I’ve been away from WUWT this weekend for recovery from a cold plus family time as we have visitors, so I’m just now getting back to regular posting. Recently on the web there has been a lot of activity and discussions around the issue of the dropping of climatic weather stations aka “the march of the thermometers” as Joe D’Aleo and I reported in this compendium report on issues with surface temperature records.
Most of the station dropout issue covered in that report is based on the hard work of E. M. Smith, aka “chiefio“, who has been aggressively working through the data bias issues that develop when thermometers have been dropped from the Global Historical Climate Network. My contribution to the study of the dropout issue was essentially zero, as I focused on contributing what I’ve been studying for the past three years, the USHCN. USHCN has had a few station dropout issues, mostly due to closure, but nothing compared to the magnitude of what has happened in the GHCN.
That said, the GHCN station dropout Smith has been working on is a significant event, going from an inventory of 7000 stations worldwide to about 1000 now, and with lopsided spatial coverage of the globe. According to Smith, there’s also been an affinity for retaining airport stations over other kinds of stations. His count shows 92% of GHCN stations in the USA are sited at airports, with about 41% worldwide.
The dropout issue has been known for quite some time. Here’s a video that WUWT contributor John Goetz made in March 2008 that shows the global station dropout issue over time. You might want to hit the pause button at time 1:06 to see what recent global inventory looks like.
The question that is being debated is how that dropout affects the outcome of absolutes, averages, and trends. Some say that while the data bias issues show up in absolutes and averaging, it doesn’t effect trends at all when anomaly methods are applied.
Over at Lucia’s Blackboard blog there have been a couple of posts on the issue that raise some questions on methods. I’d like to thank both Lucia Liljegren and Zeke Hausfather for exploring the issue in an “open source” way. All the methods and code used have been posted there at Lucia’s blog which enables a number of people to have a look at and replicate the issue independently. That’s good.
E.M Smith at “chiefio” has completed a very detailed response to the issues raised there and elsewhere. You can read his essay here.
His essay is lengthy, I recommend giving yourself more than a few minutes to take it all in.
Joe D’Aleo and I will have more to say on this issue also.
rbateman (07:32:06) :
“You have been going on for days about all stations do the same thing, and you are wrong.”
I’ve never said that. Please go up and down this thread. You will never see a time where I said that. This is important to understand, too. Trends differ somewhat as you go around the world. Arctic different from tropics, Antarctic Peninsula different from East Antarctica; there are regional differences. Just make a trend map at the GISS page and you can see it.
The point is, if you drop stations such that the average trends for that particular gridbox don’t change, *then* dropping stations doesn’t have much impact. From the multiple analyses, adding up all the grid boxes, we see no major difference in the global number; you can use the current ~1200 stations and get the same results, pre-1990, as using the full set. But if you had a gridbox that had stations of all different trends, and you somehow sat there and selected out all the fastest warmers or slowest warmers or whatever, then you could bias the results. But that simply isn’t what happened.
Amino Acids in Meteorites (07:16:56) :
You said to stick to science. Please do.
Paul Daniel Ash (10:48:20) :
He hides his work and resists FOI. Why would a scientist do that? Unless he has something to hide.
Paul Daniel Ash (10:48:20) :
I am not attacking the man. So it is an attack to tell people he is an environmental activist that doesn’t like people to know his methods with temperature data?
Am I lying? Am I exaggerating? No, I am not. He has made this bed for himself. Now he is sleeping in it. I did not do these things to him.
Paul Daniel Ash (10:48:20) :
“Tamino…… huh, who exactly is ‘Tamino’?”
……………………………………………………………………………………………
Well, no one knows who he is.
So, who is he?
I am asking who he is. I am not the one concealing his identity. Blame him. Makes sens to blame him, doesn’t it?
Jan Pompe (10:18:05) :
I agree with you that it doesn’t matter what the person does in their personal life. I don’t have a problem with that at all.
What is the problem is all the secrecy. The secrecy leaves one asking a lot of questions. If he was forward to have everyone look at everything he does at his government paid job then he would avoid all these suspicions.
But since he is an environmental activist and global warming is a political and environmentalist issue it can make one wonder what is really going on behind the scenes.
It is not like he doesn’t have a history with politics and environmentalism. To say that is not an attack. I am sure these things about him have to be taken into account in trying to ascertain why he is secretive. How could they not be? If it turns out he has a legitimate reason in relation to science as to why he makes things so difficult then one could disregard his personal views. But his stubbornness makes me have serious doubts about the purity of his motives.
Am I being unfair?
carrot eater (15:53:55) :
Stick to the science. You are right.
The science shows that there has been no statistically significant warming since 1995. The science shows there has been cooling since 2005. It also shows the ‘manmade co2’ level continues to rise while no warming is happening. The science shows co2 is a small player in climate and does not control temperatures. Science also shows that there can be no runaway warming caused by co2.
The science shows climate models ‘perform poorly’.
http://www.scribd.com/doc/4364173/On-the-credibility-of-climate-predictions
‘….computer climate model outputs not matching observation…’
http://www.scribd.com/doc/904914/A-comparison-of-tropical-temperature-trends-with-model-predictions
Amino Acids in Meteorites (18:52:57) :
“Am I being unfair?”
It’s not really a question of fairness truth isn’t the slightest bit interested in whether it’s fair.
If a person who is responsible for data makes due diligence impossible with his behaviour that of course needs to be addressed the proverbial blowtorch to the feet might be appropriate.
We due however need to be careful being an activist could be a result of what one believes he is seeing or it can colour his vision. His data might be perfectly OK if we toss it out because all we see is activist so we trust him are not then also the losers?
My point is where due diligence is applied as it should in all cases where 3rd party data is used then it is just an unnecessary distraction.
Jan Pompe (21:48:53) :
the proverbial blowtorch to the feet might be appropriate
LOL! Thanks for the laugh.
And I agree, due diligence is what matters.
AAiM.
With respect to your comment time-stamped 19:25:21, are you able to address this question:
Given the noise inherent in the temperature signal over the twentieth century after any long-term warming trend is removed, how rapid would a warming trend have to be in order for a statistically “significant” signal to be observed in less than a 15 year period?
Bernard J. (23:22:41) :
Im not sure what youre driving at.
If there is as much noise as you are talking about then how can warming or cooling ever be detected.
There is clear cooling in the temp record since 2005.
Do you see it?
BTW, you won’t see it in GIStemp.
Bernard J. (23:22:41) :
No statistically significant warming since 1995
http://wattsupwiththat.com/2009/12/26/no-statistically-significant-warming-since-1995-a-quick-mathematical-proof/
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which Phil Jones agrees with
http://wattsupwiththat.com/2010/02/14/daily-mail-the-jones-u-turn/
Amino Acids in Meteorites (21:08:17) :
That’s hilarious he actually does admit that there is no statistical significance in that warming
” it is difficult to establish the statistical significance of that warming”
while at the same time putting a it’s still warming significantly spin on it.
Amino Acids in Meteorites (20:45:03) :
“If there is as much noise as you are talking about then how can warming or cooling ever be detected.”
In the NH, we are going from winter to spring, and then to summer.
This is what we expect to observe, over the months.
But if you look at temperature data for the last week where ever you live, could you find a statistically significant warming?
carrot eater (12:53:33)
“…if you look at temperature data for the last week where ever you live, could you find a statistically significant warming?”
I see what you did there. We’re a week away from the vernal equinox. Ask that same question in the middle of June, or the middle of December in the S.H.
Right. By the time it’s June, it will have obviously have become warmer. But if you choose any one week between now and then, you will not see a statistically significant trend over that week. You’ll see some noise.
That’s the point.
AAiM (and Jan Pompe too, it seems).
Carrot eater has given you a clue.
It seems that my fairly obvious point sailed over your head, so all I can suggest is that you read my post again and parse it carefully – it poses a very important question that seems to be missed by most.
I really am interested in a serious response.
Those who are unable to address it are obviously not qualified or competent to comment on the nature of the warming trend since 1995, and those who are able to answer should be able to present a very important caveat to the commentary about the ‘significance’ of recent warming.
I’m surprised that this presents such a difficult hurdle for the apparently statistically literate people who comment here.
Bernard J. (01:21:44) :
I did understand your point. I don’t need to examine it more closely.
Should we start with the Medieval Warm Period instead of just the last 15 years or just the 20th Century? Maybe then we could see warming/cooling trend more accurately.
Jan Pompe (12:30:45) :
I agree with you.
At least the spot light he is now under since ClimateGate broke has this honesty, as much as it is, coming out of him.
Bernard J. (01:21:44) :
“I really am interested in a serious response.
I don’t think that you are. You seem to want to believe the spin that Jones tried to put on it.
If carrot-eater hasn’t overdosed on carrots then he really has no excuse for trying to draw an irrelevant comparison between a week and 15 years.
I suggest you get some real perspective:
http://wattsupwiththat.com/2009/12/09/hockey-stick-observed-in-noaa-ice-core-data/
and look at the trend and the variations over a few thousand years say to the holocene optimum. To get to this century just add .7C.
AAiM and Jan Pompe.
Neither of you have answered the question, even if you yourselves believe that you have.
I asked a simple question: paraphrased, it was – given the noise in the contemporary temperature time series, what minimum period of time is required to discern a signal from this noise? The answer requires some basic mathematical processing… beyond “just add .7C”.
I suspect that the calculations are beyond you, which is a pity because I really am interested in an informed ‘sceptical’ opinion on the matter.
Tamino had this to say on the subject:
http://tamino.wordpress.com/2009/12/15/how-long/
I really would like to know if anyone can counter his work, and claim that any period less than 15 years can actually give a meaningful indication of what the global climatic system is doing.
If not, the promotion of the “no (statistically significant) warming since 1995” meme is a demonstration of the scientific/statistical illiteracy/innumeracy of those who present it.
Bernard J. (15:51:56) :
You don;t get more basic than simple addition but if you don’t understand why I made that remark I don’t think I can help you.
Jan Pompe.
I know exactly why you made that remark.
And now I’m wondering if you can answer my question.
More specifically, I’m wondering if you can refute Tamino’s demonstration that anything less than 15 years provides the statistical power to rise above the inherent noise in the temperature signal.
I really am interested in your response to this. It will underscore the statistical validility that reinforces those who make the claim of “no warming since 1995” without further caveat, and in so doing it will indicate exactly those who are able to comprehend what is noise, and what is signal.
If anyone can show that it is scientifically/statistically possible to make a claim that it is possible to identify, with statistical significance, a warming trend (or, more significantly, a lack thereof) using less than 15 years of data, the world seriously needs to know about it. Such a proof would turn climatology upside down, and would be a boon in advancing the sceptic cause.
As AAiM has gone conspicuously quiet on this, could you do this Jan? Proof that less than 15 years of data are necessary to definitively identify a warming/cooling/static trend would go a long way to trashing Phil Jone’s apparent prevarication about the matter – and conversely an inability to provide such proof goes a long way to vindicating the intent of his statement, in addition to supporting Tamino’s work.
And for what it’s worth, I really don’t care two bits about Phil Jone’s “spin” or whatever: all I want to know is the scientific truth. Surely this is easy to provide?
If the basic addition of “.7C” is all that is required to blow that smug so-and-so Tamino out of the water, it shouldn’t take you too long to show why, Jan. If it takes a bit more than adding “.7C” to a quantity, then we need to know about this too.
This is the perfect opportunity for you, or AAiM, or anyone else with the statistical competence, to make a major point – so why can it not be made in a few quick sentences, or a few paragraphs at the most?
At it’s most basic the matter boils down to this:
1) there is undisputable noise in the temperature ‘system’
2) this noise necessarily means that there is a minimum period of data that must be gathered before a signal can emerge
3) there are statistical methods for determining what the length of such a period is, dependent upon the magnitide of the noise
4) if Tamino is wrong, it should be a simple matter to demonstrate why he is, and what the actual minimum period required to discern signal from noise is.
This should be bread-and-butter to those here who wish to demolish the claims of the AGW crowd. So where’s the answer?
AAiM (21:08:17, 11 Mar 2010).
I’ve been hoping that someone (and perhaps Luboš Motl himself) might follow up on your link to Motl’s post. Alas it seems that it’s not going to happen any time soon.
There are a number of (fatal) issues with Motl’s ‘analysis’, addressed in postings on that thread and also, by implication, in Tamino’s analysis. Whilst these flaws are interesting in and of themselves, insofar as they show what not to do, they (and Motl’s post) are actually not pertinent to the matter at hand.
Read my original post again. Motl’s naïve ‘analysis’ doesn’t actually answer my question.
Bernard J. (04:52:40):
There is no skeptic “cause”. There is scientific skepticism, and it must be kept in mind that skeptics have nothing to prove. Even so, here is a cooling trend of less than 15 years data: click
Tamino cherry-picks 15 years because it supports his CAGW agenda. But real world observations show that thirty years is about a half cycle of global /warming/cooling: click
Grant Foster has a personal agenda: catastrophic anthropogenic global warming; runaway global warming caused by human activity. Yet there is zero empirical evidence of that fantasy: click
As we see, for every one molecule of CO2 emitted by human activity, the planet emits 33 molecules of CO2 naturally. Those figures come from the IPCC.
Tamino is a thoroughly deranged True Believer, nipping at the heels of the Big Dog: WUWT. He is tortured by his irrelevance. If people accepted tamino as credible, they would have designated him as the “Best Science” site. Instead, he didn’t even make the finals.
Please, don’t waste any more of our time with the irrelevant tamino.
Bernard J. (04:52:40) :
“Jan Pompe.
I know exactly why you made that remark.”
No you don’t. You obviously have not understood anything
“And now I’m wondering if you can answer my question.”
I have no interest in doing that because I don’t disagree with what Tamino has done.
I DO NOT DISAGREE WITH THIS:
“The simple fact is that short time spans don’t give enough data to establish what the trend is, they just exhibit the behavior of the noise”
http://tamino.wordpress.com/2009/12/15/how-long/
But that and this from you
“More specifically, I’m wondering if you can refute Tamino’s demonstration that anything less than 15 years provides the statistical power to rise above the inherent noise in the temperature signal.”
Does not in any way say the same thing.
What I do disagree with (like AAIM) is that 15, or even 30 years or 100 maybe might be long enough. Especially in a system where we see lags of 800 years between temperature change and CO2 level Dansgaard cycles of ~1500 years during glacials and Bond events every 1000 -1500 years during interglacials.
Kapiche?