How Rahmstorf & Vermeer Grossly Exaggerated Sea Level Rise

Rahmstorf and Vermeer 2009: The art of mathematical distortion. (Photo source: Wikipedia)

Tom Moriarty at Climate Sanity has done a thorough analysis of Stefan Rahmstorf ‘s and Martin Vermeer’s PNAS 2009 paper Global Sea Level Linked To Temperature, hereinafter RV2009, which claimed sea levels would rise 1.8 m by 2100 due to rising temperature.

Turns out they used awfully “brutal mathematical contortions” and bad assunptions to reach this figure.

Moriarty finds the paper is riddled with gross errors and false assumptions, read overview here.

New studies have since come out that would allow Rahmstorf & Vermeer to make corrections, but they are perfectly content in letting the press run crazy with their wildly exaggerated 1.8 meter figure.

Keep in mind that practically all sea level experts have called the 1.8 meter fígure hugely exaggerated, some even calling it preposterous. Even the alarmist IPCC 2007 3rd Assessment Report projects a sea level rise of 18 – 57 cm by 2100.

Most skeptic scientists project it will be in the neighbourhood of 20 cm – similar to last century. So how did Rahmstorf and Vermeer arrive at such an inflated figure? Tom Moriarty explains.

Fudging groundwater depletion and reservoir water

First, Rahmstorf and Vermeer completely neglected the sea level rise correction that is due to groundwater depletion, which is man pumping water from the ground and adding it to the oceans, read here. Moriarty writes:

About 25% of the yearly sea level rise comes from pumping water from the ground and adding it to the oceans, not from melting ice. … “Mistaking this groundwater as ice-melt-water in calculations designed to ferret out the effects of global temperature on sea level greatly prejudices the calculations toward higher sea levels in the future.”

RV2009 improperly, but gladly, applied corrections by Chao to account for man-made reservoirs of water that would otherwise be added to ocean volume, thus boosting computed future sea level rises. But at the same time, they conveniently neglected groundwater depletion because that correction would have led to subtracting from sea level rise caused by rising temperature.

When asked why this was done, Rahmstorf and Vermeer said there were no adequate datasets on groundwater depletion available. Now a recent Geophysical Research Letters paper (Wada, Y., L. Pet al (2010), Global depletion of groundwater resources, confirms that “Vermeer and Rahmstorf were low-balling the effect of groundwater depletion”.

Moriarty, citing Geophysical Research Letters:

It seems preposterous not to include a correction for groundwater depletion when its effect is ‘the same order of magnitude as the contribution from glaciers and ice caps’.”

That means that RV2009 overstated the effect of temperature on sea level rise by a factor of two.

RV2009 also used outdated sea level rise data

Next, Rahmstorf and Vermeer used old, outdated sea level data from Church and White to model sea level rise for the future. At about the time RV2009 was published, Church and White came out with revised data showing that sea levels were rising more slowly instead, read here.

The new 2009 version of Church’s and White’s sea level data extended out to the year 2007.  More importantly, it also had corrections that drastically changed the sea level versus time for the previous 100 years.

What do these new sea level, groundwater deletion and reservoir numbers mean?

When these new numbers are inserted into Vermeer’s and Rahmstorf’s model equation, and 21st century IPCC temperature scenarios are applied, the resulting sea level predictions are half of what Vermeer and Rahmstorf claim.

Testing the RV2009 formula.

Moriarty also reverse tested the RV2009 formula by applying it to the best sea level data available, from the Topex and Jason-1 satellites, read here. Note how the RV2009 formula-calculated sea level shows an accelerating rise rate, in contradiction to the actual satellite data showing a decreasing rate. VR2009 is off in the wrong direction.

Rahmstorf Sea Level trend compared to actual satellite. Source; Climate Sanity

And when Moriarty back-calculated the temperature increase by plugging in the sea level rise data into the formula, the result is a preposterous temperature increase, proving their formlua is junk.

Moriarty concludes:

Let’s face it, Vermeer’s and Rahmstorf’s sea-level rise predictions come from the forced confession of innocent data.  Every effort is made, no stone unturned, in a quest to wring out as much sea level rise as the most gullible audience will believe.

RV2009 refuse to correct their projections.

Rahmstorf and Vermeer have yet to correct their calculations, and are content to see the media continue using their wildly exaggerated projection. And let’s not forget that the NAS allowed such a faulty piece of work to be published, likely because it suits the prevailing dogma there.

Moriarty attempted to bring this to the authors’ attention, but without success. He even left a post at RealClimate, where Rahmstorf is a contributor. Not surprisingly, real science has a way of being deleted at RealClimate, read here.


Tom Moriarty is a Senior Scientist at the US Department of Energy’s National Renewable Energy Laboratory. He has a masters degree in Physics and previous experience in two other national laboratories, Argonne National Laboratory and Fermi National Accelerator Laboratory.

Source: How Rahmstorf & Vermeer Grossly Exaggerated Sea Level Rise

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