By Steven Goddard
[see important addendum added to end of article ~ ctm]
[Note: The title and conclusion are wrong due to bias in the start/end point of the graph, the mistake was noted by Steven immediately after publication, and listed below as an addendum. I had never seen the article until after the correction was applied due to time difference in AU. My apologies to readers. I’ll leave it up (note altered title) as an example of what not to do when graphing trends, to illustrate that trends are very often slaves to endpoints. – Anthony]
JAXA Arctic Ice measurement just had its 8th birthday. They have been measuring Arctic ice extent since late June, 2002.
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
We normally see year over year ice graphs displayed in the format above, with each year overlaid on top of previous years. The graph below just shows the standard representation of a time series, with the linest() trend.
As you can see, Arctic ice extent has been increasing by nearly 50,000 km² per year. Over the eight year record, that is an increase in average ice extent of about the size of California. More proof that the Arctic is melting down – as we are constantly reminded. Spreadsheet is here.
How do we explain this? There has been more ice during winter, paralleling the record winter snow in the Northern Hemisphere. Meanwhile in the Southern Hemisphere, ice extent is at a record high for the date.
Size matters, but I’m guessing that Nobel Prize winner Al Gore didn’t share this information with his masseuse.
Addendum:
I realized after publication that this analysis is biased by the time of year which the eighth anniversary occurred. While the linest() calculation uses eight complete cycles, it would produce different slopes depending on the date of the anniversary. For instance, had the anniversary occurred in March, the trend line would be less steep and perhaps negative.
This is always a problem with graphing any cyclical trend, but the short length of the record (8 years) makes it more problematic than what would be seen in a 30 year record.
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EFJ Junior:
It would be best if you got off your high horse as to the trend because of the starting and ending points. It appears you haven’t read the note and the beginning of the article, nor the addendum at the end, which talk to this issue. Steve stated that if March were the starting and ending points, the trend would be different.
Steve, although some may say the following idea isn’t the best way to look at the data, I would be interested in seeing an additional 3 plots, that encompassed 7 years; one using the mid March (the ‘crests’ ) as starting and ending points, one using mid September (the ‘troughs’) as the starting points, and one using mid December of starting points. That to me would be an interesting way to look at the data, especially since it is only 7 years of data, as opposed to 20 or 30 years.
@ur momisugly EFS_Junior
Do you have a personal thing with stevengoddard? What’s the problem? He posted a article, recognized the error,(almost immediately) posted the error for all the world to see, and it is still there for all the world to see. It can be a very useful learning tool. What is it that you want? Should no errors ever be mentioned in history? Should we not learn from mistakes? Don’t you wish other people could be as forthcoming? Do you believe you are above learning? Or, is it something more cynical? Are you so blinded by your passions that you can’t see something positive here? Criticism can be useful, but useless criticism is wasted effort and indicative of the character of the person criticizing.
Why aren’t we discussing that 2010, having passed ALL other years . . . is now trending in towards 2007?
(or matching it, on 1 of the 4 Norsex charts)
It has been stated:
>> First week of July was 2007’s steepest Drop, it will be hard to match.
>> With Hudson Bay melt complete, 2010’s Plunge is flattenning out a bit .
The first is best seen on the NSIDC chart http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
The second … just look above at the JAXA chart.
PS: what is dissolved is NOT CO2 but Methane … it sort of fits inside Water Molecule patterns at certain temperature & Pressure combinations.
CO2 is not the ONLY Warming Gas: besides Methane – – the EPA career people & even Hansen have charged “Evil BLACK Carbon” – – or SOOT – – is responsible with MORE warming than CO2, due largely to the MASSIVE increases in Diesel Soot in Europe & Coal Soot in the Far east “the Asian Brown Cloud”. Drew Shindell creditted the Pair with 45% of Arctic Warming, almost twice as much as Global Warming (26%) contributed since 1974 – – and that is 26% for the average GLOBAL Warming, not AGW alone but
AGW ( “Smokestack Warming” + Deforestation +Fishing’s effects )
NATURAL Warming Cycles (increasing Sun + the “UP” half of the 60-year Pacific Cycle)
Random Variation …
…. the remaining 29% was the recent Sulfur cuts. (Sulfur is the “Great Global Cooler”)
Les Johnson says: July 2, 2010 at 4:32 pm
It might be interesting to plot the slope, as a function of month, or even, day of the year.
Is this what youre looking for? Linear trends added to each day of the year then plotted. Note that the early part of the year shows an increasing trend!
[http://] img267.imageshack.us/img267/8625/amsre20100628.png
a few days individually:
[http://] img338.imageshack.us/img338/4362/amsredaily.png
\harry
bob says:
July 2, 2010 at 3:06 pm
Ian H and R. Gates are correct,
“If you can’t do the math, get out of the kitchen.
Although the decrease in ice extent has slowed the last couple of days, 2010 still has a 482,343 square kilometer lead on 2007.”
Oops better make that a 420,000 sq kilometer lead on 2nd July. To quote Anu, the difference is dropping like a rock!! Given that over 200,000 sq km was lost on 3rd July 2007, and the average loss over the past 4 days has been about 70,000 I would confidently say the difference is going to be considerably less tomorrow.
James Sexton says:
July 2, 2010 at 6:17 pm
You should show Steve Mc. this “trick”and do a few Tamino studies with him.
Funny! Tamino talks a lot but doesn’t say anything. But I suppose some think he’s a cutting edge fellow. He’s like the baseball announcer on the radio that gets excited over a foul ball that he leaves the impression could be caught but it ends up 30 rows up in the stands. Dud excitement.
It’s so nice to read WUWT as I listen to Josef Hofmann on a Friday night at the end of a work week.
………….pleasant to be freed from the mediocre.
Steve & Anthony:
Very classy way to handle this. I’m being sincere. Despite our differences in perspectives, I can honestly say you’ve got more class and style than many on boths sides of the climate debate.
To turn a potential negative into a learning experience for everyone…Nicely Done!
@wayne July 2, 2010 at 8:17 pm
To “smooth out” the cyclic behavior, I’d suggest forming running averages over one complete cycle. This should help even if the data is not purely sinusoidal.
I just did that with the JAXA data, downloaded from http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv .
Some of the dates had a “-9999” indicating data not available. In a simple spreadsheet, these dropout areas were replaced by linearly interpolated data, giving the following plot:
http://img535.imageshack.us/img535/9863/arcticice.gif
A 365-day trailing average was then computed. The result: http://img155.imageshack.us/img155/3140/arcticicetrailingaverag.gif
That graph also contains a linear regression.
Just to be clear about what the 365-day trailing average represents: the final point of the trailing average graph, associated with 7/1/2010, represents an average of the daily values over the interval 7/2/2009 to 7/1/2010. That is, the 365 consecutive days ending on 7/1/2010.
Well, let’s see: An error was made, and quickly caught by readers and corrected quickly by the author. Steve even directly stated: “You are correct”. The first comment is at 1:55, and by 2:30 the addendum was posted, and Steve had already commented on it. The issue was fairly well dissected and corrections suggested. Yet, the faithful hope to seize on this momentary lapse and crush the deniers! Kill! 🙂
Someone refresh my memory, how long have we been waiting for a retraction of 200 ft rises in sea level? Ice free Arctic? Hot spot? Poley Bear extinction? Hellfire and Brimstone? This post is exactly what makes this blog credible, and it should stand proudly as such. It is honest and forthright. An error is noted, even by staunch skeptics, no matter who or what it favors. Get your truth here.
@EFS_Junior
Actually, this post is no more wrong than AGW theory and the entire works of the IPCC!
899 says:
July 2, 2010 at 5:41 pm
R. Gates says:
July 2, 2010 at 2:31 pm
Steve,
This article should be retracted, and I think you know it.
Why should it be? Where’s your ‘scientific data’ that empirically reveals that CO2 causes so-called ‘global warming?’
If CO2 were any kind of agent for ‘CAGW,’ then why –in the name of all that is good and proper– has it NOT caused all the ice to melt?
The polar regions ice have CO2 trapped within their frozen matrix, and heavens, there’s that virtually ‘flooded’ layer of air hanging just above the ice, which SHOULD make the CO2 DOUBLY effective!!!
But it’s not …
One would have thought that by now –what with all that Sunshine and CO2– that the ice would have melted, have become steaming hot, creating a veritable steaming expanse in the process!!!
But it’s not. WHY NOT?!?!!?
_________________
I don’t recall you being here before, but to possibly answer your question you’d have to know a bit about the difficulting of measuring climate sensitivity to changes in CO2 and then also a bit about chaos theory. Please display that you have the basic concepts down, and then perhaps we can have an adequate discourse.
You may want to start here, for some general background:
http://www.aip.org/history/climate/chaos.htm
http://www.abarim-publications.com/ChaosTheoryIntroduction.html
http://www.12manage.com/methods_lorenz_chaos_theory.html
In a nutshell, a system, such as the climate will attempt to maintain equalibrium, and even appear as a linear system, (i.e. you get a definite predictable change based on a known set of inputs). But of course, what we know is that the climate does not work that way, and that a system undergoing change, such as our atmosphere is now, with the addition of a historically and geologically large influx of CO2, may reach a tipping point where it suddenly and unpredictably goes into a whole new state of affairs. This is NOT a random event, but rather is deterministic, but is not predictable. I think if you read the above links, and the many others you can find on weather, climate, and chaos theory on the internet, you can get a grasp for why your questions in your post are a bit ignorant (not that you are, but the questions are).
Truly though, I suspect that you don’t really care what I answer with, and that you’ve already made up your mind that AGW is a bunch of nonsense propagated by ivory tower Professors or politicians trying to make a few billion dollars. This general thinking seems to be the norm among skeptics, and so, in general, trying to actually have an intelligent dialog is often quite futile.
@James Baldwin Sexton
Re: EFS_Junior
The politics of personal attack. It’s the number one tool in the leftist playbook. It got us B. Hussien Obama, which is the greatest thing in the world that could have happened–if you’re Jimmy Carter (he’s no longer the worst president in US history).
I think it is time to re-post the old swallow story:
The Swallow
When God created the swallow, a migrating bird that winters in Africa, He started to show him how to build his nest. He showed how to make small mud balls with his tongue and how to gradually build up the nest; but He was interrupted just before reaching the point where He started to show the swallow how the nest should get covered and have a roof. The swallow, half paying attention flexing its wings and ready to fly off swiftly after juicy flies and mosquitoes said “OK, OK, I know, I know” and flew away.
That is why swallows’ nests are only half built and they have to be under a roof or an outcropping. The swallow never had the patience to listen to the end of the demonstration.
As a child I often found myself in the swallow’s position, which is why my father would repeat the tale to me, mostly shortened to “remember the swallow”.
As an adult scientist I would hear his admonition in my head whenever I would rush to do something, where sometimes even angels would fear to tread, because of the excitement of a new idea. Had I behaved as a swallow at the needed learning stage?
Gee I love it when the (RealClimate ?) Trolls draw their swords and charge and suddenly find their credibility underpants round their ankles! At least they get to air their histrionics and righteous indignation even though the correction is done and dusted for all to see.
In contrast of course even the most qualified climate scientists don’t get that degree of courtesy at Real Climate to even mildly question propaganda or glaring errors in the science, maybe they should apply the same rigorous shouting at R.C. and see how they can improve that ailing site.
I must say that visiting that site was a revelation though and one of the reasons I prefer this site, and that of Joanne Nova for the quality of the scientific knowledge, and the level nature of the debate.
Keep up the good work and thanks for correcting and admitting mistakes – wish the others would be so candid!!
To Sod, R Gates and all the other typical AGW-friendly “gloaters”:
At least Goddard has the cojones to admit when he’s wrong.
Cut some bl**dy slack here. Geez-us!
Chris
Norfolk, VA, USA
Commenting to endorse the process, which, as others have noted, was a real-time example of the right way to do science:
Postulate
Reveal supporting data
Put it up for review
Listen to the feedback
Act on the feedback by changing the postulate
Rinse hands after wading through the ad-hom murk, and repeat
I applaud those who have commented in the spirit of real enquiry. Signal, not noise.
So what do all you experts make of this simplistic view of the same data (July 1st 2002 – July 1st 2010)? Noisy stuff; please explain the outliers.
Day-on-Day % Change = ((Ext[day+1] – Ext[day])/Ext[day]) * 100. Simples!
Surely it makes more sense to plot by month ? Annual average ice is about as meaningless as average temperature.
Monthly sea ice data here:
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/
Jan:
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Jan/N_01_plot.png
EFS_Junior, Ian H and R. Gates are the kind of people commenting that makes a non scientific person such as me veer towards being a “denier”. Their attitude coupled with what you can read about the IPCC and Climategate and now the Oxburgh report http://climateaudit.org/2010/07/01/oxburgh-and-the-jones-admission/ and the Hansen/GISS adjustments and so on really makes it more and more difficult to believe those that so heavily promote the AGW theory. I must admit that I lean towards the views exposed by the likes of Dr Spencer and Professor Lindzen that maybe around 20% of the warming max is caused by AGW. I wonder if they can understand why more and more people are sceptical when the various tipping point scenarios are given great emphasis in the press. The emphasis on the melting Arctic caused by CO2 and the ignoring of Antartic sea ice growth – just weather and circulating winds keeping warmth out or the ozone layer – but not climate and certainly not a sign that things may not be as bad as we should believe.
stevengoddard says:
July 2, 2010 at 3:57 pm
EFS_Junior
Read the top of the article now, and compare notes vs. the hockey stick decade long (and ongoing) stonewall.
WUWT corrects within an hour of publication.
stevengoddard says:
July 2, 2010 at 5:41 pm
wayne
“My error is much less egregious than Hansen, who chose a starting point at the bottom of one leg of a half cycle in 1979 to calculate his advertised trend of 1.7C / century.”
xxxxxxxxxxxxxxxxxxx
What a silly game of “My daddy is…”
We, WUWT publish retractions faster than….; if facing an inconvenient truth that is.
My error is not as bad as…., and that makes me feel better.
The alarmist’s stonewall has to be higher than ours; we never stonewall.
Our hockey stick has a crooked handle but plays true behind our hmm, stonewall?
I apologised; the other side never does.
When we apologise it is a virtue; the other side never apologises, they just stonewall.
R. Gates says:
July 2, 2010 at 2:31 pm
“And here I was going to complement you on getting the slow down in melting right after Hudson Bay melted so fast…and then you come up with something as rediculous as this.”
xxxxxxxxxxxxxxxxx
Short lived decline? 28/6 140,000 – 29/6 78,000 – 30/6 45,000 – 1/7 56,000 – 2/7 100,000 (KM2) Note; the 2/7 drop is the initial uncorrected number.
5 day average 28/6 to 2/7 is 83,000. Perhaps the arctic basin ice is of inferior quality as claimed after all. Interesting weeks ahead.
savethesharks says:
July 2, 2010 at 10:42 pm
To Sod, R Gates and all the other typical AGW-friendly “gloaters”:
At least Goddard has the cojones to admit when he’s wrong.
Cut some bl**dy slack here. Geez-us!
Chris
Norfolk, VA, USA
xxxxxxxxxxxxxxxxxxxxxxxx
Cojones? No. He had to.
“Cut some bl**dy slack here. Geez-us!”
Would that be reciprocal?
Good post Steve.
It certainly helps non scientists like myself understand the figures and the mistakes that can happen.
What I think has also arisen is a new breed of posters besides Trolls. These would be the ‘Snappers’, throw out a lure wait for them to circle and then reel them in one by one.
@stevengoddard
https://spreadsheets.google.com/pub?key=0AnKz9p_7fMvBdEdDTjFHWWtaSTB6NXBQQjVuNVQzWHc&hl=en&single=true&gid=0&output=html
Why is the fifth column of your spreadsheet titled Volume?
Thanks for leaving this up, warts and all. Being mathematically challenged, I learnt a little about the pitfalls of plotting trend lines from sinusoidal data. I wouldn’t have been able to do that unless the mistake had been made in the first place, and then discussed in open forum.
Kudos to Steven and Anthony for showing a little integrity and guts.