Tuesday, May 08, 2007

Update on Climate Change

Right this is going to take a little bit of time and effort, but here goes. I have asked a friend who knows a lot more than I do about this stuff for some thoughts in response to Declan's comments below.

He referred me to a report produced by Paul Hamer a PhD student at the University of Bristol which made claims regarding the truth/accuracy of the Channel 4 programme 'The Great Global Warming Scandal".

His main points are these, and these are the responses I have.

1) The use of outdated versions of past climate temperature reconstructions, and the failure to mention newer examples of this type of work.

Temperature reconstructions. Quibble/obfuscation. The key line is the one where someone said "We have to get rid of the Medieval Warm period." As that was the stated aim of the paleoclimatologists, you can't trust the more modern reconstructions. Indeed, they have been shown to have considerable drawbacks. For instance, the modern tree ring proxies do not show the rise in temperature everybody thinks has happened in the last thirty years. This might mean that after a certain temperature, tree rings aren't a good proxy for temperature. The IPCC has just admitted (buried in its report) that no consensus exists on this point. The graphs this guy uses are based primarily on tree rings and some other proxies that also have problems with them. See http://www.climateaudit.org/if you really want to go snow blind.

2) The allegation that because CO2 lags temperature in the ice cores, CO2 has played no role in changing climate over the last few hundred thousand years.

Ice cores. Quibble. As the note suggests, the theory about temperature lag is just a theory and it doesn't really detract from the main point - global warming does happen naturally and can precede CO2 output by some considerable time. CO2 is not the only driver of climate and may even be a minor one. Once you've established that, you must examine other possible "forcings" in depth, and as this IPCC figure shows, we haven't done that:

Until everything in that end column says "High," we're just arresting usual suspects by going after CO2. The suspects may be guilty, of course, but we owe it to science as well as to the economy to fully understand the systems.

3) Claiming that volcanoes emit more CO2 than human industrial activity.

Volcanoes. Error. I believe Durkin has admitted this.
4) Insinuating that because man’s contribution to global CO2 emissions is small, it is insignificant and not the cause of rising CO2 concentrations

Man-made emissions. I think this is an error. Durkin et al glossed over the strong evidence that man is responsible for most of the rise in CO2 concentrations. There are scientists who dispute this, but I think the evidence is strong enough.
5) The records of temperature used by TGGWS are both incomplete, obsolete and deliberately misleading.

Historical temperature record. Quibble. Durkin should not have cut off the data at 1980, and I think he has admitted and corrected this. The argument about the wiggliness of the lines is petty. Scientists "smooth" data all the time - there's even a smoothing in the graph he presents as the accurate one. The level of smoothness you get then depends on the size of the average you use. It's quite plausible to get a graph like the one Durkin uses. And the graph he wants us to use still shows an increase in the early part of the century just as strong as the one recently plus a definite increase from the 1940s to the late 70s. That remains a problem.
6) Claiming that the troposphere temperature records have not warmed faster than the surface records

Tropospheric Warming. It makes allegations about John Christy's research I don't think he'd agree with. (I will follow this up - Elaib)
7) Claiming that the Sun correlates well with late 20th Century warming

Solar Warming. Possibly an error. I don't think the case that it's all down to the Sun is particualrly strong, so I felt this was the weakest part of TGGWS. On the other hand, I don't think this summary is particularly good as to the state of the knowledge. Friis-Christensen, for instance, maintains that the criticisms of his work referred to are not valid, but he hasn't published on this yet so it's difficult to say why. Here's an excerpt from Marlo Lewis' treatment of An Inconvenient Truth that presents other arguments about solar irradiance:

8) Neglecting to mention that despite the poor direct correlation between CO2 and temperature between 1940 and 1970 there are very good scientific reasons for this

The cooling period. Quibble/obfuscation. See Dick Lindzen here and this section in particular,
In order to know what to make of this exercise, one must know exactly what was done. The natural forcing consisted in volcanoes and solar variability. Prior to the Pinatubo eruption in 1991, the radiative impact of volcanoes was not well measured, and estimates vary by about a factor of 3. Solar forcing is essentially unknown. Thus, natural forcing is, in essence, adjustable. Anthropogenic forcing includes not only anthropogenic greenhouse gases, but also aerosols that act to cancel warming (in the Hadley Centre outputs, aerosols and other factors cancelled two thirds of the greenhouse forcing). Unfortunately, the properties of aerosols are largely unknown. In the present instance, therefore, aerosols constitute simply another adjustable parameter (indeed, both its magnitude and its time history are adjustable, and even its sign is in question). This was remarked upon in a recent paper in Science (Andersen, et al, 20035), wherein it was noted that the uncertainty was so great that estimating aerosol properties by tuning them to optimize agreement between models and observations (referred to as an inverse method) was probably as good as any other method, but that the use of such estimates to then test the models constituted a circular procedure. This is as strong a criticism of model procedures as is likely to be found in Science. The authors are all prominent in aerosol work. The first author is the most junior, and when it was pointed out that the article reflected negatively on model outputs, he vehemently denied any such intent. In the present example, the choice of models with relatively low sensitivity, allowed adjustments that were not so extreme.

New uncertainties are always entering the aerosol picture. Some are quite bizarre. A recent article in Science (Jaenicke, 20056) even proposed a significant role to airborn dandruff. Other articles have been suggesting that the primary impact of aerosols is actually warming (Jacobson, 20017, Chen and Penner, 20058). Of course this is the beauty of the global warming issue for many scientists. The issue deals with such small climate forcing and small temperature changes that it permits scientists to argue that everything and anything is important for climate.

In brief, the defense of the models starts by assuming the model is correct. One then attributes differences between the model behavior in the absence of external forcing, and observed changes in ‘global mean temperature’ to external forcing. Next one introduces ‘natural’ forcing and tries to obtain a ‘best fit’ to observations. If, finally, one is able to remove remaining discrepancies by introducing ‘anthropogenic’ forcing, we assert that the attribution of part of the observed change to the greenhouse component of ‘anthropogenic’ forcing must be correct.

Of course, model internal variability is not correct, and ‘anthropogenic’ forcing includes not only CO2 but also aerosols, and the latter are unknown to a factor of 10-20 (and perhaps even sign). Finally, we have little quantitative knowledge of ‘natural’ forcing so this too is adjustable. Recall that the Hadley Centre acknowledges that the “aerosols” cancelled most of the forcing from CO2.

Yet, the ‘argument’ I have just presented is the basis for all popular claims that scientists now ‘believe’ that man is responsible for much of the observed warming! It would appear that the current role of the scientist in the global warming issue is simply to defend the ‘possibility’ of ominous predictions so as to justify his ‘belief.’

9) Misrepresenting Prof. Carl Wunsch of the Department of Earth, Atmospheric and Planetary Sciences, MIT, USA.

Carl Wunsch. Quibble. Wunsch said what he said. It is valid scientific assessment. Complaining about the framing of his words is just spin in itself.
10)That the theory of man made global warming merely aims to shackle developing countries and prevent them from developing their economies.

Conspiracy by the west. Pathetic. Either CO2 is a danger or it isn't. If it's a danger, then Kyoto adds to the danger by allowing developing nations to develop. That's why all the leading enviros are currently concerned about China, India and Brazil. If Africa is to get to their stage, it'll have to start investing in power generation and transport infrastructure. If they can't do that in the most affordable way, their development is stunted. Simple as that. I recommend Marlo's chapter XX .

So it seems that somebody, who as I say knows way more than I do about the subject will accept some of the queries but not others. One could of course point the finger at Al Gore's film and make as many serious criticisms of the facts and figures there. The point is that the Government is sending one piece of unscientific rubbish out as they considered opinion, but will not allow any other point of view to be expressed. Which as I pointed out earlier is in breech of the law.

Oh yes and Aunty, your activities in the Potteries are also sailing pretty close to the same section of the Law.


Honey said...

great word that.
shall read and digest at leisure. bit annoying though that I can't read the graphics, is that a ploy?
thank you,
I'll be back.

Anonymous said...


Just to make it clear, leaving out the temperature data from the last 20 years or so is a bit more than a quibble. Quibble? That's the understatement of the year. This is the part of the temperature record which the IPCC claim is most strongly linked to human influence, this, in essence, is what the fuss is all about. Why then did Durkin not include it? Why didn't he just use the data from HAD-CRUT and NASA-GISS? By leaving out the data post 1987 he completely misrepresented the argument of the IPCC and climate scientists. It was supposed to be a science documentary, yet it includes such elementary mistakes as this. Would you really advocate for such a mistake ridden 'documentary' (polemic) to be issued to schools?

In light of the fact that you agree that the solar climate correlation is weak post 1960, what is causing climate change? This is within the context of satellite evidence showing an increase in the greenhouse effect since the 1970s:


model results which can not reproduce the 20th C climate record without the inclusion of human forcings:


and models which seem perfectly capable of predicting future climate:


And on the subject of AIT, what exactly are Stuart Dimmock's (or your) complaints with regards to the science within AIT?


Gawain Towler said...


We don't know for sure. Many people think they know, but even they admit a ten percent chance they're wrong, which is a huge margin in science. Until we fully understand the atmosphere and how it responds to things, we can't answer the question adequately, and we're a long way from that. And as Dick Lindzen demonstrates, a lot of that 90% certainty is based on circular reasoning. That said I wonder can you answer the other comments?

Oh and can I suggest that you go and have a look at the climateaudit.org and get stuck in.

On the second, (problems with AIT) I will get back to you.

Anonymous said...

Paul H,
Here are some comments on your point 7.
(a) Your two typos in the spelling of Friis-Christensen are not a good start.
(b) You ask why the data stop at 1980. If you had bothered to read any of the papers you would know the answer to this. Estimating the cycle length is done using a filter (averaging) so cannot be done up to the present.
(c) Your statement about the yellow dot being where they used 'incorrect data' is just wrong.
(d) You refer to the article by Damon and Laut ("Strange errors ..."). If you read it and check the papers referred to you will see that the only 'strange errors' are those of Damon and Laut themselves. For example D&L say that their fig 1b comes from L&FC, which it does not.

Elaib says that FC has not published a response to D&L. The story here is interesting. Laut has published 3 papers repeating the same criticisms. The first in JGR (2000) is followed by a reply by Lassen & FC. After the third one in 2004 in EOS Forum, FC wrote a response but EOS did not publish it. You can read the response

Of course there are some errors and distortions of the truth in TGGWS. But there are also errors and distortions in other films (such as An Inconvenient Truth) and in your letter.

The Aunt said...

How do you know what I did in the potteries? I'd agreed with all parties that what we did in St*ke-*n-Tr*nt stayed in St*ke-*n-Tr*nt...