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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The gist of this is as follows:
Climate models tend to predict, due to their sensitivities, large cooling spikes due to volcanic eruptions. Apparently, the volcanic cooling estimated from tree rings is not nearly as large. Mann has put together a model which suggests that tree rings will underestimate the volcanic response.
This is all very odd, because just the other day at Lucia’s blog, I was discussing paleo reconstructions, and they were defending as representing temp because you could see volcanic cooling episodes clearly. My response was that I found it more problematic for the recons that you could see volcanic eruptions. They aren’t easy to spot in the real observational record. Mann wants to claim volcanic effects are underestimated by current recons? No way, the observations seem to indicate they over estimate.
Consider Krakatoa, the largest volcanic “spike” in terms of “forcing” in the observational record. The cooling seen in the observations? Well it’s quite difficult to tell in the monthly noise, but it doesn’t look like it’s more than about .2 degrees in the monthly (HadCruT 4). I tried to get it to show up better with a 13 month centered average, it ended up being more like .1 degrees at it’s peak. This should get lost in the noise in the reconstructions.
@Fred berple
scientific “fireworks” = a heated discussion. To an outsider it’ll be a drab conversation reaching decibel levels equivalent to an electric toothbrush.
Ms Witze has made a big blunder, because anyone who critices Michael Mann is a anti-science Mann harasser.
You see, acording to Mann, Dr. Micheal Mann is a special type of scientist. He infallible and always right and anyone who attack him must be on the pay of big oil.
Mann: “@alexwitze: D’Arrigo claim our study provides fodder for climatechange deniers terribly dishonest. It’s just the opposite…”
The political claim from DiArrigo (as paraphrased by Mann) followed by Mann’s own political counter-claim just shows us what both of them are really concerned about. If Mann were a scientist of any merit his response would have been along the lines of “I don’t care who it does or does not provide fodder for; can we please just stick to the science.” And likewise, if D’Arrigo really cared about the science, she wouldn’t have brought politics into the debate. Unless she was trying to appeal to the devil-we-know? It’s anti-science, either way.
fred berple: “What we are seeing in the long sad history of tree ring “science” is nothing more than phrenology. ”
I think you are now being mean to phrenologists to suggest their work is no better than dendrochronology..
🙂
Garret – the peer review system in the climate sciences is tainted beyond all hope. The empirical evidence is this and similar blogs.
NAP has a very interesting free paper:
http://www.nap.edu/catalog.php?record_id=12192&utm_medium=etmail&utm_source=The%20National%20Academies%20Press&utm_campaign=NAP+mail+6.14.12+-+PDF+Anniversary+(MyNAP)&utm_content=customer&utm_term=B
On Being a Scientist:
A Guide to Responsible Conduct in Research: Third Edition
Perhaps one or two people might read this article and benefit from it.
Bob
So trees are not-sensitive-enough to warming, so you have to hide the decline, and trees are not-sensitive-enough-to-cooling, so you have to amp the incline, or something.
Obviously, the trees can run rings around the dendros. Put that in your pipe and tweet it.
Marshall McLuhan would probably exhale a happy sigh @literates reduced to #twits.
David, UK says:
June 15, 2012 at 7:04 am
agreed, it’s a sad spectacle to see prominent (if not so respectable) scientists slagging it out about who might say what in politics. They are supposed to be analyzing a scientific paper, and they are debating the political “context”….
Hmph. Another drive-by trolling.
Yes Ric. There are all sort of optimal and suboptimal temps involved around enzyme processes, transportation, etc. The freeze line and the effective temp of that plants ‘anti-freeze’ tend to be at the minimum. Never seen a sample based on a woody plant that could experience non-growth years because of temperatures not rising above freezing certain years. I suspect such a micro-climate would be ‘above’ the tree line.
But if you completely defined it, it would be too long to tweet. 😉
D.J. Hawkins,
I agree with dp. Read Montford’s The Hockey Stick Illusion [available on the right sidebar] to see just how thoroughly corrupt climate pal review has become. It was written before the Climategate emails came out, which confirm what is in Montford’s book. It is truly scandalous, and Garret sounds like a clueless apologist for the relatively small clique of climate charlatans led by the dishonest Michael Mann. I don’t know what Garret gets out of it, but it’s not the truth. The truth is not in Michael Mann, who is nothing but a self-serving scoundrel. That is why he fears and loathes any public debate, preferring instead to hide out, and let useful fools run interference for his invented claims based on falsified proxies.
Climate pal review is not about science. It is about keeping the grant gravy train from being derailed by the truth: which is that nothing unusual is happening with global temperatures, or glacier growth, or global precipitation, or ice cover, or hurricanes, or sea levels, or any of the other bugaboos that are routinely shown to be fabricated climate alarmism. All of those cycles have happened before, repeatedly, and to a greater degree than at present. The fact is that over the past 150 years we have been in an extremely benign global climate, with temperatures rising only about 0.8ºC – while over the past 15,000 years global temperatures have risen and fallen by tens of degrees, on very short, decadal time scales.
The null hypothesis remains unfalsified. What is being observed now has been observed routinely in the past. There is absolutely zero real world evidence that the rise in CO2, from a tiny 0.00028 of the atmosphere, to a still tiny 0.00039, has caused any harm at all. And there is satellite evidence showing that the rise in that beneficial trace gas has caused a greening of the planet. Furthermore, the U.S. is a carbon sink, soaking up much of the world’s excess CO2, while America gets the blame for causing the “carbon” [non]problem.
All those observations are factual and testable. But you don’t see them in the pal reviewed literature, because where would the money come from if scientists honestly admitted the truth: that nothing bad or unusual is happening?
People like Michael Mann are lying for money, status, and endless jaunts to holiday venues around the globe. But they will not debate their claims, because they do not have the facts to support their assertions. What is truly hard to understand is the refusal by Mann’s cheerleaders to accept the fact that his claims consist of pseudo-science based on corrupt proxies. What do they get out of repeating Michael Mann’s provably unscientific nonsense? What is their payoff for being a useful idiot for Michael Mann?
I go over to the topix news place sometimes and read their global warming forum. Ok: me and about 15 other people argue with global warmers all the time. In this kind of propaganda war, it really helps you keep your momentum by doing mostly,
precisely what, an organization would do: find the most lethal point that you know will be there the day the big disasters start pouring down on the other side, and just go back to it, over; and over; and OVER.
See this makes the other side, very very angry and somewhat demoralized; because no matter what they say, that lethal point keeps being there: in their face: and each day’s progress is ruined when the readers come by and see you rebutted them.
For – literally MONTHS now: my stock thing has been to simply say:
“Why didn’t YOU or ANYONE you KNOW
realize the M.A.G.I.C.A.L. T.R.E.E.M.O.M.I.T.U.R.S.
AINT
REEL
HEET
SINT
SURS?
Why didn’t YOU or ANYONE you KNOW
realize about that ***LIGHT, HEAT, WATER, S.I.X.T.E.E.N. nutrient MINERALS in PROPORTION
thing?
WHY?
Becaws yew thawt that ‘tair M.A.G.I.C. HOCKEY STICK MAYuTH
wuz REEL TO.
And YEW THAWT THAY DUN CYFERD DUUMzDAY with it,
from thuH
MAGICAL TREEMOMITURs with the “600 year dataloggers” built in.”
Listen: they have been hating my guts in a big way but there’s more: If I get really torqued, I simply roll out this occasionally:
Ok I roll it out all the time. It stops them in their tracks and I mean like *snap*
“WHY didn’t you REALIZE it was a SCAM when the INFRA RED ASTRONOMY FIELD
never rolled out the PHOTOS of the SKY – 100, 50, 25, 10 years ago, and TODAY-
showing “ALL THIM MAGICAL INFER REDS wat DUN GOT TRAPT up THAIR whur thUH
Presuhdint’s jet’s HEET SINT SUR AINT NO GOOD?”
LoL. What can they say? What could they have EVER said?
Nuttn’ That’s what. A great big “…!DOH!”
Mann will soon adjust the hockey stick to indicate that the global average temperature was actually much lower than his original data indicated, which will make the current climate appear all the more overheated.
The Mann is desperate, clutching desperately to modeled data and synthetic proxies, and trying to convince everyone that trees make good thermometers if only he manipulates the data properly. He seems to be confused by his own jabber speak. Does he believe that if it reads like an academic paper, it will be accepted without question? All he has done is point out another failing of his favorite temperature proxy.
Imagine that the trees are grown in a laboratory, and you want to correlate the temperature in the lab to the rings. The first thing you must do is control for all other variables, and grow enough trees at different temperatures to have a representative sample. How did he account for all the uncontrolled variables that might be present on the side of a mountain? Doesn’t he see that as a problem? The whole idea of using trees to tell temperature strikes me as pointless. All you really know is how favorable overall conditions were for the tree.
If the climate is varying, how can a tree which lives for hundreds of years be constantly on the temperature limit? Such a concept is absurd. If the climate is changing, then the tree cannot be constantly at the limit.
It isn’t dendroCHRONOLOGY. It is dendroCLIMATOLOGY.
The former is about establishing dating, the latter about climate. Yes, the latter is a branch of the former, but they should know enough to use the correct and specific term.
Steve Garcia
Why on Earth do people use TWITter??
It’s a Tree Ring Circus, with a little mann as the Ring Master….
Remember: The Show Must Go On!
MtK
Uff dah. Just goes to show you shouldn’t comment with only 4 hours of sleep the night before. Somehow I read dp’s comment as a slam on WUWT.
“We support this conclusion with an assessment of synthetic proxy records created using the simulated temperature variations. ”
OMG, as if proxy analysis was not uncertain enough, they now start making “synthetic proxy records”
Is there not end to the hubris and stupidity that gets passed off as science in the litchuchur?
The climate change wars have degenerated to the level of cocktail party insinuations and watercooler backstabbing. Twittering enables the rest of us to understand that the first four letters describe the most enthusiastic users of the medium.