Why climatologists used the tree-ring data ‘trick’

http://scienceblogs.com/pharyngula/2009/12/why_climatologists_used_the_tr.php

by MikeCapone • 17 years ago

39 70 17 years ago

hga10• 17 years ago

Because otherwise people would have realized much earlier that their tree-ring data is not a useful proxy for temperature?

bjelkeman-again• 17 years ago

Do you have a good peer-reviewed article that shows that tree-ring data as a proxy for temperature is a poor fit. I'd be interested in reading it.

hga10• 17 years ago

a) One of the worst aspects of ClimateGate is how that group was keeping people less fervent than them out of the peer-reviewed literature.

b) All you have to do is look at how their tree-ring data (MXD to be precise) diverges from recorded temperatures starting in 1960, it declines, to be precise, to know why they felt they had to "hide the decline". Heck, look at the chart where they cut off the green line that represents this data just as it's starting to fall and conveniently where it's in a thicket of other lines so that you won't easily notice the cutoff.

robotrout4• 17 years ago

I don't have one. That's sort of the problem, though, isn't it?

With the climatologists interfering so strongly in the way this is supposed to work, by selecting which peers do their reviews, and by applying political pressure to the journals, the whole "look it up in the established body of work" approach has been sabotaged.

EDIT: I forgot an important one. The collusion aspect that the emails revealed. We're not going to put this result in our paper, even though we believe it, because it messes up Scientist B's premise.

thaumaturgy7• 17 years ago

You seem to be another carrier of the recent disease infecting HN, where users are commenting on articles that they didn't bother reading.

hga10• 17 years ago

Pray tell, how do you know I didn't read it? (In all fairness, I read some, skimmed the rest.)

nice1• 17 years ago

Another thing worth remembering in this context is that once people get used to lying with a straight face it is a hell of a job to stop.

MikeCapone• 17 years ago

Indeed. But at least that's more discouraged in scientific circles than in think tanks and PR/astroturfing campaigns financed by those who want to discredit science for financial gain.

cwan3• 17 years ago

And you don't think that the billions of dollars at stake in carbon trading don't result in proponents attempting to discredit critics?

cwan3• 17 years ago

This is how science is supposed to work. Sure there are a few straw men/ad hominem attacks peppered in the article but the proper response to criticism isn't calling the other side "denialists" and feigning offense but to respond with data and counter arguments.

The problem that many of these scientists have themselves compounded is the shroud of secrecy they've put over their "normalized" and "value added" data and methodologies. Painting Armageddon like scenarios and then obstructing freedom of information act requests when people ask about how they came about their conclusions is at best bizarre. Meanwhile we have a myriad of rationalizations from their defenders that we should instead trust their peer review which at the very least, the CRU/UEA emails show are suspect at least in this field.

Instead we are bombarded by these scientists/politicians who are anything but impartial who seem to present us with a binary choice that either we radically change our way of life which has serious risks in making us and the rest of the world significantly economically poorer or armageddon... and then they're surprised at the resistance? (This also ignores the myriad of policy responses like carbon trading being mired in corruption and leakages that are being advocated by these very same people)

It would seem to me that there are two parts to the problem - first understanding conclusively what has been happening and what will happen and second deciding what the appropriate policy response will be. Personally, I think AGW is likely but I also think that we are on the cusp of a massive transition towards clean burning (and more importantly, cheap) natural gas and alternative energies which makes at least the emissions as generated by much of the Western world moot.

jacoblyles2• 17 years ago

It still doesn't give a scientific reason why it is okay to truncate the tree ring temperature graph at 1960 and paste the real thermometer temperature graphs on top of them, except for the fact that it makes one hell of a picture. That's the "hiding the decline" that most people are concerned about. This article completely dances around that.

lionhearted• 17 years ago

I was going to comment that this borders on ad hominem:

> FoxNews.com tells us that we finally have a 'smoking gun'--proof that scientists are manufacturing a global warming crisis so that they can… they can…

You know, calling out political theater instead of acknowledging that reasonable people are concerned when they see scientific misconduct. I was going to explain that this sort of Fox News reference is not so good for the discussion - let the points stand, noting that one critic of yours is abrasive does not make the criticisms invalid.

But, then I came upon this a little lower, which is a bit less subtle about it:

> It's interesting stuff ... not interesting in the way that the rabid anti-science fuckhead (pardon me!) reality-denying luddite denialsphere types are saying, though.

Why might the science be wrong? Because it's moved from science to an identity issue. Us vs. them. This guy isn't helping.

rauljara• 17 years ago

Not to disagree with you that ad hominem attacks aren't helpful, but the article laid out a lot of interesting data based arguments which you yourself completely ignored. Intentionally or not, you instead preceded to cast "the science" into doubt in an ad hominem fashion. Ad hominem attacks are besides the point, and degrade conversion, but just because people use them doesn't make everything they say wrong.

thaumaturgy7• 17 years ago

This argument was framed in an "us vs. them" context a long time ago; that indeed has been one of the primary tactics and successes of the media engine of the right wing. It was obvious in Rush Limbaugh's earliest shows, and it's obvious in Fox News today.

I don't think it's altogether wrong for some people to be getting frustrated by this.

slyn• 17 years ago

"Why might the science be wrong? Because it's moved from science to an identity issue. Us vs. them. This guy isn't helping."

This is exactly why I choose to avoid the whole global warming climate debate thing. It is so hard to find any sort of unbiased information because everyone who talks about it has an agenda and forces it in your face. An Inconvenient Truth was actually gag worthy, an hour and fifteen minutes of Al Gore masturbating his ego over his crusade, five minutes of ridiculous cartoons, and maybe fifteen minutes of actual statistics. Obviously a station like Fox News or a talking head like Sean Hannity is going to push a right wing viewpoint to the death, so there is really no point bringing them up in any serious debate about basically anything. Even this posting, I just have a hard time taking this particular blog seriously given the "Evolution, development, and random biological ejaculations from a godless liberal", as the description, whether it is intended to be humorous or not.

The whole global warming debate is not as clear cut (if you can call it that) as something like stem cell research where the issue was basically science vs morality/religion. Both sides have their own statistics, both sides try their hardest to refute the other sides' science, and even the people who actually agree with each other that there is global warming often have different opinions on what can actually be done (if anything) to fix the problem. When something like the climate-gate situation becomes public, it makes it even harder to actually take any of the science seriously, because one can only assume that the studies, experiments, and modeling is being done with the intention of proving one side right or wrong, which will undoubtedly lead to all sorts of unintended cognitive bias.

thaumaturgy7• 17 years ago

If anything, I would expect the relatively recent divergence of correlation between tree-ring measurements and other climate measurements to bolster claims of an unstable climate, rather than suggest cooling.

Here we have a situation where plant behavior closely follows other measurements of the climate for a very long time, and then recently ... they don't. The most likely explanation here -- still being studied, mind you -- is that there has been a significant change in the interaction between trees and environment in certain areas.

robotrout4• 17 years ago

Which "other measurements of the climate" are you referring to exactly? CO2 level is not a measurement of climate, of course. It seems to be correlated, but it's unknown if its phase is leading or lagging. So, what measurements are you referring to?

thaumaturgy7• 17 years ago

> CO2 level is not a measurement of climate, of course.

LOL.

Well, that's it. I'm done. Have a nice weekend, folks.

InclinedPlane2• 17 years ago

More accurately, it draws into question the accuracy of tree-ring measurements as a proxy for temperature.

We do not have a situation "where plant behavior closely follows other measurements of the climate for a very long time". Instead we have a situation where one of the principle components of a small subset of tree-ring data generally follows other measurements of the climate for a very short time. And where even with all of that we still have "divergence" problems. These problems draw into question the validity of such measurements as a proxy for historical climate. If they do not track global temperature even a little accurately today how can we have any confidence that they do so in times long past when we don't have temperature records to check their accuracy?

The answer is that we don't. And every indication seems to be that many of these proxy reconstructions from the CRU are wholly inaccurate representations of historical climate.

yummyfajitas• 17 years ago

By your logic, any noise in measurement is evidence of instability in the system being measured.

Sorry, but that's nonsense. A simple thought experiment: use a blind man to visually measure the location of a rock. Does the fact that his answers are noisy provide evidence the rock is moving around in an unstable manner?

DanielBMarkham2• 17 years ago

I have spent some hundreds of hours listening to arguments for global warming, er Catastrophic Anthropogenic Climate Change or AGW or ACC (or whatever the PC acronym is this week)

The problem that I keep getting back to is best phrased like this: archaeological climate record extrapolation is nowhere near as sure-fire as supporters make it out to be. I have many more problems, but this one addresses the current article.

I understand these are honest, hard-working scientists, and they know a heckuva lot more than I do about their particular area, but as an intelligent person I can make fairly informed guesses based on the standards of proof required and the types of phrases being used. There a lot of "it appears" and "it seems" in there, phrases that mean that while consensus has been achieved (we'll take that as a given for this comment) it's nowhere near a slam-dunk. There's also quite a bit of ad-hominem character assassination going on, even in this piece. I find that folks who have to result to labeling and name-calling usually are insecure about their position.

Especially troubling is the way the current divergence is addressed. The argument looks to me like "we can use this data as a proxy for all periods except those where we have direct measurements to verify correlation" I find that weak at best.

To me, the layman, tree-ring data is going to show you how well a certain tree grew in a certain place over time. That might or might not have implications for the larger area or the entire planet. Like so many other pieces of this argument, it depends on having a control group and repeatable experiments -- none of which are doable. So it boils down to speculation. Speculation by great, intelligent people, perhaps, but speculation nonetheless.

I know some folks will say "no matter what the proof you're never going to believe" I don't know how to respond to that, except to point out that I've always been more interested in the character of the debate around GW and the political implications of letting scientific consensus drive public policy more than I have the actual facts on the ground. I have no more emotion invested in whether the planet is cooling or warming than I do variations of the gravitational constant around the time of the big bang. Whichever way the facts lead will not change my underlying concern. So I really don't have a dog in this fight as far as the science goes, at least not to the degree that some others do.

algorias• 17 years ago

This bothers me too. I don't know how tree-ring data is interpreted, but it's safe to assume that it's not a simple size of rings -> temperature mapping. How are the myriad of factors that contribute to tree growth accounted for?

InclinedPlane2• 17 years ago

How are the myriad of factors that contribute to tree growth accounted for?

The short answer is that they are not, because they are not known.

That's the point. If they were known there wouldn't be nearly so much controversy. Climate history modelling using tree-ring data as a proxy is incredibly immature. It may have value but the degree to which it has been relied upon is all out of proportion to the validity of the current state of the science (which is probably true for much of climate science at the moment as well).

lisper• 17 years ago

> Especially troubling is the way the current divergence is addressed. The argument looks to me like "we can use this data as a proxy for all periods except those where we have direct measurements to verify correlation" I find that weak at best.

Yes, I know that "+1" a weak comment. But I wanted to draw attention to this particular point because I think it's really crucial, and so far I have not seen it well addressed.

DanielBMarkham2• 17 years ago

I'll try to say it with some more detail.

Let's assume you have a sample from trees in one forest in say, Siberia, going back five thousand years. Do you know all of the environmental factors and how they've changed over that time period? Or do you just know how well the trees grew?

Assuming somehow you did know all of the environmental factors. Can you say with certainty how each of them affected ring width? Or are you relying on some sort of statistical correlation (which may be useful, but is NOT the same as causation)?

Let's assume that you know the micro-climate details and have established a very strong correlation between input factors and ring growth. With multiple or hundreds of factors I find that hard to swallow but let's say you did it. Now tell me, how many forests just like that do you need to sample to have some overall picture of global climate? Ten? A hundred? Does the data even exist in the numbers required? And how would you calculate the number required? It seems to me in order to be able to determine sample size you'd have to have a pretty good model of how the climate operated to begin with. And since this is the thing to be demonstrated, you can't also have this as a given -- that's circular logic.

As I understand the response to this, it relies heavily on statistical measurements and such. That's all fine and dandy, but it's a qualitatively different type of discussion than a theory-experiment-verify discussion. It's much more like a epidemiological study. And these are notorious for meaning much different things than researchers want them to. When all's said and done the only thing you may be proving is the statistical likelihood that certain trees will grow certain ways over the next few decades. Or you may have spent a lot of time proving or demonstrating nothing of any value at all, unfortunately.

logjam2• 17 years ago

>The problem is....archaelogical climage record extrapolation is nowhere as sure fire....

Then pray provide us with some science supporting your point.

If you cannot, when you just keep bleating you are "troubled" over and over, you really look like someone just pushing an agenda without any support whatsoever.

And oh, what's needed now is a "slam-dunk" on the issue. A "slam-dunk", of course, was never needed when any of the corporate interests (who are the ones really astroturfing and dissembling on this issue) set out to basically rape ecosystems for their stockholders. Do you also call for "slam-dunks" from these corporate interests, or just when it's convenient for your political ideology?

This whole discussion is reminiscent of the tobacco industries continual two-faced insistence on "slam-dunks" when it came to any encroachment on their ability to reap profit from suffering.

>I have no more emotion invested in whether the planet is cooling or warming than I do variations of the gravitational constant around the time of the big bang. Whichever way the facts lead will not change my underlying concern. So I really don't have a dog in this fight as far as the science goes, at least not to the degree that some others do.

Right. And in your disinterestedness you personally posted three anti-warming editorials to Hacker News over the last three weeks. Not three science articles - three editorials espousing a single view.

gloob2• 17 years ago

Paranoia and ad hominem don't do your argument much good.

waterlesscloud3• 17 years ago

I stopped reading at the word "bleating". Everything you wrote after that was wasted. Think about that before you post again.

skmurphy• 17 years ago

Assume that Daniel is rational. If you want to reach him how about focusing on actions that he might agree to? How about:

o increasing funding for monitoring temperatures on a worldwide basis so that we can get a better handle on where we are.

o increasing funding for monitoring CO2 levels (along with other greenhouse gases) to see if can get more data about the here and now.

Certainly we will need better monitoring of both temperature and CO2 gases to understand where we are and to monitor the effectiveness of any interventions that are agreed to.

It's often more effective to work from areas where you may agree and to tell if you are having a values conflict or a disagreement over facts and competing hypotheses for explaining them.

Another way to look at this would be to ask "what would prove to you the reality of both global warming and C02 as it's cause?" Or to answer "what would prove to me that global warming is not taking place is ________" and "what would prove to me that reducing C02 would not have an impact is _______ "

nfnaaron• 17 years ago

"There's also quite a bit of ad-hominem character assassination going on, even in this piece. I find that folks who have to result to labeling and name-calling usually are insecure about their position."

Yes, the amount of derision, even targeting scientists who merely hold an opposing interpretation of the data, is troubling.

gjm11• 17 years ago

Many biologists, palaeontologists, etc., apply "labeling and name-calling" to creationists; the person whose blog the original article here is posted on (not, as it happens, the author of the article itself) is a good example. I do not find it plausible that the reason for this is that those biologists are "insecure about their position".

So another explanation for the ad hominems remarked on here would seem to be: many climate scientists think that denying AGW is about as sensible as denying evolution. For what it's worth, this seems to me a more likely explanation than that they're "insecure about their position".

Incidentally, there's not exactly been a shortage of ad hominem attacks going the other way. My impression, of which I'm not particularly confident, is that the density of personal attacks on opponents is higher in the output of AGW disbelievers than in that of AGW believers.

thwarted• 17 years ago

I know some folks will say "no matter what the proof you're never going to believe"

If there was proof, you wouldn't need to believe. Anyone who says "you're never going to believe" isn't looking to convince anyone, they're looking for others to have blind faith in order to have their own faith validated.

fauigerzigerk• 17 years ago

It's interesting and important to read the comments below that article. What this shows is that seeing a smoking gun in the "nature trick" email alone is misplaced, but also that the interpretation of what's going on with those tree rings is not nearly as clear or uncontroversial as the global warming alarmists want us to believe.

w00pla• 17 years ago

Is anyone a little disturbed about that website? From the title "Evolution, development, and random biological ejaculations from a godless liberal".

On the sidebar: "The Rise of Atheism, Global Atheist Convention".

This guy is some type of Atheist cult member.

albemuth• 17 years ago

> "Atheist cult" That's quite an oxymoron don't you think?

btilly• 17 years ago

Not at all. Atheism is without God or gods. This is not the same as without religion.

As an example some Buddhist sects are both atheistic and cults.

jellicle• 17 years ago

Watching Hacker News argue about climate change is like watching the blind argue about colors. Please stop. In general you have no idea what you are talking about.

Again and again and again and again there are comments along the lines of, "I did five minutes of Googling about this issue and I've come up with a fatal flaw in climate science!" Do you really think that the tens of thousands of scientists who do their life's work in this area are all fucking idiots? Every last one of them? You are late to the party. How greenhouse gases work has been thoroughly explored. The science of whether we'll get a substantial human-caused climate change from increasing the amount of atmospheric CO2 by 35% is done. It's over. The science now is in determining/predicting just how much it will be, and in predicting the effects.

Every thread about climate science on Hacker News is one giant facepalm. Every thread. Please stop.

pg• 17 years ago

Your comment has even less evidence or analysis than the comments you're complaining about. It's just an angry assertion.

It's ok for people to who are not experts in a subject to explore it. If you feel they're on the wrong track, help them by giving them information.

antonovka2• 17 years ago

There's an over-abundance of information. All that's left for HN is angry, emotional quibbling by those who lack the basic qualifications to evaluate the data and science, even if they were interested in actually doing so.

waterlesscloud3• 17 years ago

Are there really 10s of thousands of scientists doing climate work? What is your source for that? It seems like a high number.

waterlesscloud3• 17 years ago

Answering my own question, there may in fact be 10s of thousands of "climate scientists", for a very broad definition of climate scientist.

http://rabett.blogspot.com/2006/11/how-many-climate-scientis...

Interesting to note though, how low the number is for scientists actually working on climate change.

CamperBob• 17 years ago

FTA: The main cause seems to be increasing atmospheric carbon dioxide.

Call me when you're sure. Extraordinary calls to action require extraordinary proof.

brc• 17 years ago

I've read through the article, and what it all says to me is that there are more questions on answers, and a lot of speculation as to the divergence problem. While there are some sound suggestions as to why, it would seem to me that these are all enough to discount tree rings as a useful proxy until they are better understood. To me, the use of statistical methods to blend out the divergence from a specific date seems like a real fudge.

sown• 17 years ago

I love HN. Everyone here is an expert on anything.

vikram• 17 years ago

Does one need to be an expert to follow the argument and form an opinion about it? If that was the case then why don't we let the experts make decisions, not just provide information.

rms2• 17 years ago

If AGW is a vast scientific left-wing conspiracy, I think it's diabolically brilliant. Surely everyone thinks reducing pollution and fossil fuel dependency is important, right?

hga10• 17 years ago

How important? Look at the arguments of Bjørn Lomborg, "The Skeptical Environmentalist". He says e.g. there are far better ways to spend the world's money to improve lives than e.g. what's being proposed WRT to AGW/CC.

rms2• 17 years ago

http://news.ycombinator.com/item?id=1005924

Why climatologists used the tree-ring data ‘trick’

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