Friday
Apr122013
by 
Bishop Hill
Bishop Hill Mann and Nucitelli on climate sensitivity
Apr 12, 2013 Climate: sensitivity Apologies for the lack of posts today. I was rushing to write something this morning (see below), before rushing out for the day.
For me, the news of the day was this: Michael Mann and Dana Nucitelli wrote a piece on climate sensitivity for ABC of Australia. I wrote a response in the Spectator Coffee House blog.
Somewhat related, at Climate Etc, Nic Lewis has a long detailed look at the data of the Forest 2006 climate sensitivity study.
Reader Comments (25)
An excellent response Andrew to a typical piece of Mann-drivel.
The drivel goes like this: "you say sensitivity is low, with some new studies. Well, why don't you look at these other, older studies that are in opposition...." ;-)
If heat has gone into the oceans, without raising surface temperatures, that is accepting that sensitivity is low.
I find it hard to take *any* discussions of so-called climate sensitivity seriously.
@Martin A
totally agree...it is one of those equations that can have infinite solutions depending on what you measure at what timescale. It is not exactly an SI measure.
Mann and Nuccitelli
One of which who wrote an Amazon one star book review of Andrew's Hockey Stick Illusion and had to confess he had not actually read it when presented with evidence of a post previously written by himself.
And the other one who wrote a whole book to try to counter Andrew's HSI without actually saying so.
It is interesting that a scientist of Mann's prestige is now publishing with someone as null as Dana...does that tell you that Mann has been pushed from the bus?
A year or two ago I argued at skeptical science that the pictures of the "independent sources of information" are not independent. Climate models are the only source of relatively high sensitivity estimates, other sources like paleo data yield 1 to 6C where the high end is laughable in that it requires attributing most warming to CO2 rather than albedo decreases, dust reduction, weather regime changes, etc. I show the missing piece of Nuticelli's diagram here:
http://shpud.com/weather/main.php?g2_itemId=66
The counter argument to my argument was basically that the figure 3b (the blocks) was independent of 3a (the curves) and didn't need to be shown. Obviously the curve shapes come from models since only models can produce such faux "probability distributions". Another problem is that the diagram pretends to corroborate short and long term sensitivity, for example models of with volcanic aerosols and glacial to interglacial transitions. Models overestimate the climate response to volcanic forcings ( e.g. http://wattsupwiththat.com/2012/09/10/volcanic-corroboration/ ) and they cannot determine how much heat goes "missing" in the deep ocean, a long term consequence with no current practical consequence.
@diogenes "does that tell you that Mann has been pushed from the bus?"
If climate science is ever to regain its integrity, climate scientists will have to push Mann (and Gleick, and a few others) actually under the bus, not just from it.
The climate sensitivity of 3C +/- 1.5C with a likely sensitivity of 3C first appeared in the Charney Report in July 1979. It's not clear (to me at least) how they got to that figure. Having said that it's doesn't seem clear to Charney as he mentions two other sensitivities in the report. If we examine the evidence however they would have been using extremely basic computer models, and indeed, computers in 1979, when a gigabyte of memory would have occupied a whole block of a university and processor speeds were MHz, so it has to be a crude attempt at estimating the effects of all the different feedbacks, positive and negative, to come up with a value of 3C +/- 1.5C
So here we are 34 years later, when its possible to get a 64 gigabytes of memory onto a device smaller than a cigarette packet, and computers routinely run at many GHz and having spent $100bn+ on climate research and we find that the sensitivity range is 2C - 4.5C with a likely sensitivity of 3C.
What was it Muhammed Ali said? "If you still think the same way at 50 as you did at 20 you've wasted 30 years of your life."
@geronimo: the key claim justifying the climate sensitivity of CO2 is that you get evidence of it in the OLR spectrum, the 'dip' in the 15 micron CO2 band. It is presented here: PhysTodayRT2011.pdf
[The dip] “represents energy that would have escaped to space were it not for the opacity of CO2”
This mechanism is justified by the comparison of the base of the dip with the S-B black body curve and claiming emission is from 220 °K therefore CO2 has raised the emission height to get that lower temperature. Unfortunately, these people have failed to understand that CO2 is strongly self-absorbing so not only is the measured amplitude half the BB level, there is no absorptivity increase as you increase concentration beyond ~200 ppmV.
220 °K means real 260 °K emission temperature, about what you get at 50 km in the stratosphere where local thermodynamic equilibrium ceases (hence the central peak in the band). They got it wrong.
"If we examine the evidence however they would have been using extremely basic computer models, and indeed, computers in 1979, when a gigabyte of memory would have occupied a whole block of a university and processor speeds were MHz"
For reference, I ported the GCM I was using in 1994 from the Cray at Rutherford lab to the Convex in the University of London mainly to get the benefit of the 512MB to 1GB of memory increase.
It is interesting how little has changed in the conclusions since the Charney report. It is quite a good read in at least it sounds like it is being scientific. I like this from the summary, surely a proper update is needed now the grandchildren are starting to appear.
"In order to address this question in its entirety, one would have to peer into the world of our grandchildren, the world of the twenty-first century."
"...The claim was primarily supported by a single as-yet unpublished article by a group in Norway, which attempts to use instrumental temperature evidence available back through the late 19th century to estimate the climate sensitivity. ...... they find that by including just an additional decade of data .... the estimate falls by nearly half...."
Odd that Michael Mann complains about this. He started the Great Climate Scare with a single paper whose detailed data remained unpublished for many years using a mix of instrumental and tree-ring data. And It was shown that if you left out one tree from his paper, his graph immediately became meaningless. So he has a lot of form in providing mathematical half-truths.
By now, Mann's paper has been comprehensively debunked and he has been unable to rescue it - not for want of trying. Having seen the effects of such criticism on his own work, he is obviously trying the same arguments on his opponents. However, I suspect that their maths is better than his was...
Does the fact that Michael Mann has had to team up with Dana Nucitelli mean that he is being shunned by the rest of the Team, who are embarassed at being associated with someone who displays such complete ****?
We've been seeing a lot of the "we owe it to our children and to our children's children" stuff lately. How about we sort the present out first?
Apr 12, 2013 at 11:34 PM | Diogenes.
I sincerely hope that it was an electric powered bus that they threw Mann under...
I work on the buses.
If a volunteer driver is needed to perform this essential public duty, I am at your service.
I will try to find an old clapped out one (those recently retired from the T33 service would be perfect) to use so that we don't harm a useful new vehicle.
Yes - do you remember when "climate science" was such a specialised subject that the opinions of "mere amateurs" like Steve McIntyre, Watts & Bish were beneath contempt.
Now completely unqualified, self promoted activists like Nuccitelli (Bish - I think it's two "c"s) and Cook get their names on articles (and even published papers) with the "great & the good" - presumably because real scientists have sniffed the breeze and are keeping their heads down.
Nuccitelli cunningly describes himself as an "environmental scientist" - he actually works for a environmental consultancy group who do US government work on stuff like water engineering and site clean up.
Here's a 2008 bio from the days when he was just an activist:-
.Dana Nuccitelli aka 'scooter-boy' ... will be delivering your pizza tonight, sir. Please have the right change as he's not permitted to handle money ... and please, no tipping.
geronimo (5:40 AM)
"The climate sensitivity of 3C +/- 1.5C with a likely sensitivity of 3C first appeared in the Charney Report in July 1979. It's not clear (to me at least) how they got to that figure."
I thought the Charney report was admirably clear on that point:
It's a bit of the wet-finger-in-the-wind technique, but as you say, they had only a few primitive models to go by. To me, the fact that the Charney report got pretty close in 1979 is a remarkable result showing that they -- modelers and Charney -- focused on the most salient effects. That the sensitivity of modern models hasn't seemed to improve, is a shame. Forster et al. 2013 says the 90% range of ECS in CMIP5 models [AR5] is 3.22°C +/- 1.32°C. [And this set of models is similar to those of CMIP3 [AR4], whose mean has over-predicted recent warming.]
Isn't it a bit strange to refer to someone with a degree in astrophysics and a masters in physics as "completely unqualified"?
OK, you don't like the guy, but seriously?
Please, can we stop with the personal comments? I have as little regard for the objectivity of Dana's writings at SkS, but let's concentrate on what he writes and not his personal characteristics. A degree in physics from Berkeley is not to be looked down upon, also. Yes, he's an amateur in climate science, but so are we all, except a very few commenters. It doesn't disqualify him from making assessments.
harold, lots of sceptics have degrees as well. They don't go around waving them in front of everyone else's faces, do they? How does having a degree in astrophysics make you a 'scientist'?
Nic Lewis - 'financier'
Matt Ridley - 'failed banker'
Roy Spencer - creationist
Nuccitelli - scientist
Yeah, right.
Why are these two scientists unable to rise above argument by misrepresentation?
Shub -
"lots of sceptics have degrees as well." Yes, I suspect that quite a few of those who comment here have academic credentials equal to or in excess of Nuccitelli's. But more importantly, those credentials are not required to make intelligent observations about topics such as energy policy, vested interests, or the agreement of model predictions and measurements.
If Nuccitelli is currently employed in a scientific position, he's entitled to call himself a scientist if he wants. It's up to the reader to decide whether to give any credence to his writings.
And yes, the derogation of skeptic commenters, as in your examples, by those defending the "consensus" is not admirable. Why would anyone want to mirror that behaviour?
NUCCITELLI and MANN have plenty of links to the articles in support of their arguments, but not to the original Economist article. Must be an error, as I am sure would not want to attempt to win an argument by ignoring any possible counter-arguments. So that an editor at ABC can make the corrections, the Economist article is here and the leader here.
Has anyone else noticed that ABC has taken down the comments on the Mann Nuccitelli article? It looks as though the comments were not exactly going the way ABC wanted. Most were critical of Mann and Nuccitelli's spin.