By Steven Goddard
No matter what happens with the summer Arctic ice minimum, NSIDC will report that the long-term trend is downwards.
Why? Because of mathematics. In order to reverse the 30 year downwards linear trend, this summer’s minimum would have to be nearly 20,000,000 km². More ice than has ever been directly measured.
In other words, we could have a “Day After Tomorrow” scenario, and the mathematical trend would still be downwards.
Conclusion: You can count on NSIDC to continue reporting a downwards trend, regardless of what happens over the next few years. For now, it will be fun seeing what happens over the next eight weeks.
With a warm AMO and a previously warm PDO (now swithing cool), a downward trend in Arctic Sea Ice makes sense. The next few years though should be interesting to see the effect of a cooling Pacific. Regardless of this the Arctic is taking a beating this summer, certainly in terms of extent and should be awcknowledged by everyone who posts here. The causes however……………well that is a matter of debate.
Ian W:
Correct me if I’m wrong (the figure doesn’t have a label on the y-axis), but to the best of my knowledge one doesn’t need a baseline to make a linear regression. If you were to calculate anomalies, that would change things. So what do you really mean by your statement?
David L:
Of course one can use a linear trend for an interval of 30-ish years if the variations are sufficiently slow. Being a fellow scientist, you know that. Further, let’s consider an imaginary situation where you have a planet where ice *is actually* melting linearly. Would you still not use a linear regression, since one can not have negative values as time approaches inf.?
Even if there were a long-term downward trend in arctic sea ice extent (and there isn’t), it would be presumptuous and arbitrary to attribute it to man-made CO2 emissions. As the then alarmist Washington Post reported on Nov. 2, 1922, “The Arctic ocean is warming up, icebergs are growing scarcer and in some places the seals are finding the water too hot . . . Exploration expeditions report that scarcely any ice has been met with as far north as 81 degrees 29 minutes.”
Nature is simply running its course.
http://climaterealists.com/index.php?id=4861&linkbox=true&position=3
Archeopteryx
The data is the same data which NSIDC uses in their graphs.
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/
I’m surprised that anyone would find this post controversial. It is basic math. No matter what happens during the next few years, the “long term linear trend” will still be downwards.
Interesting mathematical study Steve…nothing related to climate of course, but a nice overview of statistical trends. Of course, NSIDC will report that the long term trend remains negative for Arctic Sea ice, as that is both the mathematical fact, and observational and factual truth. Climate is, afterall, a study of the long term trends, and how patterns repeat themselves over the longer term. If 2008 and 2009 had seen a recovery to well above 2007’s low mark, we’d all be having a different discussion right now. But, short of a sudden onset of global cooling, that would have been impossible. All that 2008 and 2009 did was level off from the rapid decline of 2007, but as the experts know, there really was no “recovery”.
I think the long term “tape” of anomalies in Arctic Sea ice is one of the most interesting graphs to study. Most of us here are quite familiar with it:
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg
It is rather like a EEG would be for a human. It’s little ups and downs are rather like the pulse of the Arctic. If you’re a trained physician, you can look at the EEG of your patient and know a great deal about the health of that patient. I think a trained eye, after studying the Arctic’s EEG, can spot the longer term trend. The trend that the NSIDC experts are all very familiar with. And something that few here may realize. We actually had a greater loss of ice in 2008 than 2007 if you look at the total volume loss from the winter peak to the summer minimum. That was remarkable, coming after such a dramatic loss in 2007. 2009 was not quite so large, but it certainly saw now great “recovery” of sea ice, and now here we are in 2010, and so far, as the “tale of the tape” in the link above shows, we’ve already lost the greatest amount of Arctic Sea ice from the March 31, 2010 peak through the end of June. As the tape shows, the drop has been dramatic. And now we approach July & August, the true heart of the melt season. Yes, wind and currents will play a role in the final exact number, but the trend is obvious, and any good “doctor” of the Arctic must look at the tale of the long term tape, and be concerned for the patient, realizing that if the trend continues, there will be some Arctic summer in the next few years or perhaps decades where the tape will flatline.
But is there a chance people will stop whinging about death spirals and “worse than we thought”?
Doubtful.
Quote Watts: “When you spend most of your time reacting you’ve lost the battle.”
Of course one could just ignore all the “science” that is promoted in various blogs. But then there is the question of spending the huge grants “”scientists”” receive. The actuall “”research”” isn’t time consuming enough. To make the budgets fit the grants, some time has to be spent by “”researchers”” reacting to “research”.
REPLY: Since you speak of ignoring, actually I think the best thing to do is ignore anonymous bloggers. As I’ve always said, if you don’t put your name to your opinion, it isn’t worth much. – Anthony
I guess it’s a phase shift. Temperatures stopped rising in 1997; instead polar sea ice began a downward trend. We’ll see whether it’s periodic or a one-off.
R. Gates
It is practically similar to an EEG for a human.
There, fixed that for you.
MikeEE
I think there is something very lopsided about looking at the trend of ice in the Arctic Basin. There is an upper limit to what the maximum ice can be since it is landlocked. I don’t know what that number is, but for any mean ice amount that is in the upper half of the area of the Basin, if the average annual negative deviation from the mean is larger than the area between the mean and the maximum possible area, then the trend will always appear negative in short time scales(<centuries?), as the positive deviations can only match the negative ones in small increments over a long time.
“As I’ve always said, if you don’t put your name to your opinion, it isn’t worth much”
So, why not just delete all posts under things that appear to you to be pseudonyms?
How do we know your real name is Anthony Watts?
“As I’ve always said, if you don’t put your name to your opinion, it isn’t worth much. – Anthony”
You can’t assess how good an analysis is, without knowing who wrote it?
I guess you’d have some trouble with a double-blind review process.
Anthony: If you won’t allow anonymous commenters, you’ll have to moderate about 98% of all your commenters. And Enonym could be my real name. I’m not from a country speaking anything that resembles english.
As for your statement “if you don’t put your name to your opinion, it isn’t worth much”, I have to dissagree, at least when it comes to asking questions.
I’ll stop commenting for now. That’s a promise.
Liers figure and figures lie (sometimes it’s not intentional, it just seems that way). Who knew. Guess the only thing to do when the range of data is sooooo small is to tell yourself that we’re unable to really claim anything trendy about the past few 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, etc., years. We want to know so much so fast we tend to jump to conclusions, usually, almost always, everytime…
Steve,
What is the purpose of this post? Are you trying to expose some kind of hidden agenda on the part of NSIDC in reporting a simple mathamatical fact?? Or are you trying to let your readers down gently about the reality of the Arctic ice melt??
Of course the linear trend in down–it just seems so simple when you tell it like it is without all the smoke and mirrors.
Keep up the good posts, they make for entertaining reading.
MJK
What is the correlation coefficient of fudged data point linear regression shown in this post by you know who? ~ZERO! ROTFLMFAO
Is there any point to calculating a linear trend in a chaotic weather system? In any physical model I have ever seen, one always asks, what happens at time infinity. If the answer blows up to something physically impossible, the model is hopelessly flawed. A linear downward trend in ice will shortly give us, Negative Ice!
A link from Antony lead to a very nice analysis of the physically meaningless global temperature.
http://www.uoguelph.ca/~rmckitri/research/globaltemp/globaltemp.html
One cannot take an average without first computing a sum. So it you have two pots of water, one at 300°K and one at 350°K, do you add them together to get 650°K? This has no meaning. The take away point is the “global temperature” has no physical meaning and only exists within the exact method of calculation. When Hansen refuses to release the codes and raw data, he is putting out numbers that can be anything he wants.
One wag had an excellent answer to someone’s question about how to get water to the moon. Just take Gore’s linear trend of twenty feet per century rise in the oceans and be patient!
Well doy! That’s because there IS a longterm downward trend…
This post is downright embarrassing.
How else can one fit a slope except by mathematics? What alternative is proposed?
Perhaps the slope is not what Steve Goddard wants it to be in June 2010? Well, that’s science for you. A theory undermined by a simple fact.
This blogger, Neven, finds the June daily melt rate has broken all records.
http://neven1.typepad.com/blog/2010/06/sea-ice-extent-update-7.html
Dave Springer says:
June 25, 2010 at 4:18 am
It appears to me from the satellite record there was no downward trend in arctic sea ice from 1979 to 1996 then in 1997 something happened that started a downward trend that lasted for about 10 years then leveled off.
CO2 emissions didn’t skyrocket in 1997 did they?
Hmm… what else can melt some ice? Anyone? Anything? Bueller?
Oh wait! Could this thing described in National Geographic Magazine do that?
It rose out of the tropical Pacific in late 1997, bearing more energy than a million Hiroshima bombs. By the time it had run its course eight months later, the giant El Niño of 1997-98 had deranged weather patterns around the world, killed an estimated 2,100 people, and caused at least 33 billion [U.S.] dollars in property damage.
How come rocket scientists can’t connect the dots here. No one else seems to have any problem with it.
The $64,000 question isn’t what caused the decline. The big question is what drives these gigantic cyclic ocean surface warming a cooling events. It sure isn’t CO2 as that has been on a very steady upward trend. It sure isn’t the global average atmospheric temperature inching up or down a tenth of a degree or two per decade as the 1997 El Nino made the ocean surface temperature in a huge swath of the Pacific shoot up 5 whole degrees above normal in a matter of months – more extra energy than “a million Hiroshima bombs”!
The answer, my friends, is NOT blowing in the wind. The answer lies deep down in the ocean. This makes abundant sense if and when a person comes to realize that the oceans hold 1000 times more heat than the atmosphere. The tail does not wag the dog.
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The answer my friend, is blowing in the solar wind,
with the synod conjunction of Neptune and Uranus being the 179 year base period to the medium cyclic period of climate natural variability, what we saw was the surge in warming manifesting as an El Nino , as a result of the Synod conjunction of N & U in mid summer, that drove the resultant peak in warming in 1998, now as these outer planets move into the later part of the year (fall this year) we will see surges in warm moist air masses at that time of year.
With the addition of Jupiter this September 22, I expect to see surges in tropical storm production from August 15th through mid October 2010, then a long quiet cold winter until the last week of March, before Saturn’s synod conjunction with Earth (April 3rd 2011) pulls in a warm surge of tornado producing tropical moisture to start the spring / summer off with a bang.
Being a 179 year period, we have very little records from the last cycle so this seems to be unusual, but it is all just a cyclic pattern. I expect the Arctic ice area to respond to the patterns that drive the global weather, and as these outer planets influence presses further into the winter seasons over the next 30 years, the resultant increase in winter precipitation will aid the long term “recovery of the lost ice”, as it cycles, as it does once again, but this time we will be able to watch it.
Since the NSIDC reports the sea ice extent to 7 or 8 significant figures, one thing is 99.999999 % sure, and that is with
the September minimum, is that the trend will change.
Somewhere around the 2009 minimum will be on the trend line, above that the trend will decrease and below that the
trend will increase.
How long will it take the current extent to cross and be above the 2007 line?
A couple weeks, a month, or never?
The current melt rate is cooking along pretty fast and steady.
Conditions have to change for the end of melt season result to not increase the trend, and soon.
At what point are you skeptics going to admit that the AGW proponents made a prediction that came to pass?
Douglas DC says:
June 25, 2010 at 6:05 am
What I do not get is the existence of Royal Navy records that show low ice extent at roughly the beginning of the Dalton. This has happened before. look at the location
of Viking Farms in Greenland. I think we hold ourselves in too high esteem for planetary destruction…
Would you care to explain the thrust of your remarks above?
So what if Arctic ice has been on a downward trend since 1979?–the Great Pacific Climate Shift from 30 years of global cooling to warmer occurred in 1977 so you would expect to see a downward trend since then. The critical question is what was happening to Arctic ice during the cool period from 1945 to 1977 and what happened during the previous warm period from 1915 to 1945? Greenland had more intense warming and higher temperatures during the 1915 to 1945 warm period and cooler temperatures during the following cool period. I don’t have the numbers but you can bet that Arctic ice increased during the 1880 to 1915 cool period, decreased during the 1915 to 1945 warm period, and increased again during the 1945-1977. Fluctations in Arctic ice is nothing new–it’s been decreasing and increasing with each climate change since 1880 and a decline since 1979 is what you would expect to see!
MikeEE says:
June 25, 2010 at 6:49 am
R. Gates
It is practically similar to an EEG for a human.
There, fixed that for you.
MikeEE
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Thanks, the simile is complete now…and the ghosts of our 5th grade english teachers can now rest in peace.
‘As I’ve always said, if you don’t put your name to your opinion, it isn’t worth much. – Anthony’
That was rather funny. What’s the opinion worth even when the name is supposedly known? Most opinions that doesn’t confirm ones own opinion is, of course, complete crap, and knowing the name just puts a face on that crap. :p