FOIA – Select UV and Tree Rings

I did a search on ” UV ” that turned up several pages. The general theme was an awareness that UV mattered, but lack of clarity about how it matters. Often with a bit of a dismissive tone, but recognizing there was some loose end there to tie up.

I’m not putting all the emails in this posting (as it’s more than I can do right now, and probably not all that interesting). I’m just going to pull out 3 in particular. Why them? First off, they show an interesting thing about UV and tree rings. Second, they show the mind set of “when it doesn’t fit, cut it out”…


If you would like to read any of these emails, just hit this link and pick out the email that has the same number/name:

Link to online archive of emails.

For a general entry point into prior FOIA postings, look here:

Each of the articles on a F.O.I.A. topic will be assigned to the FOIA Category (at the right edge of the page). You can get directly to that list (which will be in reverse chronological order) here:

Of UV and Tree Rings

[ This one is interesting as it gives a nice laundry list of things they know are wrong with the present method of using tree rings. UV is included on the list. So much for that whole “settled science” meme… -E.M.Smith ]


date: Wed Oct 14 13:51:06 2009
from: Tom Melvin
subject: Finland Conference
to: Keith


By June we are unlikely to have the long Eurasian paper ready to discuss.
Would it be better for you to present on Divergence e.g.


1. Problem with curve-fitting e.g. Hugershoff (Briffa 1998) and trend distortion – part solution Signal free.

2. Problem with mixing sloping and horizontal curve fitting in Arstan (e.g. D’Arrigo 2004) – part solution RCS.

3. End effect problems with RCS (Briffa – Hughes book) – e.g. sample bias

4. Problem with updating chronologies (TTHH and Grudd 2008, Tornetrask)

5. Potential problem with Crown dieback (e.g. responders / non responders)

6. Potential MXD in sapwood problem ????

7. Potential competition problem – tree density changes RCS shape (Helama 2006)

8. Problem with non-linear response / skewed index distribution (Barber, Wilmking etc)

9. Remove all these and residual is real divergence – problem with identifying cause:
CO2 change / Nitrogen fertilisation / Global dimming / UV light / Drought stress/

Conclusion – Lots of work to do to clarify situation.

I would present on PBS//GUESS work.

We need to prepare abstracts in next week or so.



[ In this one a Russian researcher raises the UV question (in that particularly endearing way a Russian Professorial Voice has of making you feel slightly chided, while having an air of cautious precision, while leaving out the word “the” all the time ;-) Still, it is a rather important point: UV swings wildly. If trees react to it, what are they really saying about temperature? Briffa, or course, attributes recent UV rise to environmental reduction of Ozone. Someone needs to point him at solar UV changes… -E.M.Smith ]

date: Mon Feb 4 09:56:12 2002
from: Keith Briffa
subject: Re: Tree growth/ uV link?

to: “Svetlana Bondarenko”

Dear Professor Zuev
I am very interested to see that you are also looking at the possibility that uV radiation increases at high latitudes might be impacting on tree-growth. Along with several colleagues here and in Switzerland (Fritz Schweingruber) , along with Academician Vaganov and Professor Shiyatov from your country, I have been very interested in the apparent changing relationship between measured tree growth (ring width but particularly ring maximum density) and summer temperature – not just in Russia but also in other relatively high-latitude or high-elevation sites in the U.S. , Canada and Europe. We have established that there is a slow change , with the link between these data weakening over the last 50 years , but year to year changes on a large scale staying parallel. I have suggested in several conferences and in press that higher uV (as a consequence of reduced total ozone ) may be factor , but this is speculation based on some reading of the physiological literature that suggests that photosynthetic processes may be impaired in high uV experiments.

There is also the coincidental observation of reducing ozone at some long record sites (such as Arosa) since the 1950s. However, other environmental variables, e.g. the atmospheric clarity, also show negative trends over this period, so there can be little statistical evidence offered . We have though tried looking in some detail at the association between temperature residuals (that is the difference series between our empirical estimates of temperature change as calculated from tree-growth , and observations of summer mean temperatures) across the different parts of our network , and variations in total ozone as extracted from the TOMS satellite data . This is intriguing but not convincing ( we would hope to see a positive correlation ) – but in many areas our tree-ring data (especially the density data) do not come up to the present and the satellite records are short (only from the late 1970s) so again our degrees of freedom are low for this comparison. This later work is not published but I will send a few references to our earlier papers , and in the meantime I will read the text that you have sent me. Please be a little patient as I am very bogged down with several passed deadlines and teaching at present.
Very best wishes
At 03:21 PM 2/1/02 +0800, you wrote:

Dear Doctor Briffa,

Quite recently, our results concerning the reconstruction of paleobehavior of ozonosphere from dendrochronologic wood density data were presented at the international conference «Ecology of Siberia, the Far East and the Arctic» in Tomsk, and a little later at the Sukachev Institute of Forest in Krasnoyarsk. These results have stirred real interest. Academician Vaganov, Director of Institute of Forest, referred to your papers, and prompted that it is you who pointed out to some mismatches appearing between dendrochronologic time series and temperature/precipitation variations, and who related dendrochronologic data to some other parameters such as ozone concentration. May be our results will be of interest for you. So, we send you a translation of our paper published in:

Environment of Siberia, the Far East and the Arctic: Selected papers presented at the
International Conference ESFEA 2001, Tomsk, Russia. September 5-8, 2001. P 3-12, V. V.
Zuev and Yu. P. Turov, Editors.

We would be indebted if you respond to our results in order to bridge scientific contacts in development of this branch of dendrochronology. Academician Vaganov, who discussed this problem with us, also considers it useful to contact you. Our research area is the study of stratospheric changes using the laser sensing methods, primarily by studying the changes in ozonosphere (Laboratory of Remote Spectroscopy of the Atmosphere, We are strongly interested in problems of natural variability of ozonosphere. Unfortunately, in the field of dendrochronology, we are only making first steps, having few sources of the corresponding dendrochronologic data. In particular, from the paper it is clear that ozone is found to be most strongly correlated with density of Stone Pine in Arosa, Switzerland; whereas other data for this tree species for other geographic regions are very difficult to find. Possibly, there may be some other types of sensitivity to the effect of UV-B radiation. We would be very indebted if you give us the corresponding bearings in this direction.

Prof. Vladimir V. Zuev,

Corresponding Member of the RAS

Svetlana L. Bondarenko,

postgraduate students


[ I find this one sort of funny / sad. He has the “sudden appearance of moisture sensitivity”… New Flash from Farm Country: Trees are ALWAYS sensitive to moisture to some degree, but if some OTHER factor was limiting and is now gone, it will ‘suddenly show up’. Learn a bit more about farming and forestry and you would now about Rate Limiting Nutrients and Liebig’s Barrel. One could also ask if they are aware of the way that enhanced CO2 levels cause a more robust response to water stress and the whole idea of CO2 fertilization. So those local variations in CO2 over time DO matter. -E.M.Smith

date: Wed Apr 30 15:57:27 1997
from: Keith Briffa
subject: Re: your note and CAPE
to: (Gordon Jacoby)

I too am not sure where we left our conversation last. Yes I couldn’t agree more about PAGES and the million spawning devils that seem to be the product. Somewhere there has to be a balance between self interest and Science good – both for PAGES and the individual- but at the moment I don’t know where. There is going to be a CAPE project document and there is supposed to be a high-resolution aspect and Greg Zielinski and I are supposed to organise it. At least we should put in why tree rings are important but what good that does the dendro community I’m honestlty not sure.

But to go to science – surely you have talked to Ed about the work I’ve been doing trying to document and understand the change in sensitivity of northern density (and ring widths) to temperature. I have a manuscript but the problem is a major one and is complicated by the issues of CO2 , temperature thresholds,standardisation regional coverage(i.e. spatial scale),appropriate climate signal etc. etc. Simply we see a loss of decadal scale sensitivity in much of our large spatial average data – and in our recent Russian calibrations. I know you talked about this in a couple of papers and have suggested a recent appearance of moisture sensitivity in your northern American trees. I do not know why this is happening but it seems clearer in the density data. We (at least Fritz) has explored the technological possibilities – i.e. that density is biased by an inability to record maximums correctly in very narrow rings but we do not believe this to be the case. I think some threshold may have been crossed that means the densities are limited in their ability to record high temperatures and of course it could be a drought type response in warm periods. These suggestions do not seem to be the answer – or at least all of the answer. Similar warmth before and less of an underprediction of temperatue then, plus the widespread (though not perfectly synchronous) manifestation of the phenomenon lead me to suspect synergistic influences. I really think that nitrates,CO2.tropospheric ozone – and ,certainly not least,
increased uv could each or all be playing some part.
As for calibrating transfer functions , I think we have to somehow adjust recent tree growth records or not use recent data in the calibrations!
Please would you send me copies of your 1995 paper with Rosanne in Woodwell and Mackenzie,Eds. and the 1991 paper in the Fairbanks meeting proceedings, please.
I will fax you a page from the EC report that went to Brussels in March. It refers to these points. Also did you know that you were criticised in a recent paper by Lloyd and Farquhar?(Functional Ecology, 1996,10,4-32.
I am trying to get a backlog of stuff out , including our maps of degree day reconstructions in Russia and a short and a longer paper describing the stuff above. At the moment I would be happy if you did not therefore distribute the page I am faxing or this information until I can at least get the manuscripts sent off. We must also talk at length about PAGES and CAPE but I haven’t got the time or stomach for it now!!

as always best wishes to you

At 16:45 29/04/97 -0500, you wrote:
>I am not sure where we are in our conversation. I thought you had a few
>more comments about my comments.
>Anyway, about your comments on PAGES, etc. That is exactly the issue I was
>raising, about CAPE becoming just a second generation of PALE. These narrow
>initiatives are an abomination unless it is something unique like the
>ice-core program. Why is paleoclimatology evolving into so many sub-systems
>and acronyms. Many of them might fit under World Atmosphere Studies Toward
>Environment and Circum-Arctic Studies of Holocene. One cynic who had a
>brief fling with PAGES thought it was just an additional layer in the
>bureaucracy of science. I am not sure I agree with him but the
>proliferation of commitees under PAGES seems in danger of going out of
>control. Eventually each paleoclimatologist will have their own committee
>under GOTSUM (Group Organized To SUpport Me) CAPE should be broadened to
>cover more with a single committee and replace some related groups.
>On a more productive science note: I have begun some analyses of the data
>from our Taymyr chronologies and there is a noticeable change in response
>to climate in recent decades. It is not as clear as the Alaska spruce
>situation exactly what is happening but one cannot make simple models
>assuming a constant relationship. I would assume you are aware of this and
>wonder what your thoughts are.


In Conclusion

So UV levels can modulate tree rings? And we know that UV changes enormously over the solar cycles, especially during Grand Solar Minima. Here we see that Briffa knows of the effect, but does not allow for it in his past temperature reconstructs. We also know that UV went high during the recent solar max (as he struggles with a recent ‘divergence’…) and has plunged in the current minimum.

I think this illustrates a very significant problem with using “Treemometers”… They are also solar UV gauges…

Then there was a whole host of other confounding factors given. At the end, they are surprised that there are “issues” with divergence? I think they really ought to be asking “Does the past really have a correlation?” To me it all looks pretty clear: Trees respond to the totality of their environment, and attempts to use them as a Treemometer require knowing EVERYTHING ELSE completely. As we don’t know those things, trees are not reliable for temperature ‘reconstructions’. Oh, and “UV Matters and varies a lot with solar state.”

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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3 Responses to FOIA – Select UV and Tree Rings

  1. Ian W says:

    If one has spent the majority of one’s adult life going on expeditions to remote places, carefully recovering core samples, analyzing the samples by a ‘set of metrics’ then using statistics to turn those metrics into results followed by fighting your papers through peer or pal review, I can see why it would be upsetting to read the ‘law of the minimum’. The sudden realization that all was in vain could make one quite ill – or viciously defensive.

    Perhaps these PhDs should have obtained advice from a few farmers – it would have reduced their travel budget.

  2. adolfogiurfa says:

    If….Chronologies are all wrong, then…..the history not only of trees but of man is to be revised.

  3. kakatoa says:

    Speaking of trees, rain and snowfall-

    “LAKE TAHOE, Calif. (KGO) — Scientists in the High Sierra have discovered a previously unknown forest, and there’s a twist. The ancient trees in this forest are under water. They are standing at the bottom of Fallen Leaf Lake, just south of Lake Tahoe. New research shows both the forest and the lake hold critical clues to climate change.

    Fallen Leaf Lake is already known for its spectacular beauty. Now it turns out the lake also has a dramatic secret.

    “What I like to call a ghost forest,” says Prof. Graham Kent of the University of Nevada, describing trees up to 100 feet tall, as high as a 10-story building, but covered by water. “We have old wood from a thousand years ago, 2,000, 3,000 down there.”

    Scientists in a small submarine took photos showing just a few of the hundred or more trees on the bottom of the lake. They’re using state of the art sonar to map the mysterious forest and try to figure out why it’s there.

    “Side scan sonar technology is exactly the equipment that’s used to find sunken ships,” says Kent.”

    I concur mostly with your “To me it all looks pretty clear: Trees respond to the totality of their environment, and attempts to use them as a Treemometer require knowing EVERYTHING ELSE completely.” It is hard to know anything completely- but I agree with “the totality of their environment” part of the comment.

    I have been trimming some fig trees the last few days and it looks like moisture is the primary driver in my fig tree growth not small change in temperature.

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