This is a repost of two articles from John Graham-Cumming’s blog. I watched with interest earlier this month where he and a colleague identified what they thought to be a math error related to error calculation when applied to grid cells. It appears now through a journalistic backchannel that the Met Office is taking the issue seriously.
What I found most interesting is that while the error he found may lead to slightly less uncertainty, the magnitude of the the uncertainty (especially in homogenization) is quite large in the context of the AGW signal being sought. John asks in his post: “If you see an error in our working please let us know!” I’m sure WUWT readers can weigh in. – Anthony
The station errors in CRUTEM3 and HadCRUT3 are incorrect
I’m told by a BBC journalist that the Met Office has said through their press office that the errors that were pointed out by Ilya Goz and I have been confirmed. The station errors are being incorrectly calculated (almost certainly because of a bug in the software) and that the Met Office is rechecking all the error data.
I haven’t heard directly from the Met Office yet; apparently the Met Office is waiting to write to me when they have rechecked their entire dataset.
The outcome is likely to be a small reduction in the error bars surrounding the temperature trend. The trend itself should stay the same, but the uncertainty about the trend will be slightly less.
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Something odd in the CRUTEM3 station errors
Out of the blue I got a comment on my blog about CRUTEM3 station errors. The commenter wanted to know if I’d tried to verify them: I said I hadn’t since not all the underlying data for CRUTEM3 had been released. The commenter (who I now know to be someone called Ilya Goz) correctly pointed out that although a subset had been released, for some years and some locations on the globe that subset was in fact the entire set of data and so the errors could be checked.
Ilya went on to say that he was having a hard time reproducing the Met Office’s numbers. I encouraged him to write a blog post with an example. He did that (and it looks like he had to create a blog to do it). Sitting in the departures lounge at SFO I read through his blog post and Brohan et al.. Ilya’s reasoning seemed sound, his example was clear and I checked his underlying data against that given by the Met Office.
The trouble was Ilya’s numbers didn’t match the Met Office’s. And his numbers weren’t off by a constant factor or constant difference. They followed a similar pattern to the Met Office’s, but they were not correct. At first I assumed Ilya was wrong and so I checked and double checked has calculations. His calculations looked right; the Met Office numbers looked wrong.
Then I wrote out the mathematics from the Brohan et al. paper and looked for where the error could be. And I found the source. I quickly emailed Ilya and boarded the plane to dream of CRUTEM and HadCRUT as I tried to sleep upright.
Read the details at JGC’s blog: Something odd in the CRUTEM3 station errors
Please fix this sentence:
What I found most interesting is that while the may error he found may lead to slightly less uncertainty
Thanks!
REPLY: Fixed. Thank you. One too many mays, that’s what I get for writing with a raging head cold. – A
Well hopefully the met is going to start again with tranparency this time. We shall see.
I would want a clear time line of when the subsets and their locations became the global set. Depending on oceanic/atmospheric conditions at the time, this could help explain the overall anomaly discrepancy between satellite and ground sensors in the NH as demonstrated in the Lean and Rind paper Leif linked for us.
Wow. So they can’t even get the math right, and yet they want the world to spend billions on a fix for a problem they say may be coming?
I think we should tell them where to go.
Anthony, I am at home too dealing with a raging head cold and solidly blocked up Eustachian tubes. But this gives me time to engage in my favorite website and my favorite topics.
REPLY: Just try to keep the CODE out of your nose – A
I assume the retraction of the sea levels rising has already shown up on your radar screen:
http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo780.html
REPLY: Yes story done here several days ago, thanks- A
Ha ha –http://bushynews.com/wp-content/uploads/2010/02/ipcc2.gif
It is pity the Met Office didn’t let JG-C know that he was correct. Instead he had to find it out from a journalist.
Fiddling with it at this end of the computation is all very well, but is it based on the raw data, value added or homogenised data.
In other words, more accurately computed rubbish is still rubbish.
why don’t they release the source code for the software, I’m sure WUWT readers will be able to help out with a bit of QA work.
The error bars are 95%, i.e. 2 sigma, the blogger hasn’t realized this and is just calculating sigma.
My pesonal take on Ben Santers latest rant on Real Climate.
I’m not quite clear on this. The error only affects the uncertainty range? What exactly does this mean?
One thing I do understand, yet again it takes a couple of “amateurs” to correct the pros backed by dollars and sophisticated equipment at the Met. Or am I making too much of it?
Mr Watts : With regard to temperature data, what is your response to Tamino, who has finished processing the GCHN data and subsequently now states :
“The claim that the station dropout is responsible for any, let alone most, of the modern warming trend, is utterly, demonstrably, provably false. The claim that adjustments introduced by analysis centers such as NASA GISS have introduced false warming is utterly, demonstrably, provably false.”
http://tamino.wordpress.com/2010/02/25/false-claims-proven-false/#more-2346
http://tamino.wordpress.com/2010/02/25/shame/
Is he correct in also stating that no-one else (particularly anyone who had doubt in that data) has done this to see whether there was in fact a real bias ? That can’t be true, surely ?
REPLY: I had a look, but reproducing will be rather difficult when he stakes stands like this:
Tamino’s response to request for code from Zeke:
It’s Jones’s “Why would I make the data available to you, when your aim is to find something wrong with it?” quote all over again. I’ve sent out messages to others involved, we’ll see if there’s any merit. -A
Is homogenization error a constant value for all stations, or does it differ by station? Graham-Cumming and Goz treat is as constant. I’m not versed in statistics, so any insight would be appreciated!
I am unclear how fixing an error can make the uncertainty ranges *smaller*. Wouldn’t it make them larger, as in, we’re now less certain?
[Response: I haven’t decided whether or not to publish this (peer reviewed). If I don’t I’ll probably make the code available to those who I consider serious investigators. That does not include denialists.]
Without being able to pass judgment on the technical merits in question, I would proffer the response that anyone who feels the need to continue using phrases like “denialist” is not operating as a scientist, but an ideologue. Based on this, I am prejudiced to suspect that when Tamino states that x is is “utterly, demonstrably, provably false,” he is either wrong or engaging in some kind of straw man argument. This kind of data should be part of the public record, period. AGW proponents can’t have it both ways. The more right they are about the potentially catastrophic consequences of warming, the more imperative it would seem that the data used to support the conclusion that warming is actually occurring are a matter of public concern. Therefore the more they practice this kind of selectivity and secrecy (which reminds one irresistibly of the ethical practices of immature Jr. High school students and their cliques), the less they deserve public confidence.
Oh good heavens Tamino. You are in need of a strong-tempered mother willing to put your stingy behind, after a good paddle, in a corner. Now share your candy. There is one word we mothers use for children who behave like this. Snot.
reproducing will be rather difficult
Why?
Reproducing Tamino’s results with the same data and the same code seems like it would be trivial, and not prove anything – unless you think he’s just flat making up his results.
The reference to Jones would be relevant if the data were private, but it’s not. Running those numbers should settle the question.
REPLY: The point is that I can or the main author behind this, E.M. Smith, can undertake a replication of his own. I’ve sent him an email and I hope he does. But reproducing exactly what “Tamino” has done would be difficult without his code. If its no big deal, and there’s no trade secrets or proprietary data involved, and as you say “trvial” why then does he offer only to share with people who might agree with his results and exclude others?
Do I trust “Tamino”, a man supposedly of science but who won’t put his name to his critcisms, who regularly denigrates others, and who now won’t share what he claims falsifies the work of people who do put their name to their work? In a word, no. -A
How good are former Geography students at software development for the HADCRUT code… ? (Tim Mitchell , missing tim Harry_read_me.txt)
http://www.cru.uea.ac.uk/~timm/personal/index.html
Tim Mitchell:
“At Oxford University I read geography (1994-1997, School of Geography). My college was Christ Church. At Oxford I developed a special interest in the study of climate change.
In 1997 I moved to Norwich to carry out the research for a PhD at the Climatic Research Unit (CRU) of the University of East Anglia. My subject was the development of climate scenarios for subsequent use by researchers investigating the impacts of climate change. I was supervised by Mike Hulme and by John Mitchell (Hadley Centre of the UK Meteorological Office). The PhD was awarded in April 2001.”
Of course if you get eco green evangelical christians students with a geography degree to write the HADCRUT code…?
“…Although I have yet to see any evidence that climate change is a sign of Christ’s imminent return, human pollution is clearly another of the birth pangs of creation, as it eagerly awaits being delivered from the bondage of corruption (Romans. 19-22).
Tim Mitchell works at the Climactic Research Unit, UEA, Norwich, and is a member of South Park Evangelical Church.
http://www.e-n.org.uk/p-1129-Climate-change-and-the-Christian.htm
What do you get (see for yourselves in in Harry_read_me.txt)
Even the scientists seem to want to Believe in AGW, rather than test for it experimentally, like John Haughton, they seem to want to belive that humans are polluting and destroying the earth. If you don’t look for the null hypothesis, you may not find the good news that AGW theory, may have a miniscule impact when compared to natural processes.
CRU provides one of three datasets (Hadcru) for OTHER researchers:
(we have since seen that the 3 are more interlinked than previously thought)
Tim Mitchell:
“An important part of my work is to develop climate data-sets. My intention is that these data-sets will then be used by researchers investigating the impacts of climate change. Here I provide access to these data-sets.”
CRU TS 1.2 10′ Europe 1901-2000 time-series pre, tmp, dtr, vap, cld MITCHELL et al, 2003 this site
CRU TS 2.0 0.5° globe 1901-2000 time-series pre, tmp, dtr, vap, cld MITCHELL et al, 2003 this site
(full list see the links)
http://www.cru.uea.ac.uk/~timm/data/index.html
http://www.cru.uea.ac.uk/~timm/data/index-table.html
There are three centres which calculate global-average temperature each
month.
•Met Office, in collaboration with the Climatic Research Unit (CRU) at the University of East Anglia (UK)
•Goddard Institute for Space Studies (GISS), which is part of NASA (USA)
•National Climatic Data Center (NCDC), which is part of the National Oceanic and Atmospheric Administration (NOAA) (USA)”
Tim Mitchell again:
http://www.cru.uea.ac.uk/~timm/research/index.html
I imagine an audit of the software development processes would be interesting to see.
If you’re going to do good science, release the computer code too:
http://www.guardian.co.uk/technology/2010/feb/05/science-climate-emails-code-release
Steve Mosher sums it up:
“So, I take a hard hard line on this. If you dont freely release your data and freely release your code in all cases then I am not rationally bound to even consider your claims.
You haven’t produced science, you’ve just advertised it.
The real science, is not the paper describing the data, its not the words describing the algorithm. the real science is the data AS YOU USED IT
and the code AS YOU RAN IT.
Pamela Gray (08:39:18) :
Anthony, I am at home too dealing with a raging head cold and solidly blocked up Eustachian tubes. But this gives me time to engage in my favorite website and my favorite topics.
Ah, this may explain why “Phil.” (http://deleted/) has suddenly sprung to the attack in the O’Reilly post after nearly exactly 24 hours (within six seconds, might have had a jumpy “submit comment” twitch). Like a jackal on the African plains, he sensed you were ill and weak, and decided to pounce!
I think the point is that if you hold down the button on the food processor long enough, everything is entirely uniform. Thereafter, it is impossible to backtrack to the roles of the various similar ingredients.
JGC and Ilya found gridding errors that varied improperly with the number of stations.
That problem was not masked by homogenization.
IHMO
RR
One does wonder at times why a public body, funded annually by the hard pressed British Taxpayer to the tune of £270M, with 1800 staff, with a new £30M XBox360 that does 2 billion calculations per second (allegedly) & a carbon footprint the size of a small town, housed in a state of the art green building just outside Exeter, Devon, should be having “errors” at all no matter how “small” considering that is appears to be a veritable idylic relaxed working environment! For that kinda money, I expect perfection! The same basic model that they use for 5 day weather forecasting is used for medium term forecasting & long term climate change prediction. If they get the weather wrong, what chance climate, but of course weather isn’t climate, its only, well, weather really, except when it’s climate!
Pamela Gray, I do hope you & Anthony get better soon!
What’s up with that chart. My eyes can’t focus on it. LOL. That’s a good way to hide errors…
I was thinking the same thing. It’s good to see that you openly put your name on this site, along with your credentials. I read through the comments on Tamino’s site, and not that it’s all cheer-leading. I couldn’t prove that opposing opinions are moderated out, but have a gut feeling they are.