Guest Post by Willis Eschenbach
I don’t know what to make of this one. I was wandering the web when I came across a Reuters article about a scientific study called “Global Floating Ice In “Constant Retreat”: Study“.
The Reuters article opens with this arresting text (emphasis mine):
LONDON
Wed Apr 28, 2010 1:38pm EDT
(Reuters) – The world’s floating ice is in “constant retreat,” showing an instability which will increase global sea levels, according to a report published in Geophysical Research Letters on Wednesday.
Floating ice had disappeared at a steady rate over the past 10 years, according to the first measurement of its kind.
“Hello,” sez I, “how can the sea ice be in constant retreat?” I knew from my previous research that the global ice was not in any kind of retreat at all.
I was also suspicious because of the next part of the quote:
“It’s a large number,” said Professor Andrew Shepherd of the University of Leeds, lead author of the paper, estimating the net loss of floating sea ice and ice shelves in the last decade at 7,420 cubic kilometers.
I went out to find a graphic to explain how that kind of huge ice loss might have happened, and the best explanation I could find was this one:
Figure 1. Oooops. How the floating ice shelves cracked off and lost 7,420 cubic kilometres.
Next, I went off to find the actual paper, and discovered a curious thing.
So what did I discover … and why is their quote suspicious?
Let me start with why their quote is suspicious. It is their claim that the earth has lost 7,420 cubic kilometres of ice. As I have mentioned elsewhere, when I see numbers I automatically do an “order of magnitude” calculation in my head to see if they are reasonable or not.
I knew from my previous research that there is about twenty million square kilometres (km^2) of floating ice on the planet. I also knew that much of it out towards the edges is only a metre or two thick.
So if the ice averaged say 1.5 metres thick out at the edges where the loss happens, a seven thousand cubic kilometer loss would mean a total loss of ice area of about five million km^2, or a quarter of the area of the world’s floating ice. I think someone would have noticed that before now …
Of course, that made me wonder if the problem was in the study, or in the Reuters quote. However, that same number (7,420 cubic kilometres lost) appeared in no less than 81 other online publications. So I went haring off to find the article.
One of publications reporting the story, NewScientist, 5 May, 2010, gave the “doi:” for the article. The DOI is the “Digital Object Identifier”, and it should link directly to the article, which was supposed to have been published by Geophysical Research Letters (GRL) on Wednesday, April 28th … but the curious thing I discovered was that the DOI didn’t work.
Someone had commented on that, saying “The DOI doesn’t work.” This was replied to by someone called Marshall, from newscientist.com, who said:
Hi Eric, it’s because the article hasn’t been published on GRL’s website yet. The DOI is taken directly from our press copy of the paper, so once the article is published it should work.
OK, fair enough … although the original Reuters article was allegedly published on April 28, and today is May 28, and the DOI still isn’t working. So I went to the GRL web site to see what I could find.
I first did a search for any articles by “Shepherd” in “GRL” for “2010”, and I got this:
Figure 2. Ooooops …
Thinking it might have been misfiled, I searched through all of the May articles for anything by Shepherd. Nil. I looked through the May articles for anything regarding “ice”. Nada. I repeated both searches for April. Once again, zip. Niente. Nothing.
I thought “Well, maybe it appeared in another journal”. So I took a look on Google, but I found nothing. Google did find 32,500 instances of “ice in constant retreat”, of which 7,550 also contained “GRL”.
Google also revealed that the report of the study has been picked up by ABC News, NewsDaily, Yahoo News, New Scientist, Arab News, and ScienceDaily. It was featured on Joe Romm’s global warming blog “ClimateProgress”. It has been referred to in blogs and news reports from India, Australia, Russia, and China. It shows up on TweetMeme, Huffington Post, and Facebook. Even Scientific American has an article on it.
So at this point, it has gone round and round the world. It has been illustrated with all kinds of pictures of melting ice, and of global ice extent, and (inevitably) of polar bears. It has been discussed and debated and dissected around the web.
And with all of that publicity, with all those news reports, with all that discussion and debate … as near as I can determine, despite Reuters saying it was published a month ago, the study has never been published anywhere.
Not only that, but nobody seems to have noticed that the study has never been published.
Well, that’s not entirely true. Scientific American must have noticed, because they quietly removed the page where they had published the report … but it is still in Google’s cache.
One last thing. In all of that, in the frenzy to get out tomorrow’s news today, in the rush to report the latest scientific rumour, people seem to have forgotten to ask … how is the global sea ice actually doing?
Glad you asked. Here’s today’s information, from Cryosphere Today:
Figure 3. Daily global sea ice anomaly (red line) compared to 1979-2008 average. Link contains full sized image.
As you can see, as of today, the global sea ice is exactly on the line representing the 1979-2008 average. So over the last ten years, instead of a loss of 7,420 cubic kilometres, the loss has been … somewhere around zero. Go figure.
You know, when I was a kid I liked stories with morals, you know, like “Don’t count your chickens before they’re hatched”, that kind of thing.
But what is the moral of this story?
Perhaps the moral is what my Grandma said, which was, “Kids, you can believe half of what you read, a quarter of what you hear … and an eighth of what you say.”
Of course, Grandma didn’t live to see the Internet. If she had, the percentage for believing what you read would have been much, much lower.
Oh, yeah, one final note … did I mention how much I dislike the current practice of “science by press release”? I suppose you gotta do it, it’ a competitive world, but my goodness …
So I guess the moral of this story is, “Never laugh at a climate science press release … you’ll have plenty of opportunity when (and if) the study is published.”
w.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Dear friend Willis Eschenbach,
The point of your post seemed to be that a 7420 km3 ice loss in 10 years is a preposterously high number. However, clearly it is plausible and reasonable.
The data in my plot was derived from the peaks in the same graph as your figure 3, and from the peaks in this http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.area.arctic.png graph. (If anybody can tell me a simple way to get the raw data for these source plots, that would be very helpful. I’ve been all over the NSIDC site and they seem to want to make it difficult.)
I can see that any further discussion hinges on whether or not one is convinced that AGW theory is correct, which you clearly are not. Therefore rather than waste time on discussing the future of the ice sheets, we should all go to a post dealing more directly with AGW theory as a prerequisite.
Besides, everyone else seems to have gone home!
Jbar, you asked about NSIDC data files concerning sea ice. Best I could do with a little wandering round their website is a set of ASCII files which can be ftp’d:
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Dec/N_12_area.txt
is an example which contains the historical records for sea ice in December in the Northern Hemisphere. Replace “Dec” with “Jan”, “Feb”, etc. and the “12” with the corresponding two-digit month index to get data for other months; and the “N_” with “S_” to get southern hemisphere data. I didn’t notice any consolidated files. More information about these files is available at
I copy/pasted the 12 months’ files for the Northern Hemisphere, and with a few clicks in Calc, produced
Note that these are monthly averages, so they will not reproduce e.g. which contains daily variation. Actually, there must be some other difference(s) as well, because the monthly average for the Sept 2007 minimum is given in the files as 2.78 million km^2, while the UIUC graph above just grazes 3 million km^2. For daily values, it seems that one must process images, e.g. those described by
Best of luck with finding the source data for that graph.
[mod — sorry, I ruined the links in previous post. Fixed, I think.]
Jbar, you asked about NSIDC data files concerning sea ice. Best I could do with a little wandering round their website is a set of ASCII files which can be ftp’d:
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Dec/N_12_area.txt
is an example which contains the historical records for sea ice in December in the Northern Hemisphere. Replace “Dec” with “Jan”, “Feb”, etc. and the “12” with the corresponding two-digit month index to get data for other months; and the “N_” with “S_” to get southern hemisphere data. I didn’t notice any consolidated files. More information about these files is available at http://nsidc.org/data/docs/noaa/g02135_seaice_index/index.html .
I copy/pasted the 12 months’ files for the Northern Hemisphere, and with a few clicks in Calc, produced this.
Note that these are monthly averages, so they will not reproduce http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.area.arctic.png which contains daily variation. Actually, there must be some other difference(s) as well, because the monthly average for the Sept 2007 minimum is given in the files as 2.78 million km^2, while the UIUC graph above just grazes 3 million km^2. For daily values, it seems that one must process images, e.g. those described by http://nsidc.org/data/docs/daac/nsidc0079_bootstrap_seaice.gd.html
Best of luck with finding the source data for that graph.
Jbar says:
May 30, 2010 at 5:00 pm (Edit)
I’m not following this, Jbar. You had said that your graph showed global sea ice. But you now say that you got the information from a graph of the Arctic sea ice, from Cryosphere Today.
If you go back to the Cryosphere Today page and look around, you’ll see a graph of global sea ice. It gives a very different result from your graph.
Huh? Whether or not we are losing huge amounts of sea ice is a factual question, one which is totally unrelated to my (or your) ideas about possible human influence on the science.
Why would you want to not discuss a factual question about the size of a phenomenon in favor of a question about possible causes of the phenomenon? First we have to determine the facts, before we can discuss possible causes.
Regarding sources, I’m in the same boat as you. What I do is digitize the graphs. Not the best, I know, but with care it can be done very accurately.
Willis Eschenbach says:
May 30, 2010 at 11:14 pm
Regarding sources, I’m in the same boat as you. What I do is digitize the graphs. Not the best, I know, but with care it can be done very accurately.
The CT data is available (see below), date, anomaly, area, 1979-2008 mean
Arctic area: http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008
Antarctic area: http://arctic.atmos.uiuc.edu/cryosphere/timeseries.south.anom.1979-2008
Global area: http://arctic.atmos.uiuc.edu/cryosphere/timeseries.global.anom.1979-2008
Phil. May 31, 2010 at 7:00 am –
Thanks! You’re a better web-detective than I am! Much appreciated.
Any idea why the UIUC figures differ from the monthly averages stored at NSIDC (cf. my earlier post at 8:03 pm)? Obviously the NSIDC’s figures are monthly averages, vs. UIUC’s daily values — but NSIDC’s averages are definitely not equal to the average of the UIUC numbers.
I don’t think it makes much difference in the end — both show quite similar trends — but as each poster has his/her preferred data set, I’d like to be able to translate from one to another.
Outstanding, Phil, that’s a superb find. Many thanks. I’ve looked all over the Cryosphere Today page for that data and never been able to find it.
All the best,
w.
HaroldW says:
May 31, 2010 at 10:44 am
Phil. May 31, 2010 at 7:00 am –
Thanks! You’re a better web-detective than I am! Much appreciated.
Any idea why the UIUC figures differ from the monthly averages stored at NSIDC (cf. my earlier post at 8:03 pm)? Obviously the NSIDC’s figures are monthly averages, vs. UIUC’s daily values — but NSIDC’s averages are definitely not equal to the average of the UIUC numbers.
I don’t think it makes much difference in the end — both show quite similar trends — but as each poster has his/her preferred data set, I’d like to be able to translate from one to another.
CT data is ice area not extent, extent will always be greater than area, closest in winter.
Phil, thanks for the reply, but I don’t think that’s it. The NSIDC monthly files contain columns for both extent and area, and I was comparing the area column to the CT data. For example, Sept 2007 monthly averages for the Arctic (from NSIDC file ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Sep/N_09_area.txt ) were: extent 4.3 MM km^2; area 2.78 MM km^2.
The CT data ( http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008 ) averages 3.02 MM km^2. [I might be off by a day or two in figuring which set of 30 days to average, but this would lead at most to an error of ~0.01 MM km^2.]
Hunting for more detail, I found that NSIDC defines their area calculation precisely at http://nsidc.org/data/smmr_ssmi_ancillary/area_extent.html . They use all pixels with an ice concentration of 15% or higher, multiply the area of each such pixel by the concentration in order to get ice area. They mention that their area does not include the “polar hole” above latitude 87.2 degrees, which represents around 0.31 MM km^2. [The polar hole changed in 1987 when they switched from SMMR to SSM/I; the 0.31 MM km^2 figure applies for July 1987 to present.] They describe two algorithms (“bootstrap” and “NASA team”) — the monthly averages cited above apparently derive from the “NASA team” algorithm. That same web page points to daily archives of Arctic sea ice area: “NASA team” at ftp://sidads.colorado.edu/pub/DATASETS/seaice/polar-stereo/trends-climatologies/ice-extent/nasateam/gsfc.nasateam.daily.area.1978-2007.n and “bootstrap” at ftp://sidads.colorado.edu/pub/DATASETS/seaice/polar-stereo/trends-climatologies/ice-extent/bootstrap/gsfc.bootstrap.daily.area.1978-2006.n
Unfortunately, adding 0.31 MM km^2 to the values in either file does not reproduce the CT sequence. So CT must have a slightly different calculation of sea ice area, which I’ve been unable to locate on their website. Since you managed to find the daily area values, I was hoping you also knew where they described their calculation of area.
By the way, NSIDC discusses the pros and cons of the two algorithms at http://nsidc.org/data/seaice/faq.html#2 , which has links to details of how the concentrations are derived from measurements.
“”” Using the data of (Cook and Vaughan, 2009), we delimited the area of five Antarctic ice shelves (Table 1), each on four separate occasions. Their combined area reduced from 33,416 km2 in the mid 1980’s to 14,098 km2 in the late 2000’s. “””
Wow! what astounding information. So we know the total area of five shelves (well delimited of course) to five significant digits; with no error bands; but we only know when that was so to within about 5 years ; say 1982 1/2 to 1987 1/2; and then that changed to less than half as much still good to five digits; but we don’t know when that was either to better than from 2005 to 2010.
So who was it said that Heisenberg’s principle doesn’t apply to macro things ? But perhaps it depends on what your definition of delimited is; or why delimiting makes a difference; and is it any different or de-differentiated from measured or calculated ?
I need a more up to date gobbledegook dictionary.
“”” wayne says:
May 29, 2010 at 10:18 pm
Dave Andrews says:
May 29, 2010 at 1:31 pm
Rocky Road,
“If all the world’s floating ice melted it would add about 4 centimeters to sea levels.”
I came across a study some time ago that said melting sea ice did indeed produce a very, very small increase in sea level. (Sorry I no longer have the source). It may amount to 4 centimetres if all the sea ice melted but, really, what are the chances that this will occur? “””
So how would that work ? The sea ice is fresh water; perhaps with included brine pockets. So it shrinks when it melts ( max FWD at 4 deg C); then it soaks up the salt from the brines and from the ocean and becomes even denser than just fresh water would be.
And then there’s that 80 cal per gm of Latent heat of freezing; which presumably would mostly come out of the ocean water that melted most of the ice; so that cools a whole lot of previously warmed sea water, which then should shrink.
The 2006 satellite results said the arctic ocen is falling 2 mm per year; well that was from about 1996 to 2006 when the ice was generally shrinking; so net melting.
But then barefoot girl didn’t seem too happy with the idea that most of that heat comes out of the ocean.
If she is right, and it all comes either from the air or the sun (maybe it melts before the sea temperature gets up to zero deg C.), then of course that shrinkage wouldn’t happen.
But four cm rise seems to me to be an astronomical sea level rise from melting all the floating sea ice.
“”” dr.bill says:
May 29, 2010 at 7:17 am
RockyRoad: May 29, 2010 at 6:27 am
They’re saying: “If all the world’s floating ice melted it would add about 4 centimeters to sea levels.” However, I understand floating ice displaces the same volume as it does when it melts, so whence the sea level increase?
Surface-level sea water has a density of about 1.025 kg/liter, so 1kg of it will fit into a volume of about 976ml. A floating 1kg block of fresh-water ice will displace the same 976ml, but when it melts it will need a full 1000ml. If you do the ice-cube-in-a-glass experiment with salted (or sweetened) water, the water will spill over (a little) when the cube melts. This is just another example of a technically real effect being blown out of proportion, much like the catastrophic 0.007°C (per year) of warming we’ve had over the past 100 years or so. Ho hum.
/dr.bill “””
But why would the melted freshwater ice remain fresh after it melts ? Any occluded brine pockets, which contain much of the salt that was expelled from the sea water when it froze; will be taken up by that water as it melts, and then mixture with the salty sea water; which itself should be saltier than normal by virtue of the extra salt that was rejected by the ice as it formed; should restore the original condition.
I suspect the actual change is a whole lot less than that 0.025 density change suggests. As the ice melted at the interface; resalinization of the newly melted fresh water, would likely keep pace with the melt rate, so I doubt that one would see much density difference due to salinity difference.
The whole process goes back and forth each year as the summer melt progresses followed by the fall/winter refreeze.
Willis-
Global annual min/ max is taken from Cryosphere’s global sea ice area plot, digitization as you say.
Arctic min/max is taken from the plot I linked.
Remember, I ONLY plotted the annual minima and maxima, so my plots won’t look like CTs.
There was no point in continuing with my thread because it would have concerned forecasting, which depends on whether or not one thinks there is AGW or something else going on.
Harold W and Phil –
AWESOME GUYS!!!
Looks like I have some work to do!
Monthly data is GREAT, with or without slicing and dicing.