Foreword: I had originally planned to post a story on this, but Steven Goddard of the UK Register sends word that he has already done a comparison. It mirrors much of what I would have written. There is a clear discrepancy between the two data sources. What is unclear is the cause. Is it differing measurement and tabulation methods? Or, is it some post measurement adjustment being applied. With a 30 percent difference, it would seem that the public would have difficulty determining which dataset is the truly representative one.
UPDATE: The questions have been answered, see correction below – Anthony
Arctic ice refuses to melt as ordered
Published Friday 15th August 2008 10:02 GMT – source story is here
Just a few weeks ago, predictions of Arctic ice collapse were buzzing all over the internet. Some scientists were predicting that the “North Pole may be ice-free for first time this summer”. Others predicted that the entire “polar ice cap would disappear this summer”.
The Arctic melt season is nearly done for this year. The sun is now very low above the horizon and will set for the winter at the North Pole in five weeks. And none of these dire predictions have come to pass. Yet there is, however, something odd going on with the ice data.
The National Snow and Ice Data Center (NSIDC) in Boulder, Colorado released an alarming graph on August 11, showing that Arctic ice was rapidly disappearing, back towards last year’s record minimum. Their data shows Arctic sea ice extent only 10 per cent greater than this date in 2007, and the second lowest on record. Here’s a smaller version of the graph:
The National Snow and Ice Data Center (NSIDC)’s troublesome ice graphThe problem is that this graph does not appear to be correct. Other data sources show Arctic ice having made a nice recovery this summer. NASA Marshall Space Flight Center data shows 2008 ice nearly identical to 2002, 2005 and 2006. Maps of Arctic ice extent are readily available from several sources, including the University of Illinois, which keeps a daily archive for the last 30 years. A comparison of these maps (derived from NSIDC data) below shows that Arctic ice extent was 30 per cent greater on August 11, 2008 than it was on the August 12, 2007. (2008 is a leap year, so the dates are offset by one.)
Ice at the Arctic: 2007 and 2008 snapshotsThe video below highlights the differences between those two dates. As you can see, ice has grown in nearly every direction since last summer – with a large increase in the area north of Siberia. Also note that the area around the Northwest Passage (west of Greenland) has seen a significant increase in ice. Some of the islands in the Canadian Archipelago are surrounded by more ice than they were during the summer of 1980.
The 30 per cent increase was calculated by counting pixels which contain colors representing ice. This is a conservative calculation, because of the map projection used. As the ice expands away from the pole, each new pixel represents a larger area – so the net effect is that the calculated 30 per cent increase is actually on the low side.
So how did NSIDC calculate a 10 per cent increase over 2007? Their graph appears to disagree with the maps by a factor of three (10 per cent vs. 30 per cent) – hardly a trivial discrepancy.
What melts the Arctic?
The Arctic did not experience the meltdowns forecast by NSIDC and the Norwegian Polar Year Secretariat. It didn’t even come close. Additionally, some current graphs and press releases from NSIDC seem less than conservative. There appears to be a consistent pattern of overstatement related to Arctic ice loss.
We know that Arctic summer ice extent is largely determined by variable oceanic and atmospheric currents such as the Arctic Oscillation. NASA claimed last summer that “not all the large changes seen in Arctic climate in recent years are a result of long-term trends associated with global warming”. The media tendency to knee-jerkingly blame everything on “global warming” makes for an easy story – but it is not based on solid science. ®
Bootnote
And what of the Antarctic? Down south, ice extent is well ahead of the recent average. Why isn’t NSIDC making similarly high-profile press releases about the increase in Antarctic ice over the last 30 years?
The author, Steven Goddard, is not affiliated directly or indirectly with any energy industry, nor does he have any current affiliation with any university.
NOTE OF CORRECTION FROM STEVEN GODDARD:
The senior editor at the Register has added a footnote to the article with
excerpts from Dr. Meier’s letter, and a short explanation of why my analysis
was incorrect.
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.
Click for larger image
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
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Ah, El Reg’s Mr. Goddard! Who is he, one may ask, as a “Steven Goddard” doesn’t even exist on the interweb before April 2008.
Geta loada that one, Steve! (I hope you got as big a yuk out of it as I did.)
Leon
Thanks for that. I had been following the graphs daily and was amazed to see such an ‘adjustment’! Really seemed to be an about turn.
Alan
Anthony
Well, I learn something new everyday. I turned those 14 .bmp files with 34MB total size into 14 .gif files of a bit over 320KB total size. Then my email automatically combined them into a self-extracting zip file. Hope you can make something out of them. Watching the battles of upticks/downticks is interesting.
Anthony,
Thanks for putting this up here.
The CT maps correlate pretty closely with the NSIDC extent maps. Both show the area where concentration is above about 15 or 20%. The reason I used CT maps is because they archive them every day, whereas the NSIDC maps are only archived once a month, and without a specific day of the month attached.
Numerical integration by counting pixels is a standard technique in image processing. Any error that is introduced is much less than the 45% difference seen in the latest imagery from today. No one can seriously argue that minor differences in pixel areas will account for this –
(BTW – I resent the insinuations that I don’t exist. Last time I checked, I was sitting in this chair typing.)
REPLY: I’ll add that I looked up the geolocation if the IP address from Mr. Goddards posting (WordPress provides them with each comment automatically) and it shows his location to be near Edinburgh, England. JohnA lives in the southern hemisphere now, though he lived in England last year.
So no more baseless accusations about Mr. Goddard’s identity will be accepted.
counters (15:19:01) wrote : “This is ridiculous. There isn’t anything scientific about this piece at all. Let me know when you’ve got an analysis that goes a tiny bit further than counting pixels on pictures… perhaps a mathematical analysis of recent years’ trends and their deviations from the mean ones, or an analysis of the methodology used by NSIDC to calculate their data? I’m not interestied in how many pixels are a different color on two pictures.”
counters, your knowledge of pixels seems to match you knowledge of climate change. You have a lot of bluster, but few facts. I use pixels day in and day out and believe me, you can obtain an accurate representation of a given area through a “head” count.
Jack Koenig, Editor
The Mysterious Climate Project
http://www.climateclinic.com
Wow, Goddard must have really hit a nerve with all the gnashing of teeth this one has provoked. Of course the pixel count is scientific, it is one of many plausible methods to determine ice area. As the article also states, the estimate is conservative due to the projection. Pixels at lower lattitudes represent more area than pixels at the pole. With a little spherical geometry applied this anaysis could be refined from the bounding case.
One of my professional activities is doing DNA sequencing using electron microscope images. Pixels of various brightnesses are counted and analyzed, to determine the location and type of chemicals present.
When dealing with micro or macro imagery, pixel colors and brightnesses are normally the only tool you have to work with. How else would you take satellite imagery and turn it into sea ice information?
Some of the vocal critics might want to slow down their mouths, and do a bit of thinking (for a change.)
A little off topic but all you pixel experts out there…..
I want to integrate an area under a complex curve I have graphed. It always seemed to me that you could do this by counting pixels. I have searched but cannot find one. Is there a program that you can input data for a graph, count pixels under a complex curve and thus find the area under a the complex curve (or a portion of a complex curve)?
REPLY: Yes, there is a program called ImageJ that will do that, so long as you fill in under the curve with pixels of a specific color that is different from the background. It was developed to do automated cell counts of microscope imagery by the National Institutes of Health. – Anthony
See features here:
http://rsbweb.nih.gov/ij/features.html
Jeff C,
I noticed that too. You would think there is a full moon the way they all came out on this one.
The whole article is completely worthless, as one would expect from an article written by a fictitious person. It doesn’t make a bit of difference whether this year’s sea ice extent is slightly more or slightly less than last year’s. The University of Illinois webpage cited in the article look has graphs of the sea ice area and sea ice area anomalies and see that the long-term trend is towards smaller sea ice extent year-round. And that’s what’s really important.
I’m not sure how “Steven Goddard” came up with his 30 percent difference claim. I counted the pixels, using NSIDC’s “Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data” data set and with a 15 percent criteria, and came up with about a 14 percent difference in the number of pixels with sea ice between the 2 dates. NSIDC is reporting sea ice EXTENT, not sea ice AREA, so in fact it’s quite possible that their 10 percent figure is correct.
REPLY: “The whole article is completely worthless, as one would expect from an article written by a fictitious person.” “Jeff” I take exception to this. Prove Mr. Goddard is “fictitious” or kindly stop posting your opinion about it.
“Jeff”….hmmm, who is that anyway? Since I don’t ahve a last name you must be “fictitious” right? 😉
Counters
I am a skeptic but, I do enjoy someone spicing up the discussion here. Sorry to see you knocked silly on the pixel comment. It is Friday and you might be a bit tired.
My question is I don’t see a comparison with the NIC IMS product. http://www.natice.noaa.gov/ims/
It shows the ice extend being much greater than the cryosphere pictures. Especially in the area around Eastern Siberia across to Canada. It shows much more ice. I have been looking at those pictures and comparing them. For example, compare the ice around Wrangel Island north of Eastern Siberia. In the latest NIC picture it is completely surrounded by ice. In Cryosphere it is ice free.
I assume they use different thresholds.
Apparently, the doubleplusungood deniers now tether on the brink of being declared unpersons.
I would, with all due respect, like to ask Mr Joseph Conrad if he has any factual comment on the relevant post, unless the inquiry itself is apt to render my humble self this perilous fate.
Alas! No oil money here! But questions remain, unless the asking itself leads to bitter oblivion!
In a Hansen Camp(tm) one could at least await one’s tribunal and the noose with head held high, but to be blotted out like the MWP at the whim of an acolyte? Nay! That is to much!
So if these are the stakes, I submit and humbly recant my heresy!
Otherwise, if it’s not objectionable, I’d really appreciate some enlightenment on the factual issues 🙂
How does the location of an IP address guarantee that the poster actually is at that location? What happens when someone is logged in remotely? The Register happens to have an office in Edinburgh.
Sorry for the snark earlier. I can’t excuse my tone on a couple posts this afternoon, so please accept my apology and I’ll work extra hard to dial it back a bit. I really could’ve used that cup of coffee this morning! 🙂
Look, all I’m trying to say is this: This is a serious allegation about the accuracy of a major repository of data. A thorough analysis which fully addresses the methodology of the NSIDC would only be a good thing. The problem is that publishing allegations in an online newspaper is not the proper way to get things done. I know most of you are skeptics here and I’m a “warmist” (although I prefer the less-pretty term “person who is sufficiently satisified with the data forming the basis of AGW theory and the mainstream conclusions in the field”), but maybe you can understand my frustration when every little allegation or comment going against the grain of AGW is jumped on. Skepticism is good and healthy; it’s important that people ask the hard questions and further the science.
But when an article such as this is posted, the situation changes. While many people will still keep focused on the important thing – verifying the methodology of the NSIDC – others will use this as another convenient one-liner as to why AGW is false. I can see the posts on DotEarth or WU now – “the NSIDC overestimates ice cap melt, therefore AGW is wrong”.
The bottom line is that when skeptics pursue issues such as this by engaging it in the popular media, a train wreck ensues. Allegations will fly about political motives; ad homs and poor debate will ensue on the blogs. If someone has serious concern with the methodology used to produce a major, then the appropriate channels of communication to be used are the scientific ones. Publish work demonstrating some sort of deficiency or discrepancy in the final products to a Journal, or contact the adminstrators of the product and voice your concerns. I simply can’t see how writing a newspaper column will do anything but fire up the noise machine on each side, and if there’s any doubt as to whether or not this is the ensuing reaction, I submit my own previous, inappropriate post as evidence.
Jeff (20:01:11) :
It’s possible, but what’s the gain? Hackers often use multiple levels of logins, even ethical users did that as long ago as the early 1970s on the Arpanet because one computer had a better net interface than the terminal servers.
Some unavoidable occur at large companies – I worked at a firm that allowed ssh access to the Internet. I live in New Hampshire, but the corporate firewall was in California. Something like that could well be the case, but why do you care so
much?
In order to compare CT maps vs. NSIDC maps, I made a video which superimposes the NSIDC map for August 14 on top of the CT map. As expected, it appears that they are nearly identical, though there are some odd discrepancies – like a small area NE of Svalbard where CT shows >50% concentration and NSIDC shows open water.
http://nsidc.org/data/seaice_index/images/daily_images/N_daily_extent_hires.png
Jeff –
“The University of Illinois webpage cited in the article look has graphs of the sea ice area and sea ice area anomalies and see that the long-term trend is towards smaller sea ice extent year-round. And that’s what’s really important.”
And I would add The South pole sea ice trend is toward a larger sea ice extent/area. Why isn’t that what’s really important?
Either way, it’s beside the point. Goddard’s article states that he sees a discrepancy between what is reported and what he observes. I commend you for checking into it yourself and more of us should be doing the same. Perhaps the difference lies in the definition of extent vs. area or different data sources. However the info from the Cryrosphere today does seem at odds with the NSIDC chart.
This is an article in an online journal that raises a question, not some “peer-reviewed” paper claining to settle the science. There are many smart people that are regular commenters here. Perhaps we can all do some auditing ourselves and figure it out.
IP address is not *all* that meaningful in determining someone’s location. It can in some cases (probably most) let you know where they’re posting something from, but it’s possible to post through a proxy or intermediary server and the IP you will get in that case, is the IP of the in-between server and not that of the original posting location. People use this to get around those web sites that only allow streaming content in the US by tunneling their requests through a US based server.
I don’t know who he is but it doesn’t really matter does it? I agree with the sentiments suggesting that the substance of the article is what matters.
I guess my only question would be… what does any of it mean? What do we mean when we talk about artic sea ice? Overall area? Thickness? area + thickness? Do satellite images in any way infer thickness of the ice? or is it just surface area? For instance, could the ice be wide and very thin and is that the same as a smaller thick area of ice? Certainly counting pixels will give you a count of some kind of real data, but I’m not sure what it actually tells you. Maybe someone can answer that.
All we really need is a valid measuring tool, and a consistent measurement (ie using the same reasonably valid methods) and a comparison of those same method’s measurements over time. Maybe that’s possible with some kind of satellite pixel approach.
Jeff C. (16:45:03) :
Wow, Goddard must have really hit a nerve with all the gnashing of teeth this one has provoked. Of course the pixel count is scientific, it is one of many plausible methods to determine ice area. As the article also states, the estimate is conservative due to the projection. Pixels at lower lattitudes represent more area than pixels at the pole. With a little spherical geometry applied this anaysis could be refined from the bounding case.
Goddard has made a mistake and his results disagree with all the published data. His mistake is probably because he is counting from the transformed data in the image rather than use the original data which can be downloaded? He and Jeff here appear to have a misapprehension concerning the projection used which is based on the secant at 70ºN not the tangent at the pole, which might be the source of the error.
“I can see the posts on DotEarth or WU now – ‘the NSIDC overestimates ice cap melt, therefore AGW is wrong’.”
I would analogize the evidence for CAGW to the evidence for alien visitation. There is lots and lots of evidence, but most of the time when you take a careful look at any one piece of evidence, it just doesn’t stand up to scrutiny. At which point, defenders of the faith are free to say “well maybe Crop Circle #1 is a hoax, but what about Crop Circle #2?”
It seems to me there’s a pattern here which seriously undermines the credibility of the warmists as a group. Of course, if warmists were better at thinking critically and admitting error when appropriate, the movement would have probably fizzled out by now.
NSIDC is reporting sea ice EXTENT, not sea ice AREA, so in fact it’s quite possible that their 10 percent figure is correct.
Jeff’s explanation seems highly plausible. Note this graph, from Cryosphere Today, which shows current area at c.4 million km2 –
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.jpg
By contrast, NSIDC’s graph of extent shows in excess of 6 million km2:
http://nsidc.org/images/arcticseaicenews/20080811_Figure2.png
So, Mr Goddard’s comparison is based on a basic error. Can we look forward to you clarifying this on your site, Mr Goddard?
A further point, Mr Goddard.You state that the NSIDC data “shows Arctic sea ice extent only 10 per cent greater than this date in 2007”. This is incorrect.
The August 11th announcement read as follows:
Arctic sea ice extent on August 10 was 6.54 million square kilometers (2.52 million square miles), a decline of 1 million square kilometers (390,000 square miles) since the beginning of the month. Extent is now within 780,000 square kilometers (300,000 square miles) of last year’s value on the same date and is 1.50 million square kilometers (580,000 square miles) below the 1979 to 2000 average.
http://nsidc.org/arcticseaicenews/index.html
Using those figures, I calculate the then current extent as being 13.5% greater than the equivalent 2007 date, bit 10% as you have stated.
The answer is the same reason all the TV weathermaps now show yellow for 60 degree temperatures — The map now looks all ” reddish and hot” to the naive viewer. If they had a disclaimer about the scale change, who would care — But they don’t. It’s clearly designed with a single intent in mind, try and convince people it’s getting hotter. Why they would want do this, I have no idea.
The ‘icy truth’ lies in the data processing software, I see no reason why the science group would not openly provide source code, and access to the raw pixel data. They could at least tell us what the change log looks like and explain any changes to the code. That would be good “open” science, instead of wasting people’s time trying to figure it out.
Something which is designed to fix just these types of problems … The U.S. has a law, Data Quality Act of 2001, this law requires federal agencies to ensure the integrity of the information they use and distribute. It also allows outside parties to petition to force the correction of information they believe is wrong.
The Data Quality Act (DQA) passed through the United States Congress in Section 515 of the Consolidated Appropriations Act, 2001 (Pub.L. 106-554). The Government Accountability Office calls it the Information Quality Act, while others call it the Data Quality Act.
This public law also applies to all Federal grantees, and all Federally funded groups.
Further note: the 13.5% greater figure I have calculated, as above, is of course remarkably close to Jeff’s recalculation of the pixel count, viz.:
I counted the pixels, using NSIDC’s “Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data” data set and with a 15 percent criteria, and came up with about a 14 percent difference in the number of pixels with sea ice between the 2 dates.
We seem to be progressing towards an explanation, which is simply that the discrepancy proposed by Mr Goddard doesn’t exist.
It seems wise to check over figures before leaping to a conclusion. That seems to me to be the proper scientific and sceptical approach.
counters
‘If someone has serious concern with the methodology used to produce a major, then the appropriate channels of communication to be used are the scientific ones.’
And I’m sure you were the first one to complain to IPCC about HOW new& improved “hockey stick” made it into their report.