Guest post by Willis Eschenbach
A few days ago, Steve Goddard put up a post called “Does PIOMAS Verify?” In it, he compared the PIOMAS computer model estimate of the Arctic ice volume with the SIDADS satellite measured Arctic ice area. He noted that from 2007 on, the two datasets diverge.
Intrigued by this, I decided to compare the PIOMAS ice volume dataset with the Cryosphere Today (CT) Arctic ice area dataset. Here is that data:
Figure 1. Arctic ice area (red line) from Cryosphere Today. Black line is a 6 year Gaussian average.
When I compared the two datasets, I expected to find something curious happening with the PIOMASS dataset. Instead, I found a puzzle regarding the CT dataset.
I compared the CT area dataset with the PIOMAS dataset, and I found the same thing that Steve Goddard had found. The datasets diverge at about 2007. So I took a hard look at the two datasets. Instead of an problem with the PIOMAS volume dataset, I found the CT area dataset contained something odd. Here is a plot of the CT daily data with the daily average variations removed:
Figure 2. Cryosphere Today daily ice area anomaly. Average daily variations have been removed.
The oddity about the data is what happens after 2007. Suddenly, there is a strong annual signal. I have put in vertical black lines to highlight this signal. The vertical lines show the end of September of each year. Before 2007, there is only a small variation in the data, and it does not have an annual signal. After 2007, the variation gets large, and there is a clear annual aspect to the signal. The area in September (the time of minimum ice) is smaller than we would expect. And the area in March (the time of maximum ice) is larger than we would expect.
I considered this for a while, and could only come to the conclusion that there was some kind of error in the CT dataset. So I decided to look at another dataset, the NOAA SIDADS dataset.
Again, I removed the monthly signal, leaving only the anomaly. Here is that result:
Figure 3. SIDADS monthly ice area anomaly. Monthly variations have been removed.
Again we see the same oddity after the start of 2007, with a large annual variation where none existed before 2007. In the SIDADS dataset the variation is even more pronounced than in the CT data.
So that is the puzzle. What has changed? Are they using a new satellite? If so, has the changeover been done properly? Since the smallest of the data has gotten smaller and the largest of the data has gotten larger, is the average data still valid? Just what the heck are we looking at here?
Despite searching, I have not been able to find the answer to this question. However, I have great faith that the assembled masses of the WUWT readership will find it very quickly. (And then some of the readers will likely tell me that this shows I am a layman and a fool, and that I should have been able to find the answer easily on my own … so sue me.)
Isn’t the scale wrong on Fig 2 and 3? If it’s anomaly it should be between + and – 3 million?
When it’s graphed properly like here
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg
then it becomes more obvious that since 2007 it’s been slower to recover and faster to get melting presumably because it’s thinner. The final maximum ice extent in winter is little changed. I guess the question is whether this is a reaction to 2007 or part of the long term cycle. Many pro-AGW people seem to accept that 2007 was an exception that stood outside the long term downward trend. Why shouldn’t the recovery from that exception also.
I thought short termism was dangerous.
long term cycle
should read
long term trend
(that darn Freud!)
Interestingly enough, total sea ice extent, Arctic plus Antarctic still stays remarkably constant. I still think there could be a hypothesis that something is making this happen. What exactly, I have no idea whatsoever. It does not surprise me that after the dramatic loss if ice in 2007, that something like an annual signature has developed. This merely goes to show, that, like what is currently happening magneticly to the sun, there is an awful lot in science that we simply do not understand.
Kevin Cave says: June 1, 2010 at 3:47 am Could it be that what we’re seeing in the graph is not as a result of large temperature fluctuations, but rather, large swings in Arctic wind patterns which might be caused the current extended solar minimum? Just a thought.
Seems most likely to me. The 2007 minimum area in the arctic was wind and currents not temperatures. Interesting if solar activity affects the polar wind and/or currents.
Good observation Willis.
Well two NOAA sat.s was decomissioned in 07. One new was put into operational status that same year which is now primary AM. The primary PM was upped last year.
The graph do look some what odd at the end if one considers that newer tech ought to give higher resolution and that that should show up in the statistics as well. From your graph it looks like the resolution dropped like someone emphasized the highest and the lowest and smoothed out the in between. Of course when using less precise stuff one ups the resolution by taking more points, so maybe they just don’t have to take as many points with the new primaries. And they probably do update their software as well with time.
I am a skeptic, but I agree with Nigel’s interpretation. If the Arctic is going to melt in the summer, it will re-freeze in the winter, and the intra-annual variation will be higher.
Tenuc says: June 1, 2010 at 6:32 am
1410-1500 cold – Low Solar Activity(LSA?)-(Sporer minimum)
1510-1600 warm – High Solar Activity(HSA?)
…………..
Expressed in the most simplified form, it appears that the sun activity has a regular cycle of high and low activity:
http://www.vukcevic.talktalk.net/NFC5.htm
Peter Ellis says:
June 1, 2010 at 6:25 am
Here you have the yearly melt curves for 2007/8/9 and also the average across the historical record. The anomaly is the *difference* between the average and the actual yearly data.
Sorry, even you and N others above can also be wrong. Seems Willis is politely searching for the answer to a question. He clearly described what he was showing in those two charts above. Just go and look up the word “anomaly” please, your Wikipedia will do:
“An anomaly is any occurrence or object that is strange, unusual, or unique.”
His two chart were “unusual”, so he told you, exactly where, why, and how he made them.
Is that ICE a guy WHO came, or is it ICE THAT came from the cold?
However we know there is somebody behind…these wet things, some bedwetter…
Steve Fitzpatrick says:
June 1, 2010 at 5:45 am
Increased winter ice extent with falling summer extent just doesn’t make physical sense. If there is increased open water area in the summer months, then solar heat accumulation in the Arctic Ocean would increase, and so tend to delay the formation of winter ice, not promote it. More likely there is some change in how the data is being processed that causes an increase in the reported seasonal variation.
—————————–
Steve, I disagree with what you are saying here. There is nothing in the data processing that has changed in recent years. And there are several institutions showing the same thing.
While it is true that the ocean must first release the heat it gained during summer before it can refreeze, freeze up rates have been quite fast during autumn once that happens. And all you require is a thin ice cover for the extent to go back up. So even if the ocean is warmer than it used to be, a thin layer of ice can still form in winter resulting in a larger seasonal variation.
In fact as ice cover thins in winter, the standard deviation in the September ice extent goes up. This makes sense since thin ice is more vulnerable to atmospheric circulation variability. At some point however the ice becomes too thin to survive summer melt and that is when the Arctic becomes more like the Antarctic.
but even if we ignore changes in variability, it is clear from the data that the trend in winter ice cover is small whereas the trend in summer ice cover is large. Thus, that would naturally result in larger seasonal variation. 2007 was incredibly anomalous in terms of its summer ice cover, and hence the fact that seasonal variability increased at that time is no surprise at all (and note it is smaller since then reflecting more summer ice cover in 2008 and 2009)
I think the abnormal blowout of floating ice in 2007 is the culprit. Deep dive, then quick refreeze, but ice was thinner/younger, then it melted rather quickly in the summer and so on. But the multiyear ice extent should increase, if the summer minimum will go up.
Steven Kopits says:
June 1, 2010 at 6:53 am
I am a skeptic, but I agree with Nigel’s interpretation. If the Arctic is going to melt in the summer, it will re-freeze in the winter, and the intra-annual variation will be higher.
*
*
That doesn’t make sense, for it presumes an offset differential.
Thanks to toby (June 1, 2010 at 6:27 am) for providing that clip of Dr. David Barber of the U. of Manitoba. What I found most interesting about that clip is confirmation from a scientist in the field that satellite data may be giving data that should not be trusted. (In Dr. Barber’s clip, it was that his ship was able to sail along at a speed of 13 nautical miles per hour, which is about what it would be able to do in open water, in an area where that shouldn’t have been possible if the ice had been what the satellites were saying it was: thick multiyear ice.)
If we can’t trust the data, how do we proceed? Get better data!
According to my wife (who knows such thing) when a system moves in the direction of
least resistance the amplitude/volatility goes up. Thus, increases in arctic ice are the
natural bias of the cryosphere from where we are today. That is, it is easier for the ice to increase than to decrease. Expect rapid rises and slow declines.
Anthony,
I recall that CT had to recalibrate its sensor because the data was over estimating the ice LOSS. No attempt was mad to repair legacy data to reflect the repair. Also afterward there seemed to be greater “gain” in the variation , as you put it, greater annual variation. I emailed CT 2 years back but they did not respond to me.
During the first deep minimum ~ 2007, CT sent out an email saying they has problems with the data. They never tried to explain it more than that.
There is something going on in the way the area is calculated, and there is serious doubt that the entire data set was generated using the same rule and calibration. In fact I am certain that rather than a contiguous data set, the plot should be broken into discrete data sets identifying the boundary when the recalibration and software change were made. Good luck getting that kind of discipline from the sandal sporting “experts”.
Paul
The northwest passage opened up briefly in 2007 and 2008. Guys were driving their power boats through it. I’m guessing all the exhaust fumes upset the entire arctic region. Yeah, that’s it. That’s the ticket.
The same thing may have happened in 1906 when Roald Amundson made the first successful passage right before it froze back up for 100 years. They didn’t have power boats but they had cookstoves, campfires, and they all smoked tobacco. The moral of the story is don’t blow smoke up mother nature’s ass.
In 1999, Don Easterbrook predicted that a 30 year global cooling period would begin within a few years because of the change in the Pacific Decadal Oscillation (PDO).
See:
WHERE ARE WE HEADED DURING THE COMING CENTURY?
Consequently, I reject David Gould’s prediction of the Artic being ice free by 2014, and vote with Willis.
Willis,
I thought this paper had some interesting insights to recent ice thickness,
http://www.agu.org/pubs/crossref/2010/2010GL042652.shtml
also
http://arctic-roos.org/observations/satellite-data/sea-ice/total-icearea-from-1978-2007
The anomalies on the arctic roos website look a little different especially in the ‘recovery’ in 2010.
It’s perfectly possible to get the post-2007 data.
2007 was the minimum of minimums, meaning that for the next few years, a large amount of young ice, more susceptible to subsequent melt, would be formed each winter.
If you say that the next two winters were colder than normal in the arctic waters and seas, then you can easily get higher winter maximums, but with that ice being thin, a large melt would still happen.
Now it appears that there is more thicker ice this year, that change may start to drop a little.
Time will tell.
Tenuc says:
June 1, 2010 at 6:32 am
Providing the data hasn’t change to any significant degree, my guess would be that the changes are caused by ocean current thermal lag effects and changed wind patterns. Both of these being effected by the transition from a highly active to a quiet sun.
Perhaps this change will lead to a recovery of Arctic sea ice, which has been in decline since the start of the 80′s. We do not have a sufficiently long record of sea ice cover to know whether this is a new phenomenon or not or how it relates to longer term climate quasi-cycles.
1410-1500 cold – Low Solar Activity(LSA?)-(Sporer minimum)…..
_______________________________________________________________________
You forgot the Norse not to mention the Romans. The Norse were seafarers and they hunted on the seas, so they were aware of the sea ice. Here are the Greenland temperatures from Ice Core data The temperature at that time was 2C warmer than today.
“…..When the Norsemen arrived in Greenland, they had the island and its waters to themselves. Now they had to contend with the Inuit, who were competing with them for animal resources. This was especially true in the Nordseta, the Greenlanders’ traditional summer hunting grounds 240 miles north of the Eastern Settlement. For years the Norsemen had been traveling to the area; they killed the walruses, narwahls, and polar bears they needed for trade with Europe and for payment of Church tithes and royal taxes. They also boiled seal blubber, filled skin bags with the oil, and gathered valuable driftwood……Upright stones divided the cow stalls; a whale shoulder blade (white partition on right) also served as a divider…” http://www.archaeology.org/online/features/greenland/
“…The settlers found that the area to the north of the Western Settlement, called the Nordseta, was good for hunting, fishing and gathering driftwood. A stone inscribed with runes has been found telling that in 1333, three Greenlanders wintered on the island of Kingigtorssuaq just below 73 degrees north. There is also evidence of voyages to the Canadian arctic. Two cairns have been discovered in Jones Sound above 76 degrees North and two more have been found on Washington Irving Island at 79 degrees north….” http://www.mnsu.edu/emuseum/prehistory/vikings/Greenland.html
For you information Washington Irving Island is at the entrance to Dobbin Bay, eastern Ellesmere Island, Nunavut, Canada. See the map and notice this area is well within the arctic circle and not that far from the north pole (about 600 miles) and certainly within the Beaufort Sea Gyro.
Detailed Chronology of Late Holocene Climatic Change: http://academic.emporia.edu/aberjame/ice/lec19/holocene.htm
An interesting description of Norse habitation of North America plus a Norse map of the arctic area, north pole islands and all: http://www.heritage.nf.ca/exploration/norse.html
I believe the annual variation since 2007 is real and will damp out over time. I suspect that it is due to the loss of a large amount of very old thick ice in 2007. That is the sort of ice that stands up well to summer conditions. After 2007 we are left with a smaller inventory of “old” ice and it must be built up again. It takes 5 years to make 5 year old ice. I would not expect inventories of old ice to return to “normal” until roughly 10 years after the anomaly. So basically it takes 5 years to make the first new 5 year old ice and about 5 more years of that to come to some stable inventory of it.
I would expect to see that annual signature to damp out over about a 10 year period. It should be simple math. In 2007 you look at the inventories of 1,2,3,4, and 5+ year old ice and you watch the old ice inventory build over time until they are back to something close to what they were.
Old ice is important to maintaining summer ice cover as older ice has had more of the salt worked out of it and it is fresher. That gives it a melting point at a higher temperature than fresher sea ice with a higher salt content. The unusual loss of old ice in the 2007 event removes a sort of “flywheel” effect that the old ice provides.
“New” ice will melt somewhere around -2C whereas “old” ice melts closer to 0C and two degrees of difference is huge in the Arctic. The more old ice you have, the harder it is to melt it.
JJB:
“While it is true that the ocean must first release the heat it gained during summer before it can refreeze, freeze up rates have been quite fast during autumn once that happens. And all you require is a thin ice cover for the extent to go back up.”
I think you are missing the point. It is the increase in extent of winter ice at the same time that the summer minimum extent is falling that makes no physical sense. Sure, a more rapid decline in summer ice is consistent with thinner ice, tipping points, etc, etc. But a more rapid summer decline most certainly is not consistent with increasing winter ice extent: more heat absorbed by the ocean does not logically suggest more ice formation, it suggests less. Observations that appear inconsistent with simple concepts like energy balance should be critically examined for accuracy, not immediately accepted at face value.
Wow, how many people here share my initials? I’ve changed my name for a second time to avoid confusion. Might have to start using my full name soon, but Greenpeace already know where I live, so, you know..
How do 31 years of satellite measurements (and less than a decade of accurate ones) make a ‘trend’, a ‘tipping point’ or a ‘death spiral’? Even if as some have asserted / wildly speculated, the summer Arctic does become ice-free by 2014, why, particularly in the light of early 20th century observations of severe Arctic melt, and longer term proxy observations of temperature oscillations on a millennial timescale, should that be taken as unusual, let alone support of an AGW hypothesis? Satellite observations might be useful as an observational tool, but using them as a basis for prediction and modelling from an insignificant sliver of data goes beyond clutching at straws. It is no surprise that people who deal with these observations for a living (or an obsessive hobby) might imbue them with more significance and predictive value than they actually hold, but really, I am in a better position to make alarming pronouncements on ‘tipping points’ in the global economy having looked at three minutes worth of stock market graphs, especially, to further the metaphor, with my vague and incomplete understanding of the economics involved.
Willis,
This is very interesting. I want to point to something quite off topic that I may have missed at this site on previous posts. That is, your presentation at the ICCC 4 conference was BRILLIANT! I could not attend so I have been watching the videos at Heartland.org. Yours was easily one of the best presentations I’ve watched. Bravo, sir!
Joe Lalonde says:
“Another thing is that our species CAPTURES and holds water when no other species had in the past and this is TRILLIONS of gallons a day.”
Not even beavers?