Bishop Hill Reisinger and the divergence problem
Feb 22, 2010 Climate: CRU Climate: MWP Climate: other An interesting article from the New Zealand Herald, looking at the divergence problem. What particularly fascinated me was the explanation of the issue from Andy Reisinger, who some will remember as being a man who is very close to Rajendra Pachauri.
Reisinger is a climatologist, but not, if I remember correctly, a paleo guy. It's odd then to see him being the expert interviewed on the subject of the divergence problem. It might also explain the explanation he gives for this inconvenient effect:
Dr Andy Reisinger, a climate researcher at Victoria University who has followed the progress of proxy temperature reconstructions, said it could be that a lack of rain in recent decades had stunted tree growth in some high-altitude spots - or that when temperatures reached a certain point, trees began to react differently.
Whatever the cause, "the relationships [between tree-rings and temperature] that we've developed for the last 500-100 years may not apply in the last 50," he said.
Now correct me if I'm wrong, but I thought that paleoclimatologists picked trees that were sensitive to temperature rather than precipitation when they set about recreating temperatures of the past. If a drop in rainfall can cause a drop in growth now, then it could have caused a drop in the past. In other words, the paleo guys will have to admit that they know absolutely nothing about temperatures before the nineteenth century.
Reader Comments (79)
Sounds like a pretty fair assessment to me, yer Grace, but I'm sure Frank O'Dwyer will be along shortly to set you straight on the matter.
Spot on. I assume that Briffa et all tried to evade answering this question and would be forced to give this kind of explanation, understanding that every reasonable thinking person would raise the obvious question you did. I could imagaine that Briffa and others will not be happy with this article from Reisinger.
"the relationships [between tree-rings and temperature] that we've developed for the last 500-100 years may not apply in the last 50"
Aha! Trees started behaving differently 50 years ago. Damned sneaky things, trees.
I live in New Zealand. I would be happy to engage Dr Reisinger in a public debate with BH and McIntyre et al.,
This issue seems fairly crucial.
If I can help, let me know.
Tree rings do not represent modern day temperatures, for that you have to hide the decline. But for the last 1000 to 2000 years they are the gospel truth, specially when they so neatly do away with the medieval warm period and little ice age.
This does seem a rather telling claim. But surely (and I offer a Borders chocolate hobnob in mitigation against this being a stupid question) when calibrating and verifying your model of tree rings vs temperatures you would do this against each type of tree and in different locations ?
And in any case aren't there controlled environments around - greenhouses, Eden centre for example.
In other news I'm still waiting for a BBC reporter to be picture pointing at a level below a see wall with the lines "sea level rises may be much lower".
http://wattsupwiththat.com/2010/02/21/2009-paper-confirming-ipcc-sea-level-conclusions-withdrawn-mistakes-cited/#more-16611
I won't hold my breath though.
Let us pretend we inhabit an alternate Universe and a Professor sent out his research students to go out and find good ways of determining past temperatures from nature.
One student comes back and says: " this SEEMS to work well, except PERHAPS for the last 50 years".
Professor: "This method cannot predict the last 50, but claims it can predict the last 500? Go away and do not waste my time."
Why does consensus "climate science" need an alternative universe to make sense?
"In other words, the paleo guys will have to admit that they know absolutely nothing about temperatures before the nineteenth century."
I think you meant "ought to" rather than "will have to". There seems to be a determined circling of wagons around fixed positions at the moment, with the enthusiastic connivence of the scientific press.
PS - here is another gem from the NZ Herald:
"I am indebted to a reader for sending me a copy of an article which appeared in this newspaper and which I hadn't read.
Under the headlines "Man is making the earth too warm, Threat of melting polar caps", it quoted a prominent physicist as saying that the levels of the oceans could rise 12m and flood vast areas of the Earth in the next half century unless atmospheric temperatures were controlled.
The physicist, Dr Joseph Kaplan, professor of physics at the University of California, said such flooding could occur as a result of accelerated melting of the polar ice caps.
..Now the reason I missed that story is that it appeared in this newspaper on Tuesday, April 9, 1957, at which time I was 16 years old and preparing to travel by ship to the United States on an American Field Service scholarship."
Climate hysteria won't last test of time
http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=10626802
"Whatever the cause, "the relationships [between tree-rings and temperature] that we've developed for the last 500-100 years may not apply in the last 50"
You can only establish a relationship if you know both variables, for points outside your database it is an extrapolation of the relationship. So is he claiming a reliable temperature record going back 500 years?
One thing I've often wondered since this whole bouhaha started vis-a-vis the divergence problem, is how do we know the temperature measurements are the correct ones, given the doubts over adjustments to raw data? Maybe the trees are telling the truth?
Yes, DocBud has hit the logical nail on the head. If you have a period of recorded temps, say 100 or 200 years long, and for 50 of those years your supposed temp proxy does not correlate with the actual recorded temps, you have a bad proxy. It is that simple. You cannot extend back because you have no proper temperature record going back far enough to justify against.
So yes, you do have to admit that tree rings are not robust temperature proxies for the last couple thousand years, and that this is what the divergence of the last 50 years shows.
It is also logically correct that if the indicator is in fact a reliable proxy, then the temperature record of the last 50 years is mistaken. But you can't have it both ways, you cannot simultaneously claim a robust temperature record over the whole period and also that tree rings are robust temperature proxies.
Its all coming apart.
Quite. Not that any mainstream politicians will take notice. We truly inhabit a parallel universe.
One of the central principals in Geology is Lyell's "Uniformitarian" view, that "The present is the key to the past"
Simply put, we can see virtually* all processes that have operated in the past (back to about 2.5 GA) operating today, although obviously, high intensity events, which leave a large physical record, only occur very infrequently.
I quite like the idea that the high latitude and high altitude trees might be telling the truth (if we looked at decent size samples of them, rather than a dozen or so cherry picked individuals), but it really isn't my field to give considered comment on. I'm an engineering and minerals geologist.
*an exception to this is deposition of oolitic ironstone. I don't know of any present day example.
"In other words, the paleo guys will have to admit that they know absolutely nothing about temperatures before the nineteenth century."
Shouldn't that be "dendro guys" rather than "paleo guys"? Ice-core temperature reconstructions seem to stand up quite well compared to other data (like glaciations).
In engineering, a correlation (between tree rings and temperature in this case) would not be used outside its range of validation.
Could it be that "when temperatures reached a certain point, trees began to react differently" during the MWP, too? :-)
I think the brown stuff is about to hit the whirly thing in Climatology.
This, to me, is another example of people slowly modifying their positions to gain best advantage for when the landslide begins to gather pace.
He's looking to stand on some bedrock.
I think you guys are out of your depth. Briffa et al are the world experts on the divergence problem.
Sounds a bit like he wants to say "Trees make very bad thermometers" - but can't quite bring himself to, as that would make him a 'denier' :0 ...
@Anon
"You are out of your depth" comment should actually be directed to Dr. Reisinger. However, the good Doctor only complimented the problems that many see with Dendro Science.
Those you mentioned should be world experts on the problem, they created it ;)
During the hot summer of 1976, I was pushing pens for the Forestry Commission. The guys who actually grew the trees were positive that the heat, sans rain, would be bad for growth.
Perfectly logical. When the AGW hypothesis finally penetrated my interest, and I learned that trees were being used as proxies for temperature, with no consideration of precipitation, I smelled a rat.
Oo you callin' a rat, Mr Jeff bloody Wood? My Phil's a good boy, 'e is. Shut yer face.
An amusing new short film from OwlGore:
http://www.xtranormal.com/watch/6133365/
In normal mathematics and physics at least, divergence always leads to greater levels of measurable inaccuracy, and logical inconsistencies. And when the predictions of theory diverge from observation, it's the signal that a new theory is required.
To paraphrase Einstein, no experiment can ever prove a theory, no matter how many are consistent with it, but only a single observation inconsistent with the theory is required to refute it.
But we are not dealing with normal science here, but "post normal", as advocated by UEA's Mike Hulme, where it's no longer necessary that the observations have to fit the theory.
Trees are not thermometers and neither are glaciers.
I am sorry to have upset Prof Jones' Mum, but My Dear, he has been a very naughty boy. You should have beaten him more when he was a lad.
The more I see and study about dendro, the more I'm tending toward using part of my vast fortune to endow a Chair at UEA, a Professorship of "Climatic Re-creation from Examining the Entrails of Goats" seems quite apposite.
But they have a perfect answer to this divergence problem. The reason that tree rings don't fit with late 20th century temperatures is because the trees have been adversely affected by .... man-made global warming!!
It seems to me that "adjustments" made to the actual recorded temperatures in the last 50 years may explain the tree ring divergence problem. Either that or the trees have developed a sense of humor for us skeptics to admire.
Pogo, would not Entrails of Pigs be more appropriate for the acronym?
On the one hand we are told to bow to the greater knowledge of the science that is the lifeblood of the climate science community, while on the other we have a climate scientist telling us that the last 50 years of tree rings have been upset by precipitation so can't be used, while the previous thousand years can. Does he have the precipitation for the previous thousand years in sufficient detail to say that?
It's junk science and the scientists coming out with the sort of stuff you'd get your arse kicked for not understanding for O Level physics should hang their heads in shame.
Richard - what a cracking article from the NZ Herald..!
Can't wait to feed that in at an appropriate juncture in the climate 'discussion'....
El Reg strikes again
Global warming worst case = Only slight misery increase
http://www.theregister.co.uk/2010/02/22/stanford_warming_n_poverty_study/
Seems even if temps increased by a wopping 1.5 C not so much misery results for the worlds poor..so says.a Stanford Uni study
http://news.stanford.edu/news/2010/february15/lobell-aaas-climate-022010.html
There are a number of statements out in the literature about how there has been an increase in precipitation because of global warming - so I went and had a look at the data -
http://bittooth.blogspot.com/2010/02/precipitation-hypothesis-is-it-true.html
And it doesn't appear to be true, either for my own state of Missouri, or for the globe.
Richard:
"But for the last 1000 to 2000 years they are the gospel truth, specially when they so neatly do away with the medieval warm period and little ice age."
Actually, as I am am sure you are aware, they don't. Not unless you cook the books with unfit proxies, hide the fit ones, ignore the principles of statistics and mathematics.
Note tho' does not include the impact on food markets of creating biofuels from US corn....
"In other words, the paleo guys will have to admit that they know absolutely nothing about temperatures before the nineteenth century."
The point has been made that this is just in relation to dendro, not the whole of paleoclimatology. But even so, is it too strong? "Absolutely nothing" is a very strong claim. I'm no expert, so tell me if I'm wrong, but there does seem to be some correlation between growth rings and temperature. The wikipedia page says
'Samples from southern forests do not exhibit this divergence, though this could be due to paucity of samples, and not all trees in the northern hemisphere do. Divergence is most common in the far northern hemisphere.'
(Yes, I'm quoting wikipedia: as I say, I'm no expert.) I do think the divergence problem is important, but think I would need more evidence before concluding that trees can tell us "absolutely nothing" about past temperatures.
JK
Possibly, but it is likely that the correlation there is is a function of cherrypicking. Nobody has yet done the study where they take all northern treeline/upper treeline series and see if they correlate to temperature. At the moment they pick the ones that correlate and say that these are the ones that are responding to temperature.
The "divergence problem" logically invalidates the use of dendro as a basis for past temp reconstruction. If tree rings are not valid for determination of present conditions, then there is no logical reason to believe that they've been valid in the past.
IIRC, Mann and Co were warned prior to the invention of the hockey stick that the data was not valid for temp reconstruction. They used it because it was convenient and supposedly confirmed their prejudices.
Reisinger should perhaps read the Climategate emails, and dendro Ed Cook would tell him how much the dendros don't know about temperature more than 100 years ago:
“…but honestly know fuck-all about what the >100 year variability was like with any certainty (i.e. we know with certainty that we know fuck-all).”
- Ed Cook, from email 1062592331.txt.
Context is here: http://co2realist.com/2009/11/29/email-ed-cook-and-keith-briffa/
Reisinger should perhaps read the Climategate emails, and dendro Ed Cook would tell him how much the dendros don't know about temperature more than 100 years ago:
“…but honestly know fuck-all about what the >100 year variability was like with any certainty (i.e. we know with certainty that we know fuck-all).”
- Ed Cook, from email 1062592331.txt.
Context is here: http://co2realist.com/2009/11/29/email-ed-cook-and-keith-briffa/
@The Bish: "At the moment they pick the ones that correlate and say that these are the ones that are responding to temperature."
Isn't that known as "The Texas Sharpshooter" effect?
Excuse me if I'm out of line, here.. but did any of these climatists consult an arborist?
I'm just a poor dumb systems engineer and have nothing to go on but observation. My understanding is that tree growth varies based on temp AND water available.
The fall leaf turning brilliance depends largely on precip and temp. IE the colors are more brilliant when the season has been dry and there's a larger representation of the environmental trace minerals in the sap.
-so-
It seems to me that some of that water was absorbed in trunk growth so there should be a way to test for temp v precip using mass spectroscopy:
The higher the content of trace mineral per ring, the dryer the environment for that season.
Then again, I'm just a poor dum punter.
What incredibly ignorant hand waving. Both of his explanations for the divergence are things that could have caused divergence in the past. So after doing that he leaps to the irrational and completely unsupported conclusion that it's only happened in the last 50 years.
To quote the late John L Daly:
My emphasis. It amazes me that these people get funding for obvious nonsense.
People who write forestry management software will attest that even when you know all of those variables for a given tree for a given year, it's very, very difficult to predict the ring growth for the year.
Tree rings will tell you a lot about what happened to the actual tree that the rings are taken from. But you will get variability from tree to tree for the same type of tree when they are just yards apart. It is this very variability that provides fertile ground for cherry picking from when you want to throw selected data at a hockey-stick generating algorithm.
Over the last three months since Climategate, not one of Climate Cultists' inner circle --the Green Gang of Briffa, Hansen, Jones, Mann, Trenberth et al.-- has published any article of substance relating to Warmists' previously indubitable AGW hypothesis. The gist is always, "Prevention is the only cure", "Who are you to criticize puissant Ascended Masters in this field?", "Who cares about trendlines-- it's warming, warming we tell you! You want facts, the fact is we have too much at stake here to admit anything, no matter what exposed stupidities we retract."
Science from Copernicus to Galileo to Darwin and 20th Century quantum theorists has witnessed many contretemps, but recusant Warmists take the cake. Will James' description of the Anabaptists of Munster comes to mind (see "Varieties of Religious Experience", 1902). Warmists in brief exhibit truly pathological behavior, due for a come-uppance that will forever render their flailing idiocies a laughing-stock. Can't happen soon enough.
Phillip Bratby said, "In engineering, a correlation (between tree rings and temperature in this case) would not be used outside its range of validation."
When I describe the "divergence problem" to my engineer colleagues, their first reaction is to think I'm either mistaken or joking - they can't believe that such a basic principle has been ignored to that extent, in something that has had such an impact on "climate science". I think a large reason why not more people are aware of the issues is because they can't believe such a high-profile science could be *that* flawed.
"or that when temperatures reached a certain point, trees began to react differently."
Why wouldn't that apply to the reconstruction years as well? Here we see the active avoidance of huge and obvious uncertainty in the data. You have a wide error window and they cherry-picked their assumptions for a preferred extreme case that not surprisingly fits in the huge window and backs them up. The assumption
David Chappell, Entrails of Pigs=PoE's? Hebrew acronym humor? Would you be clear please?
David Chappell, here is another one. New World Order becomes NWO, in Hebrew=OWN:)