I had planned to do a post yesterday evening about how sea ice area and extent had returned to very near normal levels. But I was tired, so I saved off the graphs from the NANSEN arctic sea ice site.
This morning I was shocked to discover that overnight, huge amounts of sea ice simply disappeared. Fortunately I had saved the images and a copy of the webpage last night. Here is the before and after in a blink comparator:
There is no mention on the NANSEN website as to this change. So either it is an automation error or an undocumented adjustment. Either way, since this is for public consumption, NANSEN owes the public an explanation.
And there is more, see additional blink comparator graphs I’ve added below:
After examining the above, it appears the issue only manifests itself when comparisons to the 1979-2000 monthly average are made. The adjustment starting point appears to start around September 10th – at the summer minimum for both area and extent.
This could be a data processing error, though if so, it is so blatantly obvious to anyone who follows the NANSEN presentation that it immediately stands out. Many people commenting on this blog and others also saw the change without the benefit of my handy-dandy blinkj comparator above.
That fact that it occurs on a weekend could be viewed as suspicious due to fewer eyes on the website , or an indication that they have sloppy quality control there at NANSEN and this was published via automation with no human inspection prior to the update.
Steven Goddard writes via email:
The explanation (if one is offered) will be interesting to say the least.
UPDATE:
I received this email from Stein Sandven at Nansen in response to my query:
Dear Anthony,
The ice area calculation has been too high since about 22 October, causing too steep slope of the 2008 curve. We corrected for this yesterday and recalculated the ice area for 2008. The slope of the 2008 curve should now be correct and can be compared with 2007 and the previous mean monthly ice area.Best regardsStein
For my opinion though it seems to be an incomplete answer, generating even more questions.
I look forward to Nansen’s explanation. They can’t possibly expect make such a change without someone noticing. Or would they?
It does seem a bit odd however that this is occurring when Europe is loudly proclaiming its commitment to reducing emissions in order to “Save the Planet” from a relatively harmless gas.
Are the NANSEN team and the NSIDC team playing in the same “ball park,” or is one team playing in “Dodger Standium” and the other team playing in “Yankee Stadium?”
Ice growth slows; Arctic still warmer than usual http://nsidc.org/arcticseaicenews/
The period of very rapid ice growth that characterized October and early November has ended. The rise in ice extent over the past three weeks has been much slower, and should continue to slow until the expected seasonal ice extent maximum is reached sometime in March. Air temperatures over the Arctic Ocean stayed well above average during November, partly because of continued heat release from the ocean to the atmosphere and partly because of a pattern of atmospheric circulation transporting warm air into the region.
The period of very rapid increase in ice extent that characterized October and early November has ended. The rise in ice extent through the remainder of November and early December has been much slower.
(The paragraph concludes with this interesting sentence: The daily rate of ice growth has slowed simply because there is less physical room for ice to grow: the area of open water shrinks as ice fills it.)
“Air temperatures over the Arctic Ocean stayed well above average during November, partly because of continued heat release from the ocean”
The arctic ocen was practically completely frozen over on November 1. You can compare 2008 with 2007 here. I would like to know where this “heat release” was occurring.
And what actually limits the growth of ice is the sun. It is hard for either polar region to freeze much lower in latitude than where the sun reaches. We are now reaching the maximum extent of darkness in the arctic. Starting in January the rate of growth of ice will begin to decrease until it reaches zero at about the time all of the arctic is receiving some sunlight.
But this “adjustment” does reconcile one thing that had been bothering me. Cryosphere Today had been showing a half-million Km^2 negative ice anomaly in the NH while NANSEN had been showing about zero anomaly. This “adjustment” by NANSEN puts the two in closer agreement.
That was the point of my question last night
RH (19:04:15) :
Speaking of Arctic ice, there seems to be a discrepancy between http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic and http://nsidc.org/arcticseaicenews/. Is it just me?
Even though the time periods are different, 21 years and 28 years, the graphs looked to be too far apart. I could see some difference, but there were some higher ice years after 2000 before 2006 and 2007 to offset those years.
I suspected that NSIDC was not being accurate with their graph, but it might be Nansen that looked at the graphs more closely and had to correct an algorithm. Does the correction mean that they noticed the comment on this blog and made corrections? If so, it means this blog is serving a purpose and that some services are actually striving to be accurate and honest with the numbers they publish.
I think I’m accurate with this, but time will tell.
Ed Scott…..The daily rate of ice growth has slowed simply because there is less physical room for ice to grow:
Real:
http://saf.met.no/p/ice/nh/conc/conc.shtml
FM
What you [snip] fail to appreciate is that we have reached a Tipping Point ( named for Tipper Gore). Now all facts must be statistically modified.. Get with the program.
I saw that this morning too. I didn’t save any images but I am going to in the future. I look at the nsidc site every day and see how much the ice is extending beyond the orange median line. They removed the one in Hudson’s Bay. Good work Anthony!
This is unbloodybelievable!! I demand an explanation!
I’m no professional but the NSIDC chart flatlined for a week around the time Obama was elected! Was that a fluke? I don’t know. Quite possibly. Professionals please comment!
Now with the really cold temperatures it’s shooting up again. If it goes on for another week the same way it’ll hit the 79-00 average by Christmas.
There are clearly BILLIONS of dollars at stake here.
If AGW isn’t real, then Al Gore’s position at his mega VC disappears overnight. His credibility shot to pieces.
That’s a powerful reason to keep up AGW, wouldn’t you say?
Not saying it’s happening you understand, but being a skeptic in all forms, it’s always worth keeping an open mind……
There is no connection of any sorts to the presidential election – Anthony
In either case, 2007 is on a rebound! I’m wondering if the 2008 thinning helped the 2007 rebound by allowing the arctic ocean to cool off? Ice is a know insulator, as can be found on the internet
“Sea ice acts like an insulating blanket during the winter and prevents the
loss of heat from the relatively warm ocean to the much colder
atmosphere. When sea ice melts, leads and openings occur in the sea ice,
and in the Arctic winter, ocean heat flows into the atmosphere.”
In otherwords the arctic ocean / ice self regulates over decadal time scales?
“The period of very rapid increase in ice extent that characterized October and early November has ended. The rise in ice extent through the remainder of November and early December has been much slower.”
Ice extent Nov. 1: 8950000
Ice extent Nov. 12: 9673125
Increase: 723125
Ice extent Dec. 1: 10802813
Ice exten Dec 12: 11681563
Increase: 878756
(Data from the JAXA website)
I don’t think that is so very much slower.
Rhys Jagger says:
I suspect that his reputation is going to take a few more hits over the next year.
Blago sold it.
If the adjustment is 500 000 square kilometers (from the article headline), it is equivalent to 1.3 times the total land area of Norway.
I’d be hugely entertained, Dear Moderator, could I know why my 11:37:50 was subject to your revision. I believe the best thing about Wattsup is its shall we say “Open Mind”.
REPLY: I discourage use of that particular word, as it is offensive. If we snip it it posts where it is used that way, I should exercise the same diligence when it is used in other ways also. – Anthony
Did you have one of the charts manufactured in Denmark? 🙂
I noticed the change in the chart also this morning. As the ice extent reached the average suddenly the graph is changed without explanation. It will be interesting to find out why since only one side appears to be routinely involved with data manipulation.
The Arctic Summer ice melt is Al Gore’s primary example of global warming and one the public identifies with best (even though if all the floating ice in the world melted it would not raise sea levels). If he loses this example the credibility of his entire argument will be damaged.
Having earlier ice formation and more old ice should hopefully lead to a smaller melt next Summer.
11:37:50. Some places you can’t say McIntyre. Are you sort of like them? I don’t think so.
I’ll be patiently waiting to hear the explanation for this one. Nice observation.
I made a couple of overlay graphs showing Cryosphere Today area data vs. the Nansen data. It does appear that there was a discrepancy in the pre-December 11 data, which started around September 11. The newer Nansen data is generally more closely aligned to CT than the older data, though Nansen is now running significantly lower than CT since early November. In the December 10 version, Nansen was running consistently higher. Over the last month, the CT data was about midway between the December 10 and December 11 versions. You can see the overlays here.
http://temperatureadjustments.blogspot.com/2008/12/nansen-vs-cryosphere-today.html
As Anthony said, it would seem that an explanation is in order from Nansen.
Has the area graph been updated too?
I have some vague memory that ice within 5 miles of land was no longer going to be included in the total. Have they changed their definition of sea ice on us?
I’m confused.
Ice area was revised upwards, so instead of 500K sq. km disappearing, shouldn’t the headline be that it appeared overnight? Which is great news. But, yes an explanation is certainly needed for why.
Bruce Cobb (13:07:55) :
I’m confused.
Ice area was revised upwards, so instead of 500K sq. km disappearing, shouldn’t the headline be that it appeared overnight? Which is great news. But, yes an explanation is certainly needed for why.
You have it backwards sir.
The original graph had the ice level at a higher level, and right when we were about to reach the average level for the first time in years, they retroactively changed the data to be lower. The original graph was higher then the new one.
Fernando
“The daily rate of ice growth has slowed simply because there is less physical room for ice to grow:”
These are the words of the NSIDC. However, there is room for the ice to thicken. I found the statement of the obvious to be amusing.