“Dr. Walt Meier at NSIDC has convinced me this week that their ice extent numbers are solid. So why the large discrepancy between their graphs and the UIUC maps? I went back and compared UIUC maps vs. NASA satellite photos from the same dates last summer. It turns out that the older UIUC maps had underrepresented the amount of low concentration ice in several regions of the Arctic. This summer, their maps do not have that same error. As a result, UIUC maps show a much greater increase in the amount of ice this year than does NSIDC. And thus the explanation of the discrepancy. it is clear that the NSIDC graph is correct, and that 2008 Arctic ice is barely 10% above last year – just as NSIDC had stated.”

The responsible thing to do is retract this post so that nobody gets the wrong idea.