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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It just goes to show that you need to keep your Witze about you 😉
(Sorry, really sorry…)
Botanists have been saying climatologists were cranks fro years.
This has all the hallmarks of a small mann snit, headed for a tiff… or even a full blown huff!
“..Promises fireworks at poster session.” Oh Goody! I love fire works, what with the 4th of July coming up and all!
For the purposes of “climate science”, tree ring width means whatever Michael Mann wants/needs it to mean.
It’s dendro AND it’s a model. Indisputable then.
Am so glad I don’t live in Michael Mann’s world, surrounded by evil enemies lurking everywhere and forever misrepresented. No wonder he doesn’t accept debate or even dialogue.
I still don’t think Dr. Mann has a basic handle on Leibigs Law.
He doesn’t believe that Leibig’s Law should apply to his work — he certainly doesn’t believe that the FOIA applies. Besides, the only handle he’s concerned with is on his hockey stick.
I don’t think historic records support anything special about 1259. There was a famine in England, but it started in 1257, and was most likely due to bad government, not weather events.
I think the most likely explanation here is that “volcanic forcing” isn’t as simple as modelers want it to be…
Twitter? Really? Why would anyone pay any attention to the kind of people who snipe at each other on Twitter. Grow up all of you.
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.
braddles says:
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.
It’s the logical extension of post-modern science.
Sorry for using “logical” and “post-modern science” in the same sentence…
“I still don’t think Dr. Mann has a basic handle on Leibigs Law” – you refer to Liebig’s Law? Or am I missing some finer point??
REPLY: Misspelling fixed, thanks
I do not understand the NEED to “Tweet”. I do not understand how so many otherwise media-savvy persons can so comprehensively beclown themselves whilst “Tweeting”.
Why does this happen with such an exponential increase in self-beclownments? Not only that, but a permanent trail of one’s idiocy will last the human equivalent of “forever”.
Stupid is as stupid does…….
Bill Tuttle says:
Besides, the only handle he’s concerned with is on his hockey stick.
——-
Rats, I So want to take that to its’ natural conclusion…!
Revenge of the dendros?
Liebig’s Law of the Minimum is inaccurate; unlimited nutrients and sunshine will not produce a cornfield with infinite yield, e.g.
Here’s my improvement:
Brian’s Barrier: when one limiting factor is removed, there’s another.
Tweets are twiffic if you want to tersely tweak or twit, otherwise twivial.
Now there is Liebig’s Law, which might be in this case be transposed to the Law of the Big Lie, courtesy of Hitler, which then immediately terminates the discussion to comply with Godwin’s Law.
At least, no lawyers had to be paid.
Science has been reduced to soap opera status. “Tweeting” back and forth? How “manly” is that? Now that I think about it, how “manly” is the “he said, she said” exercise in which we are currently engaged? Think I’ll go chop some wood or, as Willis is inclined to say, “Pound some nails”.
This extensive use of twitter garbage just substantiates the assumption that Mann is not able to defend his positions in a profound scientific discourse.
What is the difference between Mann and his tree rings and an old lady and her tea leaves?
Answer: Not much…
140 characters will barely cover a snit and Twitter is totally inadequate for a decent rant or diatribe. I’ll wait for the paper to come out.
@Hyperthermania says: June 14, 2012 at 11:45 pm
Hey! That was a great way to start off the thread. Nicely done.
For some one who in his own words didn’t want the hockey stick to become the “be all of climate science/ipcc”, Mann is sure defending it and the methodology behind it?
While Mann and the rest of the gang are concentrating on the tiny smears on the dial of the solar system’s clockwork, there is little hope of understanding of climate, geo or solar oscillations. Current crop of scientists is letting down humankind by failing to follow in footsteps of great minds of the past centuries.
Espen said;
“I don’t think historic records support anything special about 1259. There was a famine in England, but it started in 1257, and was most likely due to bad government, not weather events.
I think the most likely explanation here is that “volcanic forcing” isn’t as simple as modelers want it to be”
I agree with you. Sorry for the length of this post but it is highy relevant to the topic; I had this same conversation a couple of weeks ago in another place with, amongst others, R Gates who used to post regularly here;
As it happens I am writing a article on the period from around 1200 to link up with my study which reconstructed CET back to 1538. I am especially interested in its impact locally and on the nearby uplands of Dartmoor.
. In consequence I have been looking in the archives of the medieval Exeter Cathedral, The Met office and Devon records office and been examining original scrolls dating back to the 13th Century. Consequently what folows is based on actual contemporary observations. Its unedited so hope it makes some sort of narrative sense;
—– —— Exchange started as follows——–
“Having now spent some time looking at evidence on the ground and written documentation in a variety of places I would look askance at science, as recently evolved in the form of ice cores and marine cores, in relation to this statement by the very eminent Jean Grove, an LIA scholar at Cambridge University (who died several years ago) and wrote;
“… marine cores taken off the southeast coast of Greenland showed warm stable conditions between 10th and 13th century followed by cold conditions beginning about 1270 and culminating probably about 1370 and a brief interruption 1370 to 1470 did not involve reversion to the relative stability and warmth of the MWP.”
I can see no empirical evidence for this downturn in 1270, indeed it seemed to contain some of the warmest years in our record. There are very many pieces in the climate jigsaw and I doubt anyone has found them all or knows how to assemble the whole.
tonyb
R. Gates | May 31, 2012 at 7:35 pm | Reply
Tony,
You said:
“I can see no empirical evidence for this downturn in 1270…”
_____
Of course I would hope you are kidding. There were a series of very large volcanic eruptions around the time of 1250-1300. The cooling affect from the release of those volcanic aerosols would be something for you to consider as potential “empirical” evidence. Ice Core data clearly shows these eruptions as occurring. But I assume you knew all this…see:
http://www.bbc.co.uk/news/science-environment-16797075
But of course, changes in solar uv output also played role in the LIA, most notably in the later periods. But early on, it seems volcanic aerosols might well have kicked the whole party off to a cool start.
climatereason | June 1, 2012 at 1:18 pm | Reply
R Gates
Of course I knew that. The written records shows for example the extreme cold caused by Icelandic eruption in the 1700′s but not ones in the period I referenced. That is not to say they didn’t happen, but written evidence to date does not show it. Reliable written evidence trumps ice cores.
tonyb
Steven Mosher | June 1, 2012 at 1:34 pm |
Funny. how do you calibrate a written record? how do you determine it is ‘reliable’ when reliable means “captures the temperature accurately” faced with a ice core that showed an eruption ( global of course and of the the right size ) and a written record that failed to record cooling, I’d take the physical evidence over the record of humans. face with a contradiction between these two ( an ice core that indicated cooling and a written record that recorded “warmer” ) I’d still take the ice core record.
Louise | June 1, 2012 at 1:49 pm |
“Reliable written evidence trumps ice cores.”
Translation: “anecdote trumps data”
ceteris non paribus | June 1, 2012 at 2:06 pm |
”
Reliable written evidence trumps ice cores.
”Card-playing metaphors do not entail that two types of evidence equals a dilemma.
climatereason | June 2, 2012 at 3:51 am |
Mosh
I suggest you read A F van Engelen/J Buisman/F Unsen of the Royal Met Office de Bilt who describe how you convert non instrunental information by putting them into 11 categories. (see History and Climate’ edited by Briffa/Jones/Ogilvie and Davies)
We have numerous records and are always searching for more, and these can be converted into reasonably accurate temperatures when they can be categorised. My ‘ The long slow thaw’ estimates are pretty close to those from De Bilt as I used this method of classification- despite what you think its not a ‘finger in the air.’
Records I researched from the Medieval Exeter Cathedral included these
1697 Charity payment to poor in severe weather
1702 and 1705 storm damage to church roof
1703 trees blown down in Cathedral Close by storm –December
1740 January ‘£23 to be given to poor in consideration of the severity of the season.’
1783 ‘Extra poor relief in extreme cold’ (due to Iceland volcano?)
I would take stuff written down by people who were there at the time rather than cores which may reflect an event but not its real world effect
Tonyb
R. Gates | June 2, 2012 at 9:45 am |
Tony,
I’m just not sure where you are actually coming from on this. You wondered about the cause of the cooling in the time frame around 1270-1300– cooling which you admitted to having occurred– and when I pointed out the very solid evidence of a series of large volcanic eruptions in this time frame as documented by ice core data, you suggest “observations trump data”. What observations are you referring to? The Vikings were experiencing increasingly foul weather in their Greenland colonies in this same time period– the same time period that the ice cores in Greenland show large volcanic eruptions were cooling the globe.
climatereason | June 2, 2012 at 10:45 am |
R Gates
No, please read my post, I didn’t say there was cooling around 1270-1300.It was the eminent Jean Grove who said it.
I said I couldn’t find any written evidence to support this (in the area I am talking about) in fact there is continued evidence of habitation on the High moors around here right through this period, and the Cathedral records have this to say;
‘The winter period was defined as the beginning of November to the end of the 11th or 12th weeks of the Christmas term-so winter lasted up to 20 weeks (note subsequent change of calendar) During this period (1279 to 1353) ‘the work force was much reduced in number on account of the weather, (in the winter) though work does not seem to have ever altogether ceased on this account.’
Just because there were signs in a core of a volcanic event around 1270 doesn’t mean this had a real world impact. However, I need to do much more research before I would disagree with someone like Jean Grove.
Louise said (and I assume that you and mosh would agree;
“Translation; anecdote trumps data”
However if the written record(s) were good and the data unsubstantiated, which would you go for? ‘Data’ because it is deemed to be scientific? Ideally both need to corroborate each other
tonyb
manacker | June 3, 2012 at 8:24 am |
steven, tony b and louise
Today’s (reconstructed) “ice core data” is recorded by human beings.
Past (historical) climate data was recorded by human beings.
If the historical data include crop records, etc., they are “harder data” than the ice core stuff.
To write historical data off as “anecdotal” (and hence inferior in quality) would be asinine. (But I’m sure that’s not what anyone is doing here.)
Max
gbaikie | June 2, 2012 at 11:20 am | Reply
“Ice cores from both the Arctic and Antarctic record a massive volcanic eruption in around AD 1258. The inter-hemispheric transport of ash and sulphate aerosol suggests a low-latitude explosive eruption, but the volcano responsible is not
known. This is remarkable given estimates of the magnitude of the event, which range up to 5 × 10^14–2 × 10^15 kg”
http://onlinelibrary.wiley.com/doi/10.1002/joc.891/pdf
So this unknown eruption was bigger than Tambora.:
Wiki: “With an estimated ejecta volume of 160 km3 (38 cu mi), Tambora’s 1815 outburst was the largest volcanic eruption in recorded history.”
160 km3 or say 320 trillion kg- 3.2 x 10^14 kg.
So unknown eruption is seemingly much bigger than Tambora.
Both these scales of eruption utterly dwarf the ones in more modern times.
Mount Pinatubo[1991]: 1 X 10^13 and Krakatoa[1883] : 4 x10^13
So around AD 1258 an eruption as much as 200 times more ejecta
Pinatubo, or perhaps as small as 10 times more than both of them combined.
R. Gates | June 2, 2012 at 2:04 pm |
Though there was a very large one around 1258, it wasn’t the only one as Ice core data show several lessor ones, but still larger than Pinatubo.
climatereason | June 2, 2012 at 3:18 pm |
R Gates
uncertainty in the 1258 record
http://www.wired.com/wiredscience/2012/02/the-mysterious-missing-eruption-of-1258-a-d/
tonyb
climatereason | June 2, 2012 at 3:36 pm |
gbaikie
the paper says it could have been a small eruption that was sulfur rich. The evidence for the severe cold seems to come from tree ring reconstructions.
tonyb
——– End of exchanges——