Internal dissent: "Personally, I think that the tree ring records should be able to reproduce the instrumental record"

Severinghaus and “Hide the Decline”

By Steve McIntyre

One of the very first contributions to realclimate was an FAQ from Jeff Severighaus on Dec 3, 2004. A year earlier, Severinghaus attempted (unsuccessfully) to get an explanation of the “divergence” problem from Mann and the rest of the Team. Severinghaus had become interested in the question following a presentation by Tom Karl of NOAA in which he had used a figure from Briffa and Osborn 2002, in which he wondered about the “flat” response of the tree ring proxies in the last half of the 20th century.

In nearly all defences of the deletion of the decline in spaghetti graphs that yield a rhetorical effect of coherence between the Briffa and other reconstructions in the last half of the 20th century, it’s been argued that the divergence problem was fully disclosed in a couple of 1998 Briffa articles and that this disclosure in the original technical literature constituted sufficient disclosure – a point that I contested long before Climategate.

The Severinghaus exchange is highly pertinent to this issue. Severinghaus was a climate scientist who was not a specialist in the area who asked specifically about a diagram in which the decline had been hidden (though Severinghaus was unaware that the decline had been hidden.)

Severinghaus was concerned merely by the flattening of proxy response. One can only imagine how the exchange would have read had Severinghaus been aware that the Briffa reconstruction actually declined sharply. Read and see whether Mann, Jones and/or Briffa drew Severinghaus’ attention to the early articles in which the divergence problem was disclose.


On the afternoon of Feb 1, 2003 California time (emails -2545, 19, 4355 Feb 2, 2003 00:15 GMT), Severinghaus wrote to Tom Karl of NOAA about his presentation at the MIT Global Change Forum the previous day. Severinghaus asked about the “flat” response of tree rings to late 20th century warmth, referring to an article by Briffa and Osborn in Science (2002). The diagram in question would be the following:

Figure 1. Briffa and Osborn (Science 2002) Figure 1.

Severinghaus observed that this lack of response is an “embarrassment” and that it “casts doubt on the integrity of the proxy”:

Subject: tree rings and late 20th century warming

Date: Sun, 2 Feb 2003 16:15:04 -0800

From: Jeff Severinghaus

to: Thomas.R.Karl

Dear Dr. Karl,

I enjoyed your presentation yesterday at the MIT Global Change forum. You may recall that I asked about the failure of tree rings to record the 20th century warming. Now that I look at my records, I realize that I remembered this wrongly: it is the LATE 20th century warming that the tree rings fail to record, and indeed, they do record the early 20th century warming.

If you look at the figure in the attached article in Science by Briffa and Osborn, you will note that tree-ring temperature reconstructions are flat from 1950 onward. I asked Mike Mann about this discrepancy at a meeting recently, and he said he didn’t have an explanation. It sounded like it is an embarrassment to the tree ring community that their indicator does not seem to be responding to the pronounced warming of the past 50 years. Ed Cook of the Lamont Tree-Ring Lab tells me that there is some speculation that stratospheric ozone depletion may have affected the trees, in which case the pre-1950 record is OK. But alternatively, he says it is possible that the trees have exceeded the linear part of their temperature-sensitive range, and they no longer are stimulated by temperature. In this case there is trouble for the paleo record. Kieth Briffa first documented this late 20th century loss of response.

Personally, I think that the tree ring records should be able to reproduce the instrumental record, as a first test of the validity of this proxy. To me it casts doubt on the integrity of this proxy that it fails this test.



Severinghaus obviously didn’t know that the Briffa and Osborn diagram had deleted the post-1960 decline from the Briffa reconstruction. Had they shown the actual data, the diagram would have looked more like the one shown below.

Read the full post at Climate Audit

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November 28, 2011 9:50 am

OT: I just want to give a shout out to “Ray Ladbury” for helping to make me an AGW skeptic over the years I have been lurking at RC and WUWT. You’re doing a heck of a job, “punkin.”
The difference in tone between the two sites is so striking.
(Who is that guy anyway? Please tell me he’s not a scientist.)

November 28, 2011 10:02 am

If it doesn’t follow the measured temperature record it isn’t a proxy for temperature, end of story.

doug s
November 28, 2011 10:16 am

“But alternatively, he says it is possible that the trees have exceeded the linear part of their temperature-sensitive range, and they no longer are stimulated by temperature.”
Oh yes, this certainly is a reasonable theory…
how about…
“But alternatively, he says it is possible that CO2 has exceeded the linear part of its sensitive range, and CO2 no longer are stimulates temperature.”
Oh no, that is absolutely preposterous, it increases exponentially!!!
Uh huh…

November 28, 2011 10:30 am

Tree rings are proxies for aggregate growth conditions, one of the items in that aggregate being temperature (and generally only temperature in a specific portion of the year, colder winter temperatures, for example, will generally not show up in tree rings). For example, we are now looking at the possibility that increased snow pack in the winter resulting in later melt off (delayed warming of the soil) possibly has a significant impact on tree ring growth so if you have a period of increased winter precipitation you might have reduced growth rates the summer air temperatures notwithstanding. CO2 itself can cause increased growth rates, too. Changes in the pH of the rain could impact the absorption of nutrients. Changes in cloud cover, changes in animal migration routes (nitrate availability from animal droppings), fires (small forest floor fires releasing nutrients) can play a role, etc. And the problem becomes even worse when a tree ring series is winnowed down to only a few trees and only these few used in the reconstruction. Were those the trees that a reindeer crapped next to? Did a neighboring tree in the immediate proximity of your selected tree die and fall over or lose a limb in a storm and allow more sunlight to reach the selected tree? It seems to me that the whole thing is smoke and mirrors if you are selecting only certain trees from a series to meet your criteria for inclusion in a representative sample as a temperature proxy. I want to know what the overall response has been for all of the trees sampled. I would expect that to filter out the noise from a tree falling over. I just don’t have a lot of faith in time series where the members are picked for response to “temperature” when that “temperature” record itself is possibly tainted.
Oh, hey, by the way, I was driving through the Inyo National Forest this summer South and East of Mono Lake on Highway 120 and apparently there was a fairly recent fire there. There are several rather large trees down and several of them cut into “chunks” and they might be good for collecting some ring samples.

Brandon Caswell
November 28, 2011 10:35 am

Trees are a good indicator of temps, except when they are not, but they know when this happens and will fix everything for us laymen. Good thing we have climate scientists to point out when black is white for us.

Nick Shaw
November 28, 2011 10:37 am

I am always amazed when ostensibly intelligent people never say, “That doesn’t answer my question! In fact, you appear to feeding me crap!”
Why is that?

November 28, 2011 10:43 am

based on my understanding of tree rings as proxies for temperature the only way to use a tree ring size for a temperature is to calibrate tree rings against known local temperatures which would give you a rough conversion i.e. tree ring of x size = y temperature … this conversion value is arrived at by matching tree rings against know temperatures. In this case tree rings for the past 100 ish years are compared against local temperatures for the same time period and thus a conversion factor is calculated. In that case it should be impossible for tree rings to widely diverge from temperatures since the temperature gives us the proxy value of the tree ring. In fact the one period of time when tree ring “temperatures” simply should not diverge greatly from local measured temperatures is during these calibration years.
This all assumes that tree rings are in fact actual proxies for temperatures.
I suspect they ignored recent tree ring calibration values because when they included them all of their older tree ring proxies showed much higher temperatures and would have destroyed their meme of AGW and also would have shown tree rings to be useless proxies for temperature …

Brandon Caswell
November 28, 2011 10:43 am

“he says it is possible that the trees have exceeded the linear part of their temperature-sensitive range, and they no longer are stimulated by temperature”,…………. but they are positive that this has only happened in recent times and never before in the past…….because our tree rings don’t show any warming in the past comparable to today………..
I learned at a young age it was impossible to lift a board off the ground while I was standing on it, but that kind of circular reasoning is the thing a great climate scientist is made of.

November 28, 2011 10:44 am

If just one tree that Briffa used – YAD061 – had been left out, the entire hockey stick shape would have been eliminated. Either Briffa knew that, or he is too ignorant to be employed in anything above manual labor.
I think he knew exactly what he was doing: cherry-picking proxies to create an alarming hockey stick shape, in order to generate grants. IMHO he is no different than the rest of the climate charlatans who suck up federal grant money based on this kind of deception.

November 28, 2011 10:45 am

Uhhgg!! The graphic is too large! The end, (the place pertinent to the post) is obscured by the WUWT facebook advert.

November 28, 2011 10:48 am

I should know this, but where is Severinghaus now? He must know about hide the decline, what does he say now?

November 28, 2011 10:52 am

A comment on Peilke the Elder’s posting (since his comments are turned off), I happened to notice this from Adrian Simmons.

I’ve now computed a set of monthly means of daily max and min temperatures from ERA-40. They are not based directly on any observations of Tmax and Tmin. Instead they are derived from maximum and minimum values computed during each of the six-hour background forecasts of the data assimilation system.
The first attachment shows trends in the daily temperature range for the periods 1958-2001 and 1979-2001. This shows a reduction over time for North America (1958-2001 at least) and for eastern Europe and much of Asia. Values in the tropics must be treated with most caution as we know we have spurious trends in some aspects of the hydrological cycle which could well impact the daily temperature range. The trend over the US may be biased a bit by a too-dry troposphere from 58-63 caused by wrongly encoded humidity observations in one of the radiosonde datasets supplied to us – we picked this up too late to allow correction in ERA-40 production.
The other plots show the trends in maximum and minimum temperatures for 1958-2001 and 1979-2001. Overall the short-range forecast trends are quite consistent with the trends for the daily mean analyses (Fig 7 in the document attached to yesterday’s mail). The increase in daily temperature range over northern latitudes is seen to be associated with a larger rate of increase of minimum than maxiumum temperatures – at least we seem to have got the most basic feature right.
The Tmax and Tmin trends for 1958 to 2001 also show that the almost certainly erroneous cooling trends seen in the daily mean analyses for Australia and much of tropical South America arise much more from a decrease over time in maximum temperatures than from a decrease in minimum temperatures. This suggests that the ERA-40 background forecasts (and “analyses”) of daytime (rather than nightime) temperatures are the ones that are biased warm in the earlier years in which we assimilated little or no SYNOP data over these areas.
Western Europe seems to show a slightly larger trend in maxiumum than minimum temperatures. Hotter summers and drier soils? It will be interesting to make more quantitative comparisons with the new data from NCDC.
Best regards

Apparently the problems with ERA-40 were legion and not just in the Arctic. This is from a quoted portion of 5239.txt in conversation with Jones in Feb 2004.
If you are looking for a CO2 greenhouse signal, it should be seen in warmer minimum temperatures as a portion of the heat radiated from the surface into space at night would be re-radiated back to the surface from atmospheric CO2. What they seem to say here is that most of the changes (both up and down) seem to be in daytime highs, not nighttime lows.

Mike Lewis
November 28, 2011 10:55 am

@Tierney – Regarding Ray Ladbury, he has a doctorate in particle physics and works at NASA, if you can believe the NASA information page about him. After the beating I took at RC because I didn’t do the research myself, rather relying on “science-y” websites that have long been refuted (although no citations), I will take the credentials with a grain of salt. After all, I haven’t contacted either NASA or the university to “verify” the claims. Seriously, I don’t doubt them, but I found the environment at RC very stifling. I was labeled “arrogant or an idiot” (my choice!) and my arguments immature because I trotted out the old skeptic arguments and I needed to go back and “learn the science” because everyone knows that Svante Arrhenius proved CO2 will cause global warming 115 years ago. Well everyone except me because I’m an idiot.

Jean Parisot
November 28, 2011 10:59 am

By their own rules, shouldn’t any proxy record that diverges from the temperature record be discarded or at least weighted very low?

November 28, 2011 11:08 am

This piece suggests to me that the core Team had internalized belief, that the world was warming unusually in recent years, and that they were on the case, to such an extent that any evidence against this had to be hidden from the unwashed, their colleagues, and even from their own perception and memory.
I think we have a new piece of Team vocabulary to add to “hide the decline” and “crap“. I read Mann’s use of the word “discuss” in this way:
discuss” a la Mann = distract, deny, obfuscate, blow smoke – thimblerig
discuss time and again” a la Mann = relegate to “Censored” folder in both computer records and personal memory

November 28, 2011 11:13 am

You must understand that according to Mann, people who are vocal about their skepticism “are fundamentally dishonest in everything they do or say” 3399.txt Jan 2004.
So simply standing on one’s convictions, asking questions and demanding they be answered is “fundamentally dishonest”. Who knew?

jim hogg
November 28, 2011 11:15 am

Kaboom says: “If it doesn’t follow the measured temperature record it isn’t a proxy for temperature, end of story.”
If it follows the temperature record until the late 20th C then it might not be the end of the story . . . John L Daly’s comments as recently posted on here helped to put tree ring data into perspective but didn’t invalidate it. . . it might just be that tree ring data v temperature needs closer and more thorough investigation – especially in relation to the late 20th C. Sometimes the answer is right there in front of us and we can’t see it . . .
Given the choice between trusting trees or humans I’d go for the trees every time . . .

November 28, 2011 11:28 am

Given the choice between trusting trees or humans I’d go for the trees every time .

Until someone decides to prank Briffa and rent a small plane and a few bags of fertilizer …

November 28, 2011 11:32 am

Perhaps the whole issue is moot? An interesting e-mail highlighted over at …
From the Climategate 2.0 collection, Tom Wigley e-mails Keith Briffa and Simon Tett (UK Met Office) and pretty much condemns the possibility of quantifying climate sensitivity (presumably to human forcing):
“Paleo data cannot inform us *directly* about how the climate sensitivity (as climate sensitivity is defined). Note the stressed word. The whole point here is that the text cannot afford to make statements that are manifestly incorrect. This is *not* mere pedantry. If you can tell me where or why the above statement is wrong, then please do so. Quantifying climate sensitivity from real world data cannot even be done using present-day data, including satellite data. If you think that one could do better with paleo data, then you’re fooling yourself. This is fine, but there is no need to try to fool others by making extravagant claims.” —

November 28, 2011 11:36 am


Personally, I think that the tree ring records should be able to reproduce the instrumental record, as a first test of the validity of this proxy. To me it casts doubt on the integrity of this proxy that it fails this test.

March 19, 2008
WUWT Bristlecone Pines: Treemometers or rain gauges ?
One of the graphs Steve McIntyre recently produced was this one:
About this graph he notes:

Here’s the MBH98 PC1 (bristlecones) again marking 1934. Given that bristlecone ring width are allegedly responding positively to temperature, it is notable that the notoriously hot 1934 is a down spike.

…It looks like, at least for 1934, BCP’s in the USA desert southwest are better at being rain gauges than “treemometers”. Given “Liebig’s barrel”, it makes one wonder whether BCP’s are a good proxy for temperature at all. Perhaps “Mann’s rain barrel” would be a better name for the MBH98 paper.

November 28, 2011 12:03 pm

This piece suggests to me that the core Team had internalized belief, that the world was warming unusually in recent years, and that they were on the case, to such an extent that any evidence against this had to be hidden from the unwashed, their colleagues, and even from their own perception and memory.

What I am seeing is a pretty typical “fundamentalist” response. So lets say one must believe that the earth is warming at an unnatural pace and that CO2 emitted by humans is the cause. Those are the fundamental beliefs. Anyone calling either of those two issues into question will be seen as attacking their belief, and since they have (as you say) internalized those beliefs, experience any such attack as a personal attack and it will get a “retaliatory” response.
Go into any fundamentalist forum of any sort and question the basic underlying foundation of their particular school of thought and you will be treated in much the same way. They will show you the literature but if you question that, you will be initially dismissed as “just not getting it” or “too dumb to understand” hoping that you will just go away but if you persist, you will be retaliated against. Now the response is quite different in private than it is in public. One thing a person who is on shaking ground wants to avoid is the notion that it is ok to question their fundamental beliefs. This is because if they have to pay attention to you in public, that might encourage others to speak up and heck, if they have to answer your FOIA request, then there might be a flood of other ones!
The reaction I see is one of fear. They are afraid of it being shown that their foundation has cracks in it and they want to discourage dissent in public. The notion that one does not criticize the team/culture/race/religion/country/family/party/tribe in front of outsiders is a pretty well-established pattern of human behavior. So their reaction is saying that they have, in their minds, become a tribe, probably without even realizing they have done so. These people would naturally assume that they are the ones who decide who the “real” climate scientists are (the ones who agree with them in public!). That even shows through in their PR website’s name (“real” climate).

Rational Debate
November 28, 2011 12:04 pm

I haven’t read the comments here yet – but duplicating a comment I left on the climate audit thread:

Severinghaus says:
”But alternatively, he says it is possible that the trees have exceeded the linear part of their temperature-sensitive range, and they no longer are stimulated by temperature. In this case there is trouble for the paleo record. Kieth Briffa first documented this late 20th century loss of response.”

The true irony here is that if this explanation were correct, it would also mean that the trees may have exceeded the linear part of their temperature-sensitive range gawd knows how many times or for what duration in the past also, and therefore failed to show us past temperature increases similar to or worse than that of the past half century.
In other words, this possible ‘explanation’ provided is completely illogical and serves to totally debunk the use of trees as temperature proxies altogether. The only way it can possibly explain the divergence while supporting the use of the proxy is if one uses circular logic and assumes that there was no similar temperature increase during the MWP or any local/regional warming out of cold snaps, etc., which “exceeded the linear part of their temperature sensitive range.” This rational would also imply that by definition the treemometers will provide one with a significantly flattened record that fails to actually follow significant temperature changes.
And unless I’m missing something, the ozone rational is just more flailing around also, since I don’t believe we have any calibrated proxies able to accurately show what the historical ozone cover was over the areas where the tree rings were collected during all of the years each of the applicable tree rings were formed.
It also strikes me yet again just how much these people – I can’t bring myself to call them scientists anymore – waste far more time complaining, rationalizing, scheming, claiming that ‘rotten’ science is so bad it doesn’t deserve a response (without ever saying how it’s supposedly ‘rotten’ of course) and so on, than it would take to just answer the questions, debunk the ‘bad’ science, or respond to FOI’s, etc. That sort of behavior of course begs the question of whether they are at all capable of responding with actual meaningful answers, refutations, or data as applicable.

November 28, 2011 12:06 pm

the thing I have always wondered about tree rings is how are the widths of the rings measured. Is it done manually with calipers ? is it done using a microscope with a “yardstick” of some sort … How much “skill” is involved with these measurements and how much is dependent on the same person measuring every ring in a climate controlled environment … How big are the error bands of these measurements … since we are talking about very small sizes even a slight error would make a huge difference …
Does anyone publish their raw ring measurements ?

slow to follow
November 28, 2011 12:15 pm

For JeffC:
I think winDendro was disscussed at CA a while back.

November 28, 2011 12:24 pm

Severinghaus said: “Personally, I think that the tree ring records should be able to reproduce the instrumental record, as a first test of the validity of this proxy. To me it casts doubt on the integrity of this proxy that it fails this test.”
In other words, the whole idea of using tree rings as a proxy has apparently been falsified. I wonder if there have been any further tests of this proxy; it should be easy enough to do a proper double blind test today. I mean, we have loads of trees and instrumental temperature data galore.
I would be very surprised if the researcher got it right.
Perhaps “hide the decline” really means “hide the unfortunate falsification” …

November 28, 2011 12:31 pm

But here are the “lies” in Mann’s entire paper – in the entire hockey stick illusion that the IPCC used 7 times to create their CAGW scenarios with the very willing support of the Team and their hand-picked poor-reviewers in the CAGW-sponsored so-called “scientific” literature.
1) We KNOW – absolutely – from the satellite measured data for actual global temperatures – that global “average” temperatures (assuming such actually exists in any case) that the world’s temperatures randomly and irregularly jump and move up and down by 0.2 degrees while CO2 steadily rises. No, we don’t know “why” the global temperatures changes by 0.2, but they are measured as changing.
Therefore, any reconstructed data over any period of time must included that variation – regardless of ANY other measure or proxy, the actual temperatures are changing by that much, so even before any other error bars from the proxy analysis itself, the actual temperature can never be plotted or determined more accurately than +/- 0.2 degrees in any given year. Or over any given period.
2) Mann’s (MBH98, 99 and all their follow-on “studies) failed to even plot their own data properly: Their own graph shows clearly the Medieval warming Period and Little Ice Age. On of their graphic conclusions is the grey line: at 1500 AD, their line is decreasing from -0.80 degrees. Their own data at 1500 AD? -0.30, with a very small std deviation. They are 1/2 degree wrong in their own paper, their trend line (the slope at 1500 AD) is opposite of what is determined by their plot, – and they are proud of their results and are determined to defend their results?
3) Look at their own data through every century. If they ever release their data and their methods, maybe we could actually plot real std deviations, but use the variation between lines to judge the trends between of their proxy studies for the following.)
800 AD. -0.50 degrees high std dev.
900 AD -0.30 degrees high std dev.
1000 AD -0.25 degrees very low std dev.
1100 AD -0.20 degrees very low std dev.
1200 AD -0.35 degrees very high std dev.
1300 AD -0.30 degrees low std dev.
1400 AD -0.30 degrees high std dev.
1500 AD -0.35 degrees very low std dev.
1600 AD -0.75 degrees low std dev.
1700 AD -0.55 degrees high std dev.
1800 AD -0.60 degrees very low std dev.
Mann is showing his own MWP at -0.30 degrees within very small error bands, and the LIA at around -0.75 within somewhat higher error bands.
But that result doesn’t match what he wants – what the team needs to push their religiously fervent dogma on their public.

November 28, 2011 3:07 pm

crosspatch says:
November 28, 2011 at 12:03 pm

yes… sigh… Scientific fundamentalism, fear [by the Team] that is not even recognized as fear… because Science is so disused to observing the evidence from the half of reality that Science once tacitly agreed is no reality… because if Science were to claim inner reality as reality, then the Church would squash them out of existence… so the early scientists decided that half a loaf was better than no bread…
Now we reap the consequences. But seeing this is also the way forward. What makes WUWT and CA and all the rest so riveting is that we know that here, the fullness of humanity and integrity is not just respected but expected, and recognized as fundamental to good science.
At least some Christian fundamentalists have experienced transformed lives and miracles of healing – I’ve met them. That is more than the fundie scientists can say, unfortunately.

Chris B
November 28, 2011 4:50 pm

Maybe the word fundamentalist has a new meaning, To think of ways to pervert research in order to secure funding.

November 28, 2011 5:13 pm

“To think of ways to pervert research in order to secure funding.”
No, that’s an enviroclimagrantologist.

November 28, 2011 5:25 pm

More cracks in the foundation of ‘The Team’. I look forward to the ‘coming out’ as the walls crumble.
Will some reveal their own emails to prove they were wrongly held captive by ‘The Team’? This could be a block buster show.
We may ultimately have to determine who the the ‘turn coats’ are. The Outlaw Josey Wales comes to mind with the guy operating the ferry.

November 28, 2011 6:47 pm

My own response is more cynical. I’ve seen this sort of snowjob in the humanities as well, and the person behaving a la Mann is not necessarily a ‘fundamentalist believer’ in global warming or his own science: quite the opposite. Crosspatch, Lucy, and others. you have got the source of Mann, Jones et al.’s fundamentalism wrong. The fundamentalism they display is to serve the anti-humanist ’cause’ at all costs – especially since there’s a lot of money to be made for them. The cause is political, not scientific: to punish selfish consumers of the developed world and selfish breeders of the developing world for their sins against Gaia.
When I see a snow-job like Mann’s responses to Severinghaus, my instinct is to think that Mann does not believe what he is saying to Severinghaus, but that he is trying to distract Severinghaus from focusing on the naked truth about Mann et al.’s attempts to simulate science. Mann is a fundamentalist believer of grants and his ability to wrest fame from science and influence policy: ie. he believes in his own power.
Somebody who lies like Mann is not a ‘religiously’ fundamentalist believer in his own science. You do true religious fundamentalists a discredit here, because fundamentalist Christians, for example, by and large are not ardently engaged in the duplicity combined with self-deception and self-aggrandizement embodied in Mann (unless you have in mind the equally fake televangelist scammers).

November 28, 2011 6:54 pm

The tree rings should be able to replicate which temperature record?? Satellite, ground, raw, adjusted, global, local…????

Christopher Hanley
November 28, 2011 7:29 pm

Kaboom says:
November 28, 2011 at 10:02 am
If it doesn’t follow the measured temperature record it isn’t a proxy for temperature, end of story.
Oddly the decline shown in Briffa 2001 ( does have some resemblance to the measured N
H record as published in 1968 ( and 1976 ( hemisphere temperatures/NHNatGeo76small.jpg), i.e. the mid-60s in a trough about as deep as c.1900.

Christopher Hanley
November 28, 2011 7:30 pm

That second link: hemisphere temperatures/NHNatGeo76small.jpg

November 28, 2011 8:52 pm

Still, it looks to me that the other researchers did not hide their decline, and that their proxies follow the measured temperature for a while after 1960, even accuratly describing a temporary short downward inflection at the end – great modelling really, Only in the most recent years did the observed temperature catapult away from the treerings. the fact that mann hid his declining results does not detract from the general idea of the hockey stick or am I missing something. For me the questions are 1) why the divergence between measured and proxy in recent years and 2) why do the proxy results of different researchers converge towards the present time ? ?

Gail Combs
November 29, 2011 3:39 am

Jimbo says:
November 28, 2011 at 11:36 am
Personally, I think that the tree ring records should be able to reproduce the instrumental record, as a first test of the validity of this proxy. To me it casts doubt on the integrity of this proxy that it fails this test.
March 19, 2008
WUWT Bristlecone Pines: Treemometers or rain gauges ?
One of the graphs Steve McIntyre recently produced was this one:
I would think GROUND temperature is the deciding factor for temperatures. Seeds do not sprout and crops do not grow until the ground is warm enough after that it is nutrients, sunlight, length of day and rainfall that are the factors. Some plants, mainly annuals like rye or pansies, have an upper temperature limit but most plants tolerate a wide range in temperature and still grow if there is enough rain and sunlight.
Once the GROUND is warm enough, I would think water, sunlight and nutrients are the deciding factors with water (rain) being the most important. You are not going to get a growth spike from nutrients without adequate rain fall, and the rain has to have a reasonable distribution. Drought all summer with a few hurricanes dumping several inches is not the same as gentle rain a couple times a week.
The only reason I can see for trees to correlate at all with temp is because the ocean cycles link to wind patterns and you get warm/wet vs cool/dry or whatever at various locations as the wind patterns change. (Stephen Wilde’s “loopy Jets” and El Niño/trade winds)
El Niño and Trade Winds:
You also can not leave out the sun and cloud cover.

Trends in daily solar radiation and precipitation coefficients of variation since 1984
David Medvigya,b and Claudie Beaulieub a Department of Geosciences
b Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ
This study investigates the possibility of changes in daily-scale solar radiation and precipitation variability. Coefficients of variation (CV) were computed for the daily downward surface solar radiation product from the International Satellite Cloud Climatology Project and the daily precipitation product from the Global Precipitation Climatology Project……
We conclude that there have been detectable changes in high-frequency solar radiation and precipitation variability over the past few decades. Changes in solar radiation CV were large and positive for tropical Africa and the Maritime Continent (Fig. 3)….These continental locations where we detected changes do not overlap with the mainly oceanic regions where trend detection is sensitive to long-term changes in satellite geometry (Evan et al. 2007). Although we also detected negative trends in solar radiation CV at high latitudes (Fig. 3), these high latitude trends should be regarded with caution because sampling errors and cloud detection errors are much larger there than at lower latitudes.
Solar radiation CV was correlated with precipitation CV and deep convective cloud amount throughout much of the tropics. In particular, the Maritime Continent and tropical Africa had significant increases in all three quantities. Links between convective activity over continents and temperature have already been suggested (Del Genio et al. 2007). It is notable that changes in deep convective cloud amount (and solar radiation CV) were much lower over tropical oceans than tropical land…. The possibility of a causal relationship between deep convective cloud amount and solar radiation CV and precipitation CV requires further study.
We expect that increases solar radiation CV will decrease the productivity of terrestrial ecosystems (Medvigy et al. 2010). Photosynthesis increases with insolation, up to a critical point, and then the response saturates. An increase in the number of low insolation days will therefore reduce photosynthesis, while an increase in the number of high insolation days will have little effect. ….
or at WUWT:
If you want to use plants as thermometers , use the change in species northern most range. Grapes in England and Wheat in Russia/Canda for example…. or tomatoes. (snicker) We all know tomatoes make great thermometers.

November 29, 2011 5:03 am

Mr. Moderator,
You should be informed that the Facebook box in this posting overlaps the graph next to it. The box insists on being bigger than the margin all other ads are living in.
This is very aggravating as ti covers the 20th century which is the part of the graph being discussed.

November 29, 2011 7:50 am

@Rational Debate
Just a note on your comment on the Severinghaus quotation — he does not necessarily share in the ‘illogic’ of The Team in the use/misuse of paleo records, since one part of his quote does include the (somewhat cryptic) remark that “In this case there is trouble for the paleo record.”
In other words (unless I am misreading his admittedly brief remark), he may be gesturing toward “trouble” in potentially many eras of the paleo tree-ring records and not only toward a contemporary time-frame. At least, I have not seen where Severinghaus believes or assumes that the paleo tree-ring approach has been validated across centuries and millenia of data.
In any case, my comment has no bearing on misbehaviors of The Team etc., it’s simply pointing out that Severinghaus does not seem to share in their outlooks and behaviors from what we have seen so far…. (???)

November 29, 2011 2:12 pm

vigilantfish says: November 28, 2011 at 6:47 pm
ok let’s do best scientific practice between us. Your criticism alerts me to distinguish between Jones whom I regard as principally a fundie believer, temperamentally vulnerable to the nasty intensification of Milgram programming (do read up Milgram, it’s quite a revelation); Mann whom I regard as an egotist, bully and serial liar, for whom fame was the prize to keep at all costs, and Trevor Davies whom I regard as the money-grabber. Davies the Dosh needed Jones the saintly front. Penn State needed Mikey the showcasing showman. So – imo the Team has a full range of science-obliterating characteristics from saintly fundies to fear-based greenies to bullies, whose common language looks like salvational science; their roadies are the money people whose spoken line is “we know AGW is probably real, but we need the research to nail this to help us establish global limits; can you sciency people help us?” and whose unspoken line is “always stay one step ahead of the others, if you want to make money”
That better??

November 29, 2011 2:40 pm

@ Lucy Skywalker:
Thanks for reminding me about Milgram. I am a great admirer of your comments and am willing to concede game, set and match to your masterful and insightful analysis. I had been inclined to see Jones and Mann as the obverse US/British sides of one coin, but you have been following this story with great dedication and obviously have detected nuances which have passed me by. If the Milgram context applies to Jones, how much moral culpability does he carry? Authority is a powerful moral neutralizer for the weak, which is what Jones would be if this were the case.

November 30, 2011 12:59 am

An important source of nutrients for plants is airborne dust. In the industrial era this included particulates from burning of coal and other fuels. These particulates increased until around 1960 then decreased as clean air acts were introduced in the developed world.
This explains the rapid rise in tree ring proxy derived temperatures through the late 19th and 20th century and the decline post 1960.
It also explains the divergence post 1960 as decreasing particulates and aerosols substantially caused the rise in the thermometer temperature record, by causing an increasing Tmin due to increased early morning insolation (in the absence of aerosols/particulates aka smoke and haze).
If I am right there should be a large divergence in tree ring trends between places like the USA, Russia and India.

December 5, 2011 1:44 pm

I think what everyone missed in Mann’s work was the “and then a miracle occurs”, which completely explains the divergence between the proxy and the actual temperature.
Or it could be that the bristlecone pines are racist deniers. I can’t decide which.

December 9, 2011 4:01 am

If the past and present can be manipulated, the future can be manipulated.

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