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
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Even more interesting is the spread of this cloud from Aug 10-17.
Aug 10
http://satepsanone.nesdis.noaa.gov/pub/OMI/jpg/NHemisphere/OMI_NH_SO2_20080810.JPG
Aug 17
http://satepsanone.nesdis.noaa.gov/pub/OMI/jpg/NHemisphere/OMI_NH_SO2_20080817.JPG
Resolution of the image has nothing to do with the monitor. Most Image files contain a sequence of bytes representing the location, color, transparency and brightness of the pixel. The CT image files have a resolution of 850×850 which is 722,500 pixels. The calculations are done by software analyzing each of the pixels. You don’t need any monitor to do this analysis.
I don’t believe that anyone is doing anything intentionally wrong with the data. There is an inconsistency between the CT images and the NSIDC published extent numbers. There also is an inconsistency between the CT images and the CT area measurements – which are likely derived from someone else’s extent numbers. I’m keen to find out what the source of the discrepancies are. From comparing with satellite images, my sense is that the CT images are golden.
My beef with NSIDC is that they have a habit of taking spectacular stories to the press, which get misquoted and propagated in high places. They should take a more conservative approach to dealing with the press. They should also be more conservative in their predictions. Scientists should be careful to avoid the appearance of pursuing an agenda, as it potentially affects their objectivity.
Suppose that 2008 had of set another record melt. Why couldn’t they wait until September to discuss it, rather than making high profile predictions to the press in May? It is not normal behaviour for scientists to be so impatient.
Steven Goddard,
I don’t believe that anyone is doing anything intentionally wrong with the data.
I’m very pleased to hear that, and thank you for making that statement. You will be aware that many others on this thread have leaped to a different conclusion.
Suppose that 2008 had of set another record melt. Why couldn’t they wait until September to discuss it, rather than making high profile predictions to the press in May? It is not normal behaviour for scientists to be so impatient.
Their statement in May was:
Taken together, an assessment of the available evidence, detailed below, points to another extreme September sea ice minimum. Could the North Pole be ice free this melt season? Given that this region is currently covered with first-year ice, that seems quite possible.
I think that remains possible, FWIW, though I don’t think it would prove anything one way or another, and I wouldn’t bet on it. The concern is with a falling trend rather than what happens in a particular year.
It is possible that some scientists are “impatient” not because they are agenda-driven (not because they are part of a massive leftist conspiracy to raise taxes on the back of fake science, yada yada…) but because they are genuinely worried, on the back of their scientific understanding. Of course, they might be wrong, but I won’t personally object to scientists seeming impatient if their best judgment is that there are pressing concerns to address.
Steven Talbot,
“As I have indicated, I was naive enough to accept that Goddard’s statement was accurate. This confused me until you made clear that it could not be. Yes, I was insisting the data was the same source, since that was what Goddard had stated. My argument was proceeding from his stated premises.”
If you are referring to the data sources being the same, I did not make it clear that it could not be. I asked you for your evidence, since you had employed the assumption in a reasoned argument against Goddard’s claim.
This issue is still unresolved, but:
“Huh? The statement was “these maps (derived from NSIDC data)”. That seems a pretty clear process of interpretation to me, Glenn!”
is a quote mine. To use your partial quote from a previous post:
“A comparison of these maps (derived from NSIDC data) below shows…”
Again, it just isn’t clear whether Goddard meant that the comparison was derived from, or employed, NSIDC numbers, or whether he is claiming that the maps themselves are derived from NSIDC data. Nor should it be an issue of whether the same source of data was used for both.
“That may be reasonable in itself, but Goddard only applied this principle in comparing maps.”
I didn’t miss the point you claim is made here. The problem is that the maps are not the graph, and he was comparing the maps when he included a leap day. He could not have with the graph. You may be right that this favored a greater difference, but not a substantial one. Nit picking.
“Just as a graph is not a data source”
Now that is a hoot. Yes, Steven, graphs are sources of data. They aren’t satellite instruments, but representations of data allow data to be drawn from them. Were it not so, we should be thinking that we might as well be looking at cartoon reruns of Popeye. Data can reasonably be taken from the NSIDC graph, which is what I did, and resolution has little to do with quality here with respect to hundreds of thousands of square kilometers of ocean.
As to your claim about NSDIC data, your source reports for Aug 10, not Aug 11: “Arctic sea ice extent on August 10”, and if you look at Goddard’s archived graph of Aug 11, this year’s line drops a bit at the last day. That in itself makes your data from the NSDIC site and Goddard’s different by some amount. So aren’t you as guilty here as you claim Goddard is with respect to the leap day inclusion?
Steven Goddard,
Wouldn’t these U of Illinois maps be generated by an algorithm? Programs, or models, are only as good as the programming.
I share your concern for consistency in data, and from whatever source. Here’s just one other source that doesn’t match:
http://www.iup.uni-bremen.de:8084/amsr/amsre.html
So many different measurements leaves me with little confidence in any. I don’t want to accept this as good science. Global temps are shown down to
the thousanth of a degree, yet different sources vary tremendously more, almost as much as the claimed increase for the past 30 years. Yet that increase is only said to be a fraction of a degree itself. Hard to gain confidence in any, but especially hard with the sources that employ ground stations next to air conditioners. I see absolutely no responsibility shown by the AGW crowd.
This blog has put up two very different pictures of Antarctica temperature anomalies, both NASA origin it seems. Connolley believes the high-cooling one is the work of a “PR droid” (naturally) but I have other thoughts I put here.
More discrepancies in polar data? Any thoughts?
Glenn,
As for your first point, I think we must agree to differ in our interpretation.
Your second point, that I am nit-picking regarding the leap year offset. Perhaps so – one would have to consider the actual data for the day’s difference in order to know. But in any case, I thought that nit-picking about data accuracy was something people here thought to be important?
Now that is a hoot. Yes, Steven, graphs are sources of data. They aren’t satellite instruments, but representations of data allow data to be drawn from them.
No, Glenn, graphs are not the sources of data. They are representations of data, as you rightly say. The maps are also representations. Any representation may have inherent error, or may need careful interpretation, as is the case with the maps, evident from associated notes, for example:
Please note that our daily sea ice images, derived from microwave measurements, may show spurious pixels in areas where sea ice may not be present. These artifacts are generally caused by coastline effects, or less commonly by severe weather. Scientists use masks to minimize the number of “noise” pixels, based on long-term extent patterns. Noise is largely eliminated in the process of generating monthly averages, our standard measurement for analyzing interannual trends.
http://nsidc.org/arcticseaicenews/disclaimer1.html
You continue:
As to your claim about NSDIC data, your source reports for Aug 10, not Aug 11: “Arctic sea ice extent on August 10″, and if you look at Goddard’s archived graph of Aug 11, this year’s line drops a bit at the last day. That in itself makes your data from the NSDIC site and Goddard’s different by some amount. So aren’t you as guilty here as you claim Goddard is with respect to the leap day inclusion?
The comment and the graph were both archived on the 11th. Therefore, your point does not stand (i.e., the graph represents data to the 10th also). You simply underline the point that Goddard has compared data from different days!
I now have my new-and-improved sea ice area calculation. I did 2 things differently:
1) I limited the area to the “Arctic” by only looking for grid cells north of 63 degrees.
2) I assumed that the “pole hole” in the NSIDC data has more that 15 percent sea ice (a rather safe assumption)
I found 8467 grid cells with > 15 percent concentration on Aug. 12, 2007 and 9649 on Aug. 11, 2008. Since NSIDC also supplies a file with the area of each grid cell, I converted these to areas and came up with an area of 5523918 km^2 on Aug. 12, 2007 and 6281339 km^2 on Aug. 11, 2008.
I’m still at about a 14 percent difference.
REPLY: What was the rationale for 63 degrees N?
For Aug. 11-16, I got the following sea ice areas (in km^2) from NSIDC’s data:
6291339 6207404 6125202 6067534 5949942 5869797
This appears to show that the sea ice is still decreasing, though my understanding is that data less than 5 days old are subject to revision.
I’m trying to remember how I got started in this thread. One year changes in any quantity are usually not meaningful.
So many different measurements leaves me with little confidence in any. I don’t want to accept this as good science. Global temps are shown down to
the thousanth of a degree, yet different sources vary tremendously more, almost as much as the claimed increase for the past 30 years.
You might have a point if they were all purporting to be measuring in equivalent ways, but I am sure you are aware that they are not. The significant consideration is trend, and concern should be for the consistency of measurement within each set. Satellites, for example, exclude measurement of polar regions, the Himalayas and parts of the Andes, as I expect you know.
I see absolutely no responsibility shown by the AGW crowd.
Whereas I see that you’re happy to accept eyeballing a graph over calculating from raw data, accepting a pixel count of a mapped representation without assessing projection and disregarding the possible impact of spurious pixels, so long as it is supportive of the anti-AGW crowd?
The important point is not how this year’s minimum compares with last years record–on the log-term (by records standards, short term by geological or climatological standards.
The ice which is there now, is not the same as the ice that covered the Arctic 3,4,5 years ago–this ice is largely very young ice. It also has been frozen out of water with a lower salinity than previously, thanks to last years minimum.
These facts have implications such as: Lower salinity water freezes faster, younger ice is thinner and more fragile than older ice, so the ice will regrow faster as the salinity drops and the freezing point rises.
While last year’s minimum was exciting because of how little ice there was historically (a very short period in climate studies,) what was most noteworthy last year was that it was also the first time since the 80’s that the minimum dropped for three consecutive years below the long-term average slope.
The magnitude got most of the press, but it is the rapid increase in the rate of decline shown my the successive minimums which is of more concern.
If this year’s minimum manages to be above the long-term slope, then perhaps, there is no reason for excitement. If there is a fourth year in a row below that average, then the function describing the curve may have hit an area where the output of the physics has changed.
Frankly, basing any sort of reaction on such a small data point is an exercise in futility. The ONLY weather/climate predictions we can make that are reliable are for about 4 days in the future, getting excited either way because a prediction was right or wrong for this kind of thing is a valid as getting mad at the weather people because they said it would be a “normal” crop year and it was, except for that 2 week drought that timed just right to destroy the crop.
By its nature, we will be uncertain of what is happening with the climate long-term until it has happened.
Unfortunately, we MUST deal with the problems, permanent or temporary regardless of their duration.
There is no doubt anywhere, that humanity and the Earth will survive this kind of crisis–we habitate too many different areas to be easily wiped out.
But climate change will not kill us all the same way any more than overpopulation.
Next summer, baring major changes in current weather trends, there will be many placed in the Equatorial zone who will suffer drought and famine–they do not know or care if it is global warming, when you are thirsty and hungry, you only watn water and food. This is the kind of situation which historically has led to wars and toppled governments.
People faced with death tend to fight and the rules for fighting tend to go away.
Of course, at present, we probably can feed and water nearly everyone we do today–If we are willing to do so. This may not remain true for more than a few months.
It is also possible, but looks less likely, that the patterns could shift, the monsoons return, the droughts recede.
The US SouthWest has lived for over 100 years knowing that they cannot sustain the lifestyle. Now they are in a major drought, but major droughts are historically common in that area, and they have often run for decades and in at least once case into centuries.
The US SouthEast is also in a drought, that is not historically a normal pattern since settlement.
In the Midwest, our rain and snow belt has shifted south by about 100 miles from 30 years ago, we are now edging to the other of our 2 modes in Western Wisconsin: we’re drying enough to edge to being prairie after a couple hundred years at least, of being forest.
Using different models, difference measuring systems and differing algorithms to determine ice cover does obscure the subject and makes comparisons difficult to impossible, but there is no standard, recognized measure for ice coverage, and there is no 100% reliable algorithm to calculate. Remember that te original data used for calculation is very likely different in quality or dates, and even a small difference in how the program determines if pixel is ice or not could result in major varations.
The difference between 10 and 30 % additional coverage seems significant, but given the experimental error in making the measurements, it may well be with observational error.
The most important point of all seems overlooked:
In the past 60 years we have learned that the “stable” planet upon which we live is not stable at all, and gradually we have learned that the large events of the past which we have been unable to nail down to within a century or two in many places, do not necessarily take 10’s 100’s 1,000’s or more years. Instead, we find increasingly that very large changes can happen in timespans considered short by individual humans–under a decade perhaps.
Many of these changes are drastic enough to greatly damage our civilization. Some in the past have been enough to threaten our species.
Such events seem to have happened in the past on a semi-regular cycle, and we have identified some things with cycles of orbital change and axial tilt, others appear to have no causative factor–mostly because we are probably very short on data.
Can melting the Arctic cause an Ice Age? Many of our models, which we routine trust on other matters, say yes, it can. Our experts agree that it is “unlikely”–but use the model to predict other climate changes.
What I know is that I know of no system, natural or designed which behaves according to a smooth function at all times. And I am CERTAIN that no system which involves positive feedback can remain a smooth function.
The fastest glacier in the world is moving at 300 feet per day. We have no idea how fast they are capable of moving (the fastest clocked avalanche was 250mph) If the East Antarctic ice sheet started moving that fast, it would dump many, many cubic kilometers of ice into the ocean, which, coming from land, would displace their mass in seawater, raising the sea level.
We know that the faster a glacier moves, the more cracks it develops, and the more cracks the more melt water gets to the bottom, the more water, the faster the glacier.
Similarly, methane release from sea floor methane hydrate has been strongly implicated in at least one major extinction event. A major release could easily trigger enough warming to cause more releases.
Round and round she grows..the story of positive feedback.
Is the climate changing? Probably. What route will it take? We can only try to predict and make educated guesses. Will it cost us to attempt to slow the now apparent changes? Yes. But the real question is: How much will it cost us if we fail to act and or predictions come true? That is the question which determines how much we need to invest in insurance and that includes efforts to slow or stop the change.
The main possible events I see as possible, in order of desirability:
1) The Arctic ice melts and triggers a mini-ice age, reversing the warming trend enough to bring us back to a climate which is close to what we consider “normal.”
2) We have an asteroid, meteor shower, or comet hit us, or volcano which is large enough to affect the climate and small enough not to devastate us.
3) A limited nuclear war. Recent calculations from 2007 show that a limited nuclear exchange would have similar climatic effects to a full MAD scenario.
4) The melt continues, when Greenland has lost about 1/2 of her ice, the West Antarctic sheet breaks free and slides into the Pacific. This combination raises sea level around 7 meters. Warming continues and the East Antarctic Sheet begins to accelerate and drop hundreds of cubic kilometers of ice each season into the sea–perhaps eventually a single very large event.
5) The methane hydrate melts and accelerates the melting of other such reserves and we have an extinction level event similar to 55 million BCE.
I favor 1-3 because they are the scenarios which cost the least number of lives.
#4 is survivable for the civilization in a drastically altered form, as a large percentage of our population would die. #5 would stand a good chance of destroying our civilization, if not the species.
At this point, our simulation model, Project 6, says that #3 is most likely, and sometime next year. Depending upon harvests and the US foreign policy among other factors.
The disadvantage of foretelling the future is not in being wrong, but in being right and unable to stop or change the outcome.
Steven Goddard
“I’m keeping a running count of 2008 vs. 2007 from the full resolution (850×850) CT maps. August 15, 2008 shows 41% greater extent than August 16, 2007.”
Using the actual data, I get a difference of about 13.6 percent.
Glenn
“You lost me there, Jeff. The number of pixels IS resolution. And i fail to understand how “larger on a monitor” is relevant. Your monitor bigger than mine, or what.”
If after a snowstorm I were to measure the snow depth at 1 kilometer intervals and then interpolate the data to a 100-meter resolution grid, would that be the same as measuring the snow depth at 100-meter intervals?
Steven Talbot,
Hopefully you are aware that alphanumeric characters are only representations of data as well, and not the true source. Recording, reproducing and representing data can all suffer from error. Sheesh, even the data source can and and often does contain error. That doesn’t mean that a graph isn’t a source of the data used to create it. Again if that were so, graphs would not be used. Some representations are better than others, of course. Your complaint seems to be rooted in the belief that these graphs and maps are error ridden. If so, then it would be immoral to publicize them. Your claim that graphs aren’t data sources is not believable, since you realize that they are representations of data.
As to the graph and your quote from the NSIDC page, all I know is that archiving is done when it is done, that the graph itself is said to be updated daily online, and when I read “On Aug 10th…” I take it that the event described is represented as having occured on that date. The graph URL is dated Aug 11 and is Goddard’s reference, and the data you used to falsify his conclusions was said to be from Aug 10, and resided on a separate webpage. Clearly you used different data.
Compare last year’s sea ice on this date with today’s sea ice: click [this page takes a few seconds to load].
I prefer looking at the maps rather than engage is this endless true believer nitpicking. So, who are you gonna believe? The maps of sea ice, separated in time by exactly one year? Or your lying eyes? Personally, I believe what my eyes tell me. Others have their religion to guide them.
And this whole discussion centers around the Northern Hemisphere. Note that the Southern Hemisphere has significantly more sea ice than in previous years. Added together, global sea ice is rapidly increasing. Inconvenient, huh?
Steven Talbot,
“You might have a point if they were all purporting to be measuring in equivalent ways, but I am sure you are aware that they are not. The significant consideration is trend, and concern should be for the consistency of measurement within each set. Satellites, for example, exclude measurement of polar regions, the Himalayas and parts of the Andes, as I expect you know.”
The significant consideration is accuracy, my friend. You are right that there are different methodologies for measuring, and comparisons should only be made with data measuring the same thing(s). Yet different methodologies should generate the same data, since the reality is that there is only one Earth and one “global temperature”. If you feel comfortable will all this inconsistency, I think you are being just as irresponsible as the experts who generate it. If I hire two people to come into my house and make termperature measurements, I expect they will both arrive at the same result, or both be considered wrong and their data discarded. I’m puculiar about *measurements* that way, and science is or should be especially so.
Me: “I see absolutely no responsibility shown by the AGW crowd.”
“Whereas I see that you’re happy to accept eyeballing a graph over calculating from raw data, accepting a pixel count of a mapped representation without assessing projection and disregarding the possible impact of spurious pixels, so long as it is supportive of the anti-AGW crowd?”
Excuse me, but I’ve offered no conclusions beyond the maps being inconsistent with the graph. This can not be seen as being supportive of anything other than consistency. Regardless, it appears that the Arctic melt is largely if not exclusively a result of events not related to “global warming”, so for me this issue has nothing directly to do with being supportive of the “anti-AGW crowd” or critical of the “AGW crowd”.
But making claims about what I “happily” haven’t done or have disregarded, in the absence of evidence of that, isn’t quite honest. It’s a tactic I expect from an AGWer. Are you one, or rather do you accept the “projections” made by the various AGWers that spell doom and gloom if we don’t all stop drivin that hot rod Lincoln?
Steven Goddard (11:52:39) :
Phil,
You keep describing the NSIDC map projection (ad nauseum,)
Three times!
which is not the one that CT uses in their maps
According to you, although CT uses the NSIDC data which is archived in the polar stereographic format that I described.
and not the map set that I used. Rather, I used the CT maps which are higher resolution than the NSIDC maps, have more detail, and are archived every day. No matter how many times you describe the NSIDC projection, it doesn’t have any impact on this discussion.
As I have attempted to explain to you before, the CT projection is the view of an astronaut 10,000 miles over the North Pole.
Elementary trigonometry shows us that that is not the projection that CT uses! (hint the earth’s radius is 3963 miles)
The only point which is undistorted is right at the pole. As you move away from the pole, the distortion increases approximately as the sine of the latitude. (At 30 degrees latitude, a pixel would represent 2X as much area as one at the pole.)
I guess trig isn’t your strong point! (30º isn’t visible on the CT map either, although it would be if they used the projection you claim.)
Glenn
“I’ve offered no conclusions beyond the maps being inconsistent with the graph.”.
Ignoring the data is a tactic that I expect from an [snip- you don’t get to use that word here]. NSIDC’s graph is consistent with the data. I’ve posted the location of the data, so you can do your own count. NSIDC’s graph is also consistent with the “recent ice area” on the CT website.
The only “evidence” to support the “conclusion” that NSIDC’s graph is inconsistent with the maps is someone’s claim to have counted pixels on re-projected images created using an unspecified algorithm (actually, there were likely multiple interpolations. NSIDC sea ice data is stored in polar stereographic grids. I’m guessing that the data first had to be interpolated to a lat-lon grid and then interpolated again into the image space).
Personally, I tend to believe objective data rather than someone’s guesstimate. But to each his own. Some people prefer to believe that what they believe is true. Then again, when a friend showed me the maps I guesstimated that there was about a 15 percent difference. Maybe my eyes are just better calibrated than most peoples’.
Smokey
“Added together, global sea ice is rapidly increasing.”
Really? You know this from where? You certainly didn’t find this out from the “Global Sea Ice Area” graph on the CT site.
Charles
‘At this point, our simulation model, Project 6, says that #3 is most likely, and sometime next year. Depending upon harvests and the US foreign policy among other factors.’
And, of course, your model incorporates as many of the forecasting principals as possible as laid out in the Principals of Forecasting hand book. If not your model is nothing more than a reflection of your guestimation.
Anthony says in reply to counters (15:19:01)
Using the color scale provided, and its corresponding RGB value, it is an easy and certain mathematical exercise to turn those pixels back into real data, with no loss, no rounding, no floating point error.
Not so sure about that. I tried my own pixel count (using the Python image processing library). There are difficulties with the UIUC daily images as the map colours do not match the scale too well. This might be due to colour distortions from JPEG compression, or some other image processing artifact. It would certainly help if Steven Goddard explained his method in more detail so someone else could reproduce his results.
To quantify of my own visual impression, I also tried the even less scientific method of using the free select tool in the Gimp image processing app to outline the ice extent, then measuring the selected area. The result surprised me – 20080817 was only 17.5% above 20070818. Just eyeballing the images I would certainly have expected a bigger difference.
REPLY: Be careful how you save the image from the website. Doing it the wrong way can add an extra level of JPEG compression (from whatever tool used to save it) and may make the image far worse thatn the original. An image saved once with JPEG compression, but saved again as a bitmap image or other lossless format will only have one level of JPEG compression, and often that compression is reversable. – Anthony
If this story gets 1% the coverage the original alarmist story got I will be shocked.
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.
What does make a difference is whether or not NSIDC is accurately reporting the data.
It also makes a difference if there is a strong reversal in trend, even if it is only over the course of a year. Especially as it coincides with outside factors such as PDO and AO reversal.
As to what direction the trend takes from this point we simply don’t know now. In the meantime it would be awfully nice to be getting a correct graph of ice extent from government agencies.
Dipole,
Remember Goddard’s comparison is for a specific time, Aug 11, not the 17th.
Anthony replies to my previous post (22:39:44)
Be careful how you save the image from the website.
I am using wget from the command line (on a linux system), so I assume I have an exact copy of the image on the uiuc site. I suspect the colour distortion is introduced by whatever software uiuc use to produce the image.
REPLY: Ok that should be a good save then. I’ll point out that even with distortions, you can still delineate the colors used for ice from open sea to get the total number of pixels representing areas of sea ice @ur momisugly 15% or greater… the hues differences, even with distortion introduced by JPEG compressions should be easy enough to capture and turn into pixel counts.
I didn’t run this experiment, Mr. Goddard did, but that is how I think he approached it. Correct me if I’m wrong.