I came across this picture on Facebook.

Claiming ice sheet has grown by 60%

The image claims to have been taken from a NASA satellite. I am skeptical this is correct, and if it is, does it show the ice sheet has increased in size during this period??

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    Is there a notable claim that it is as thick as in 2012? The claim you've cited just refers to surface area. I agree that any good answer would address both, but it's important to be clear about just what claim is being addressed. – EnergyNumbers Sep 11 '13 at 18:33
  • @EnergyNumbers No, there is no claim saying that. My guess is that this is cherry picking and information manipulation. – Zonata Sep 11 '13 at 18:39
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    Or that the 2013 summer was much milder than the 2012 summer leading to a reduction in summer icemelt. Compare it to peaks and averages rather than 2 data points. Any 2 datapoints are meaningless – Chad Sep 11 '13 at 20:05
  • After this article was released the various debunkers set to work putting together the actual data to show how this was wrong. Potholer did a great video on this. I recommend installing rbutr in your web browser and linking articles as well as seeing rebuttals that others have posted. – Tim Scanlon Sep 18 '13 at 3:42

Technically, yes. Is this an actual measure of anything useful? No.

This is an example of an extreme version of data cherry-picking. The explanation is very simple.

The level of sea ice fluctuates. 2012 was an extremely bad year for sea ica - really really bad. It was down, at its lowest to barely half what it normally is. Given that, it was absolutely certain that 2013 would be a better year for sea ice than 2012, and a number of people have posted the fact in an attempt to convince us that sea ice isn't decreasing - which, if you look at more than a one year comparison, it clearly is. The 2013 figures are still way down compared with the average of the last 30 years. The posting does serve to refute exaggerated claims made last year from equally misleading data that sea ice would be gone in a few years.

Graph of Arctic sea ice

Given today's date, I'll make this comparison - it's like posting the number of murders in New York for September 2002, and claiming that because it's far fewer than the previous year, crime must be on a downward trend.

tl;dr The posted factoid is a massively misleading case of selected data, and certainly doesn't indicate any reversal of global warming.

Reference for all this is this article from Slate.

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    I agree it is misleading. Just as it was misleading to post the picture in 2012 and say that the cap is nearly gone and probably not coming back... – Chad Sep 11 '13 at 20:09
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    I don't feel these statements are in any way equivalent as suggested here. 2012 was the lowest ice level on record and part of an continuing downward trend with some fluctuations. The statement in the OP gives an totally wrong impression while what @Chad said is not much more than simplification and a slight exageration given that their is a clear downard trend. – Erik Sep 12 '13 at 9:43
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    @Chad - Do you have a source for someone claiming that the ice cap was not going to return? I don't recall seeing that anywhere. – Mark Sep 15 '13 at 22:14
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    @mark - I never said it was. But the media was all over this. It was disingenous then and this claim that it has completely recovered is as well. And so is the idea that by buying carbon credits that global warming can be reversed. – Chad Sep 18 '13 at 13:47
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    I think this has long departed the topic. Chat? – DJClayworth Sep 18 '13 at 13:48

I think the figure (from the National Snow and Ice Data Center) shown below puts the claim into a proper context. The sea ice extent for August 2012 was 4.71 million square km and 6.09 for August 2013, and the area from 2.56 to 3.83 million square km (which presumably gives rise to the 60% figure). So the claim is correct, but I suspect used to imply a misleading conclusion. The trend in Arctic sea ice extent is clearly downwards (even more dramatic if you look at sea ice volume), but there is quite considerable variability from year to year. For example, there was also a large increase from 1994 to 1995, but this doesn't imply there was a meaningful recovery in sea ice extent and that the long term decrease had slowed, stopped or reversed. I rather doubt the "recovery" this year is meaningful either, and says more about Arctic weather rather than climate trends.

Note that last year was a very unusual year, with the observed September minimum being very much at the lower end of what statistical methods predicted were plausible. Looking at the data, record minima are generally followed by an increase (a phenomenon known in statistics as "regression to the mean"), so one would have expected this years extent to be substantially higher than last years, however (pleasingly) the increase has been more than would be expected (or indeed hoped for).

However, having said which, the long term trend is downward, and the Arctic summer sea ice is is disappearing, and once gone is unlikely to come back very quickly due to the albedo feedback mechanism.

enter image description here

Edit: I suspect the pictures are computer generated images using satellite derived data to estimate the edge of the ice extent (if they were direct images, of course, there would be clouds and cracked/patchy ice etc.). The data from the NSIDC suggest that (with the right choice of definition) the claim is reasonable. Here are the comparable extent maps from the NSIDC (looks reasonable to me):

enter image description hereenter image description here


This article answers the question: https://www.facebook.com/notes/zero-co2-join-us/daily-mail-manipulating-nasa-facts-and-now-its-global-cooling/296729500466293

The secret is comparing 2013 with the right year, by that I mean that 2012 was the maximum ever recorded lowest ice cap.... so I's only normal to be bigger then the all time low

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    This answer could be improved in three ways: 1) quote from your sources - this protects us from link-rot and makes it clearer why you quoted from them. 2) go back to the original sources. You cite a Facebook rant; why should we trust it. 3) The explanation that it is normal to be bigger than a previous value is "begging the question". You need to explain why is it considered normal, even in the face of a warming trend. – Oddthinking Nov 21 '13 at 1:16

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