Did the Arctic Ice Sheet grow by 60% from 2012 to 2013?

Question

I came across this picture on Facebook.

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??

Answer 1

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.

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.

Answer 2

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.

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):

Answer 3

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