It seems that Columbia’s Rosanne D’Arrigo thinks Mann’s tree ring study isn’t representative proxies for volcanic eruptions, nor good for dendrochronology, though Mike Mann seems to think so. This Twitter interchange via Alexandra Witze from the AGU Chapman Conference on Volcanism and the Atmosphere in Selfoss, Iceland 10–15 June 2012 tells the story:
And Witze goes on to say that there’s a rebuttal paper in the works, but Mann is not amused. Mann responds (TRW means Tree Ring Width):
I still don’t think Dr. Mann has a basic handle on Liebigs Law.
Its seems a rebuttal is in the works
(h/t to Tom Nelson)
Here is what the Twitter fight is all about, this paper published in February:
Abstract from Nature Geoscience here
Underestimation of volcanic cooling in tree-ring-based reconstructions of hemispheric temperatures
Michael E. Mann, Jose D. Fuentes & Scott Rutherford Nature Geoscience (2012) doi:10.1038/ngeo1394
- Received 14 June 2011 Accepted 11 January 2012 Published online05 February 2012
The largest eruption of a tropical volcano during the past millennium occurred in AD 1258–1259. Its estimated radiative forcing was several times larger than the 1991 Pinatubo eruption1. Radiative forcing of that magnitude is expected to result in a climate cooling of about 2 °C (refs 2, 3, 4, 5). This effect, however, is largely absent from tree-ring reconstructions of temperature6, 7, 8, and is muted in reconstructions that employ a mix of tree-rings and other proxy data9, 10. This discrepancy has called into question the climate impact of the eruption2, 5, 11.Here we use a tree-growth model driven by simulated temperature variations to show that the discrepancy between expected and reconstructed temperatures is probably an artefact caused by a reduced sensitivity to cooling in trees that grow near the treeline. This effect is compounded by the secondary effects of chronological errors due to missing growth rings and volcanically induced alterations of diffuse light. We support this conclusion with an assessment of synthetic proxy records created using the simulated temperature variations. Our findings suggest that the evidence from tree rings is consistent with a substantial climate impact2, 3, 4, 5 of volcanic eruptions in past centuries that is greater than that estimated by tree-ring-based temperature reconstructions.
a,b, Estimated average length of the growing season (number of days of non-zero growth) based on the biological growth model driven by the GCM simulation without stochastic weather forcing (a) and with stochastic weather forcing (b). c, Forcing missing
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Why does that idiot keep thinking temperature is causal? I keep looking for temperature in the Kreb cycle and I just can’t find it.
So let me clarify.
– A massive blip temperatures caused by natural phenomena does not show up in tree-ring proxies.
– Tree ring proxy-based reconstructions show that C20th warming is greater than anything in the past 1,000 years.
– These reconstructions are then fed into climate models that try to estimate the influence of known forcings such as solar, CO2 – and volcanic activities. (See Gergis quote below)
– As the biggest fluctuation in the reconstructions is the C20th uptick, and the only extreme phenomena in C20th not present in others centuries is the increase in greenhouse gas levels, then anthropogenic forcings are the major recent driver of global warming.
Like with the post 1960 decline in tree-ring proxy temperatures, Mann, Fuentes and Rutherford show that tree ring proxies fail to pick up known global temperature fluctuations. By implication, they provide further corroboration for claims that climate models exaggerate the influence of CO2.
From Gergis et al. 2012 abstract
So this is what “science” has come down to:
“We support this conclusion with an assessment of synthetic proxy records created using the simulated temperature variations.”
SO we synthesize proxy records? What about all the other variables? Sunlight, moisture content, particulate matter…….. all the others I can’t come up with…….
I wonder if Mr. Mann uses models to predict how his day is going to go, or week, or month or year?
Here we use a tree-growth model driven by simulated temperature variations to show that the discrepancy between expected and reconstructed temperatures is probably an artefact caused by a reduced sensitivity to cooling in trees that grow near the treeline.
Yeah, it couldn’t be that the model is wrong, now could it?
/sarc
Models all the way down.
Heck, Anthony, the yield of plants is so much more complicated than we imagine, way past Leibig’s Law. For example ,it is known from controlled studies that some elemental nutrients like molybdenum and zinc also interact with pH (which is on a log scale) and that pH interacts with the availability of calcium or vice versa, which can affect the solubility of some relevant molybdenum compounds. Even common old iron has problems being ferric or ferrous, a chloride, an oxide a suplhate or a synthetic chelate. It’s a fun game to find the dependent variable sequence and also the number of interacting variables in a particular biochemical cycle and also whether they interact on a linear basis of concentration or a curved one, even an inverted U.
Climate workers have this fixation with relating all and sundry to temperature, to the detrimental neglect of old-fashioned chemistry and physics. That’s strange, because they can’t even describe why their own bodies maintain almost constant temperature (without periodic historic adjustment), but they are very wise about tree rings.
If one removes all the “tree-ring reconstructions” “tree-growth model” “driven by simulated temperature variations” “reconstructed temperatures” “probably an artefact” “assessment of synthetic proxy records” “simulated temperature variations” is there anything real left in this paper, or is it merely a mental exercise with no real-world data whatever?
braddles said (June 15, 2012 at 12:38 am)
“…People are trying to rebut and debate scientific papers using 140-character Tweets? What is going on in science? I don’t care who is right, this is insanity…”
In Dr Mann’s case maybe all his “climate science” papers should be limited to 140 characters.
Harder to get things upside-down that way.
“Skeptical empiricism, the kind exemplified by the carefully thought-out and tested research in science at its best. It differs from plain empiricism” — which is simply the observation of results of the world around us. Put more simply, it is important for us to be skeptical about the world around us and not blindly accept what we believe to be “truths.”
Gerald Holton, professor of physics and the history of science, Harvard University
Now, a comment about the paper itself:
From the abstract – “…The largest eruption of a tropical volcano during the past millennium occurred in AD 1258–1259. Its estimated radiative forcing was several times larger than the 1991 Pinatubo eruption. Radiative forcing of that magnitude is expected to result in a climate cooling of about 2 °C. This effect, however, is largely absent from tree-ring reconstructions of temperature…”
Considering that most tree ring reconstructions used carefully selected data designed to show the RECENT warming (CAGW), it’s no wonder that they failed to catch any past variation.
Sounds like he’s trying to defend the handle of the stick, here.
I’ll bet that if they re-screened their tree data, they’d find LOTS of trees that show an effect from this eruption.
Of course, those trees probably wouldn’t show the current warming.
Handbags at dawn …
Pointman
Should have seen this the first time:
“…We support this conclusion with an assessment of synthetic proxy records created using the simulated temperature variations…”
They used synthetic proxies and simulated temp variations to prove a point?
No wonder people question the methods used by “climate scientists”.
I await the “War with Posters” with heart aTwitter (sic). Can’t believe PSU is paying Mr. Mann to put out ridiculous tweets calling others names. GET A JOB.
Sort of on a tangent, my heart is warmed by seeing a Science News correspondent question something from the warmists. I’ve subscribed continuously since 1969, and credit them for being able to talk with pretty much any scientist without wasting his time. Unfortunately, their environmental reporter and blogger is active in the Society of Environmental Journalists, which had been strongly warmist activist (see http://www.sej.org/initiatives/climate-change/overview ). They seem to have tempered things a bit after Rajendra Pachuri was the keynote speaker at their annual meeting. I haven’t followed the SEJ too closely so I can’t point to specifics. I did invite her to the ICCC in Washington last year, but as far as I know, no one from SN attended.
I and others I recognize from WUWT have commented on some items in the SN blog that are uncomfortably one sided. They’ve deleted a couple of my comments (I think they don’t like my Eisenhower references about gov’t funded science and policy), but sort of tolerate me.
It’s frustrating seeing their AGW bias, but I did renew for a couple extra years last month as it remains a very good springboard to current developments, especially with their reports from conferences.
Gotta go find a contact address for Alexandra Witze and send her a thank you note. SN doesn’t make it easy and I’m not joining Twitter.
g3ellis says:
June 15, 2012 at 3:03 am
> I keep looking for temperature in the Kreb [sic] cycle and I just can’t find it.
The Krebs Cycle describes the chemical steps of metabolism. It doesn’t describe the rate, and anyone looking at the Kreb cycle should be aware that temperature affects the rate of many enzymes.
Yes, I understand you’re being sarcastic, but that’s no reason to feign ignorance.
Also, The Kreb Cycle is only indirectly related to the Krebs cycle, see http://krebcycle.com/ 🙂
OK, folks, welcome to the world of science. You may not have known this but scientists disagree with each other all the time. Hence why the idea of “they” and “them” working together on a “climate agenda” is so ridiculous from a scientist’s perspective.
Mann and D’Arrigo are both having a healthy scientific debate. They’re doing so at the AGU scientific conference, with some spill over onto Twitter (with such scandalous language as “terribly dishonest” and “misleading”). But the real scientific debate is in the peer-reviewed papers, where it should be.
Note to Mike – be careful how much you debate volcanoes with Witze, read http://scicom.ucsc.edu/about/program-news-articles/2012-01-witze.html and she has a geology degree from MIT, http://www.environmentwriter.org/scienceandthenews/bios/awitze.htm .
Knowing Mann’s propensity to be unable to keep his mouth and Twitter account shut, this could get very entertaining, very fast! Popcorn, anyone?
tonyb, thanks, very interesting!
Maybe Mann can put the sum total of his relevant science in a single Tweet. Or maybe not.
To tweet or not to tweet, that is the (scientific) question.
(I’ve never seen anything so absurd–Mann is off his tweets.)
Liebig’s Law
Lie Big and carry a hockey stick.
henrythethird says:
June 15, 2012 at 4:32 am
I’ll bet that if they re-screened their tree data, they’d find LOTS of trees that show an effect from this eruption. Of course, those trees probably wouldn’t show the current warming.
=========
Exactly right.
At one time, the best indicator of the stock market was the height of snowfall in a small mid-western town. For decades. lots of snow that winter, the market went up that year. Very little snow, the market went down. Using the “screening” approach common to climate science and most of the social sciences, for some unexplained reason the market recently diverged from the snowfall records. Probably a result of CO2 contamination.
These sorts of accidental correlations occur all the time. If you start with a big sample of trees, you will always find some trees that match anything you want. Be it temperature or the stock market. That doesn’t mean that these trees will match anything outside the study period. Unless of course they happen to support the conclusion you are trying to promote.
What we are seeing in the long sad history of tree ring “science” is nothing more than phrenology. Predicting intelligence based on the number of bumps on your head, as a result of studying only those people where the bumps do match intelligence. Those people where the bumps don’t match? We leave them out of our study using a screening process called “calibration” in which we calibrate the bumps to the subjects intelligence.
Dr. Mann seams to be a bit of a Twit.
So scientists disagree. Yep!
So a health discourse is going on in climate science. Great!
Once you get passed the Mann bashing there’s much here that undermines those that believe the climate science community is involved in some sort of collective confirmation bias process.
“..Promises fireworks at poster session.”
Sounds like someone is making a death threat against a climate scientist. Actually, it does sound like a threat is being made. Who was the person making the promise? They appear to be making a threat.
I want to highlight one of Michael Mann’s tweets reproduced above:
========================================================
Michael E. Mann @MichaelEMann
@alexwitze D’Arrigo claim our study provides fodder for #climatechange #deniers terribly dishonest. Its just the opposite [cont] #AGUVolcAtm
========================================================
Even in this strange shallow Twitter world, it is stunning when one prominent scientist calls another “terribly dishonest” — it’s not even clear why it would be a question of honesty, since the point about what may provide “fodder” for evilllll climate change skeptics really gets more into a grey area of opinion.
But it is so typical Michael Mann and his scorched earth rhetoric, disagree with him and you are “terribly dishonest”!!!
I hope that D’Arrigo and many colleagues are starting to understand the deleterious influence of Michael Mann in a wide variety of contexts. Surely scientists should be able to debate the implications of a study without one calling another “terribly dishonest” for a difference of opinion.