Why climatologists used the tree-ring data ‘trick’ • Hacker News Board

Re: Why climatologists used the tree-ring data ‘trick’

#21

Post by robotrout » Sat, Dec 19, 2009, 7:26 PM UTC

thaumaturgy wrote: post #12

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, mi…

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?

Re: Why climatologists used the tree-ring data ‘trick’

#22

Post by InclinedPlane » Sat, Dec 19, 2009, 7:26 PM UTC

thaumaturgy wrote: post #12

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, mi…

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.

Re: Why climatologists used the tree-ring data ‘trick’

#23

Post by hga » Sat, Dec 19, 2009, 7:28 PM UTC

cwan wrote: post #16

thaumaturgy wrote: post #9

Earlier quoted context omitted.

The current views in climatology were developed long before there were "billions at stake". Meanwhile, if there are "billions at stake" in the "green" industry, there are trillions at stake in those industries that would like to not have to install complicated and expensive filters for their manufacturing exhaust, and for the automotive industry which would surely love not to have to meet quite so stringent air quali…

Sure (though the millions at stake in academic research particularly given the political climate as the leaked emails illustrate are also of significance) - but let's first separate the conversation to understanding that (1) what's the problem and (2) what we should do about it are two separate issues. Let's also understand that much of the western world like the US are about to show significant declines in carbon em…

By my count of an enumeration in The Wall Street Journal (in an OPED) there's currently well over 5 billion in academic "research" at stake annually. Paul Jones, the top dog in the CRUtape Letters, himself pulled in 22 million in the period in question.

Re: Why climatologists used the tree-ring data ‘trick’

#24

Post by thaumaturgy » Sat, Dec 19, 2009, 7:30 PM UTC

robotrout wrote: post #17

bjelkeman-again wrote: post #4

Earlier quoted context omitted.

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.

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 go…

You're kidding, right?

Evidence of absence is not proof. Imagine if this argument were used in other contexts: "there are no papers published in peer-reviewed journals about intelligent design. This proves that there's a conspiracy in the biological community!"

In fact: there are a few published papers which challenge popular climatological measurements and papers, and they are cited as often as possible by ... I don't want to call them denialists, but I'm not sure what else to call them.

So, wrong on both counts.

Re: Why climatologists used the tree-ring data ‘trick’

#25

Post by hga » Sat, Dec 19, 2009, 7:31 PM UTC

thaumaturgy wrote: post #18

hga wrote: post #13

Earlier quoted context omitted.

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

Thanks (sincerely) for being honest about that, at least. There were two clues: one, your comment timestamp was not far removed from the time that the article was posted. I read pretty quickly, but it still took me some time to fully read and digest the entire article. Second, there was your statement: "their tree-ring data is not a useful proxy for temperature". The article specifically mentioned that tree-ring data…

No, it doesn't answer why they felt they had to "hide the decline" instead of discussing and justifying how the recent divergence is congruent with their claims of its usefulness as a proxy when there were no (accurate) temperature readings. These are not the actions of honest men.

Re: Why climatologists used the tree-ring data ‘trick’

#26

Post by algorias » Sat, Dec 19, 2009, 7:33 PM UTC

DanielBMarkham wrote: post #20

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 artic…

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?

Re: Why climatologists used the tree-ring data ‘trick’

#27

Post by lisper » Sat, Dec 19, 2009, 7:34 PM UTC

DanielBMarkham wrote: post #20

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 artic…

> 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.

+1

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.

Re: Why climatologists used the tree-ring data ‘trick’

#28

Post by thaumaturgy » Sat, Dec 19, 2009, 7:36 PM UTC

robotrout wrote: post #21

thaumaturgy wrote: post #12

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, mi…

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?

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

LOL.

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

Re: Why climatologists used the tree-ring data ‘trick’

#29

Post by robotrout » Sat, Dec 19, 2009, 7:39 PM UTC

thaumaturgy wrote: post #24

robotrout wrote: post #17

Earlier quoted context omitted.

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 go…

You're kidding, right? Evidence of absence is not proof. Imagine if this argument were used in other contexts: "there are no papers published in peer-reviewed journals about intelligent design. This proves that there's a conspiracy in the biological community!" In fact: there are a few published papers which challenge popular climatological measurements and papers, and they are cited as often as possible by ... I don…

Reread my post. I didn't say that the absence of papers proved anything. I said that the scientific process has been sabotaged in this instance, making things more unclear than they should be.

You are slick though!

EDIT: Perhaps you're honestly confused. I'm a bit doubtful on that, but in case you are. We know that the process has been sabotaged. Not because there are no papers, but because many of the details of the sabotage were revealed in the ClimateGate emails.

Re: Why climatologists used the tree-ring data ‘trick’

#30

Post by DanielBMarkham » Sat, Dec 19, 2009, 7:44 PM UTC

lisper wrote: post #27

DanielBMarkham wrote: post #20

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 artic…

> 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. +1 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 addre…

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.