NSIDC Caught Cooking The Books
By Paul Homewood
Tony Heller has a couple of posts up at Real Science, which seem to expose some extremely dodgy behaviour on the part of NSIDC.
Regardless of Arctic sea ice extent trends in recent years, they have been consistently showing a recovery in multi-year ice since 2008. For instance, this was their chart for March 2015:
As can be seen, the proportion of 3-year and above ice has steadily increased since 2009. Also, both 4 and 5-year ice have risen since 2011 and 2012 respectively. This is natural, since an increase in 3-year ice in 2010 will turn into 4-year ice the following year, and so on.
Yet now, in their latest monthly report, NSIDC show a totally different picture. To confuse matters, the chart is tipped upside down, but the amount of 1 and 2-year ice is broadly the same now as in 2009, again for week 11.
With a slightly lower total extent, this would imply that the percentage of this younger ice has actually increased.
Tony Heller has commendably tracked down how NSIDC has revised its own historical data, with these before and after maps of sea ice age:
These are for week 41 last year, ie October. The old NSIDC style graph, which they have used for years, shows a mass of 5-year ice across the Canadian archipelago and the north of Greenland.
Then, in their wisdom, NSIDC then decided to introduce a new map:
Look closely, and you will notice that the area of 5-year ice has noticeably shrunk, particularly that tongue to the north of Greenland. I would recommend reading both Tony’s posts, here and here, as they give the full story.
Disgracefully, NSIDC have now deleted the archives for all of the older style maps. They have also given no explanation, as far as I am aware, of why they have revised their historical data so significantly.
It is worth pointing out though that the old style sea ice age chart, which I have shown above, was always published in the March or April review each year. But last year, it never appeared – they eventually sent me a copy, following my request, along with some sad little excuse. My suspicion at the time, which has now been borne out, was that a chart showing increasing multi-year ice was not compatible with the official line of rapidly disappearing ice.
It therefore seems that, in good old climate science tradition, they have simply adjusted the inconvenient data.
Just like NOAA and GISS, it is evident that we can no longer trust anything coming out of NSIDC.