Correction on NSIDC Graph
I recently wrote two pieces about the Arctic Ice recovery, and about the faulty graph used by the National Snow and Ice Data Center. The original story was based on a piece from Stephan Goddard, and I found out about it via Tom Nelson (a very reliable source). It turns out that the author has revised his analysis based on conversations with the NSIDC; the differences in the photographs he used to determine ice loss was based on pixel counts, and the pixels used different parameters, so the apparent contradiction has been resolved-at least as far as the original author was concerned.
Here is a statement by Goddard:
To expound further - after a lot of examination of UIUC maps, I discovered that while their 2008 maps appear golden, their 2007 maps do not agree well with either NSIDC maps or NASA satellite imagery. NSIDC does not archive their maps, but I found one map from August 19, 2007. I overlaid the NSIDC map on top of the UIUC map from the same date. As you can see below, the NSIDC ice map (white) shows considerably greater extent than the UIUC maps (colors.) The UIUC ice sits back much further from the Canadian coast than does the NSIDC ice. The land lines up perfectly between the maps, so it appears possible that the UIUC ice is mapped using a different projection than their land projection.
Because the 2007 UIUC maps show less area, the increase in 2008 appears greater. This is the crux of the problem. I am convinced that the NSIDC data is correct and that my analysis is flawed. The technique is theoretically correct, but the output is never better than the raw data. Prior to writing the article, I had done quite a bit of comparison of UIUC vs. NSIDC vs. NASA for this year. The hole in my methodology was not performing the same analysis for last year. (The fact that NSIDC doesn’t archive their maps of course contributed to the difficulty of that exercise.)
My apologies to Dr. Meiers and Dr. Serreze, and NSIDC. Their analysis, graphs and conclusions were all absolutely correct. Arctic ice is indeed melting nearly as fast as last year, and this is indeed troubling.
- Steven Goddard
Here is an explanation of the changes made by the William Chapman of the University of Illinois Champagne/Urbana on the changes he made to the sea-ice graph, changes that caused the confusion.
Here is a piece from the Rockymountain news in which Walt Meier of the NSIDC explains that, yes, this year was colder than last, and that it is most unlikely that we will have an ice-free Arctic this year. As he points out:
“We only have about two or three weeks more of ice melt, and it’s not going to make it to the North Pole,“ Meier said.
The Arctic Ocean has two types of ice. One type is the seasonal ice that starts forming in late September, typically reaches 10 to 15 feet thick, and may or may not survive the summer’s heat.
The second type is the perennial ice that lasts year after year — at least it has until the last couple decades when so much of it has melted.
NSIDC scientists got interested in a possibly ice-free North Pole this year when they noticed that that perennial ice had retreated south of the North Pole. That left only the seasonal ice.
But the season was cooler than expected, so the seasonal ice is holding. “We’re not going to set a record every year,“ Meier said.
End Excerpt
Although Meier blames Global Warming, you will note this interesting comment from Arctic Sea Ice News, the NSIDC`s periodical:
Sea ice extent is declining at a fairly brisk and steady pace. Surface melt has mostly ended, but the decline will continue for two to three more weeks because of melt from the bottom and sides of the ice. Amundsen’s Northwest Passage is now navigable; the wider, deeper Northwest Passage through Parry Channel may also open in a matter of days. The Northern Sea Route along the Eurasian coast is clear.
Hat tip; Tom Nelson.
End Excerpt
Catch that? The ice is melting from beneath, not above. What does that tell us? That warmer water is coming into the Arctic, melting the ice. It is not melting because of high Arctic temperatures, but because of ocean currents.
Remember, the Antarctic is GAINING ice
With all that said, the main point of my pieces may have been wrong, but the ancillary points-that the press is in the tank on GW and only reports those making apocalyptic statements is spot-on, and there is still no reason to believe we are facing environmental catastrophe.
The Alarmists have been trolling websites; they think they`ve got the goods based on this one argument. You gotta love people who call for trials of those who disagree with them!
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