[UPDATE: Several commenters, including myself, have remarked on a mathematical error in the author’s work. I note this here in the expectation that the author will return to clarify and perhaps amend his claims. Having made such public mistakes myself, it’s embarrassing if true, but that’s the function of public peer review as practiced on WUWT. Thanks to all who pointed out the error. -w.]
A graph on NOAA’s 2012 “Greenland Ice Sheet” report uses a 2006 modelled projected ice melt for 2012 that is over ten times that in the latest published paper and equivalent to 250% of the long-term sea-level rise of 3.2mm per annum.
Guest essay by Kevin Marshall (posts as ManicBeancounter)
NOAA published on 01/14/13 a “Greenland Ice Sheet” paper as part of its “Arctic Report Card: Update for 2012″. Fig 5.19 shows ice-mass balance loss in gigatonnes and sea level rise equivalent.
In 2012, the ice mass loss is modelled have raised sea levels by 8mm. This is 250% of the average sea level rise trend of the last twenty years of 3.2mm. The graph has a note “After Velicogna and Wahl 2006″. The graph used 49 months of GRACE modelled data to project 80 months forward.
I compare with more recent papers. Last Fall they could have used Rignot et. al 2011. Using 99 months of modelled data, to project 30 months forward, with Greenland ice melt contributing 1.1mm to sea level rise. Now they could use Shepard et. al 2012. Using 96 months of modelled GRACE data (plus other sources going back to 1992), to project 24 months forward, with Greenland ice melt contributing 0.7mm to sea level rise.
A common author of the NOAA paper, the 2006 paper and Shepard et. al 2012 is John Wahr, who works at University of Colorado Boulder. Another department produces the sea level rise figures.