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A look back at “A Semi-Empirical Approach to Sea-Level Rise”

April 20, 2011

It is astonishing, but true: There are still people out there who take Stefan Rahmstorf’s 2007 Science paper “A Semi-Empirical Approach to Projecting Future Sea-Level Rise” seriously.   Since that is the case, I feel obliged to hammer one more nail into its coffin.

I have already written extensively about what happens to the 2009 Vermeer and Rahmstrof model (Global Sea Level Linked to Global Temperature, PNAS, 2009) when the outdated sea level data they used  is replaced by a newer version from the very same people who provided them with the data.  It was not good for Rahmstrof’s theme of catastrophic sea level rise. 

The same thing is true about Rahmstorf’s 2007 Science paper, which is still being referenced in journal articles and policy papers. 

Rahmstorf used sea level data from Church and White (Church, J. A., and N. J. White (2006), A 20th century acceleration in global sea-level rise, Geophys. Res. Lett., 33)  for his 2007 Science paper.  Since that time Church and White have updated their sea level data twice.  The effect of those updates on Rahmstorf sea level projections is quite stark.

I am going to keep this very simple. The following three animations show copies of Rahmstorf’s figures 2, 3, and 4, followed by my reproductions using the 2006 version of Church and White sea level data (the same version Rahmstorf used), the 2009 update of the Church and White sea level data, and the soon to be released 2011 update of the Church and White sea level data. Click on any of the animations to see a larger version. Enjoy.

Rahmstorfs figure 2, and my reproductions. The 2006 reproduction uses the same Church and White sea level data that Rahmstorf used and yields the same model constants, "a" and "b," that Rahmstorf found, thus confirming my ability to reproduce his model. The "2009" and "2011" reproductions used the updated Church and White data from those two years. Note that the reproductions using updated data result in model constants, "a" and "b," that are very different from Rahmstorfs.

Rahmstorfs figure 3, and my reproductions. The 2006 reproduction uses the same Church and White sea level data that Rahmstorf used. The "2009" and "2011" reproductions used the updated Church and White data from those two years.

 

Rahmstorfs figure 4 and my reproductions. Rahmstorfs original caption says "The gray uncertainty range spans the range of temperature rise of 1.4° to 5.8° C" based on IPCC temperature rise scenarios from 1990 to 2100. The two gray lines in my reproductions represent the same values. The 2006 reproduction gives the same result as Rahmstorf. The reproductions based on the updated Church and White data give sea level rises that are considerably smaller

2 comments

  1. Nice work, Tom!


  2. Please note that the title of the Church/White paper has actually changed in the 2011 version to merely: “Sea-Level Rise from the Late 19th to the Early 21st Century”. The word acceleration is gone🙂.



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