates.”

Further down in the details of the paper (where no reporter dares to go), the authors do admit that the acceleration was in fact statistically insignificant. But that’s not the impression left to the press.

And the press, always eager for a paper predicting doom and gloom from human-caused climate change was more than happy to run with headlines like:

“Sea Level Rise Accelerating Faster Than Thought” (from Science magazine)

“Sea levels are rising at faster clip as polar melt accelerates, new study shows” (from the Washington Post)

“Sea level rise accelerated over the past two decades, research finds” (from The Guardian)

“Study: Sea level rise accelerating worldwide” (from USA Today)

For the misleading claims, and the cascade of misinformation that flowed from them, we determine that the Spin Cycle setting of this story is Permanent Press.