Doomed Planet

“The evidence is not there”

On Wednesday, May 25, 2GB’s Alan Jones interviewed climate change scientist Professor David Karoly and discussed various comments Karoly had made on climate matters.[i]

Three issues in particular stood out, not so much for their information as the manner in which Karoly slid around the questions or made comments that were incorrect or incomplete. Karoly is frequently cited as an authority on the subject and has advised the Australian government on climate change.

The first of the three issues dealt with Karoly’s comments in 2003 about the Australian drought at that time:

JONES:  In 2003 why did you say quote this drought has had a more severe impact than any other drought since at least 1950? This is the first drought in Australia where the impact of human-induced global warming can be clearly observed. Now the Bureau of Meteorology’s national rainfall data contradicts your statement. There is no overall change in trend, just a continuing cycle of drought and flood and these are similar to the past, no worse, no better. Why did you say that? To frighten people?

KAROLY:  So I said that because there is clear evidence that the temperatures in 2003 in Australia were hotter than in any other drought period in Australia. So the temperatures were hotter and most of your listeners would know that when it’s hot – you know, on a hot day – you get more evaporation. Water on your path, the water on your gardens dries out. So the reason I said that that drought [in 2003] was worse was because of the hotter temperatures. … When it’s hotter that has a greater impact in a umm than when it’s cooler in a dry period and so your listeners would know absolutely when it’s hotter the droughts and the conditions are worse. That’s why I said it. Because there is clear evidence that in that drought in 2003, up to that period, the hotter temperatures made the conditions in the drought worse. Your listeners know that when it’s hot and it’s dry the conditions are worse than when it’s dry and it’s cool.

This is not the first occasion that Karoly has said or implied that higher temperatures drive drought. This has raised the ire of hydrologist Professor Stewart Franks more than once, and I am aware that Franks has contacted Karoly in an attempt to stop him repeating this fallacy.

According to Franks, the situation is the reverse – drought drives higher temperatures. The reasoning is simple. A drought means that there is little or no moisture on or just under the surface of the ground and very little available moisture held in vegetation. In this situation heat energy from solar radiation will not be used to evaporate that moisture and take it high into the atmosphere, as would be the case if plenty of moisture was available, but all of the heat will be used to warm the ground surface, which in turn will warm the air. 

It’s not only Franks who make such statements. In their analysis of the European heatwave of 2003, Black et al[ii] mention that the ground surface was abnormally dry, and state in their conclusions "…the temperature increase at the surface was exacerbated by the inability of latent heat fluxes to transfer heat upwards due to the lack of moisture availability." The IPCC’s 2007 report [iii] commented "An exacerbating factor for the temperature extremes was the lack of precipitation in many parts of western and central Europe, leading to much-reduced soil moisture and surface evaporation and evapotranspiration, and thus to a strong positive feedback effect (Beniston and Diaz, 2004)".

Franks has, quite understandably, questioned the meteorological competence of Karoly on this matter.

The second disturbing matter in the interview is how Karoly handles a question that relates directly to his work for the 2007 IPCC Fourth Assessment Report (4AR). Late in the conversation Jones comments on my analysis of the review process for the IPCC 4AR of 2007[iv]:

JONES: Well the UN’s data, the UN’s own data, shows only five of its reviewers, only five, this is the UN’s own data, endorsed the claim that carbon dioxide caused global warming and there’s doubt that they were even scientists. And these are your people, the reviewers. You were the review editor. It’s your chapter.

KAROLY: Alan. You’re wrong and John McLean is wrong. The number that he’s referring to, I don’t know where they come from but there were more than 2000 review comments from more than 100 different authors [sic!] providing independent peer-review of chapter nine. And those data and the authors and the review comments they are available from the IPCC.

It is difficult to imagine that Karoly is not well aware of my document seeing how it has been widely cited, even on the floor of the US senate, and it relates directly to his work for the IPCC. More than that, I know for a fact, because I was sent a copy of emails sent to Karoly by Malcolm Roberts. In his e-mails Roberts explicitly drew Karoly’s attention to the document title and provided the URL so that he might access it over the Internet. In checking with Roberts he advises that Karoly was further advised of my numerous presentations of UN IPCC data on chapter 9 by e-mail and by Registered Post with Delivery Confirmation, apparently sent to Karoly as part of Roberts’ complaint to the University of Melbourne over various statements by Karoly.

The document to which Jones and Roberts referred was based on information supplied by the IPCC, to wit the reviewers’ comments, so it can hardly be disputed. In it I state very clearly how the data was processed and how I arrived at the conclusion that only five reviewers expressed explicit support, and I quote the comments that I regard as providing that endorsement.

It is true that more than 100 reviewers (not authors!) made over 2000 review comments – actually 117 and 2603 respectively – but Karoly is talking about total numbers, not about the number of reviewers who expressed support, and that’s a very different matter.

He has avoided answering the direct question by claiming ignorance and giving an answer to a very different question. 

The third and most important issue in the Jones and Karoly interview relates to the question of empirical evidence in the 9th chapter of IPCC 4AR. Jones begins by asking Karoly for empirical evidence, that is, evidence obtained by observation and experimentation.

JONES:  Is there any empirical evidence proving human production of carbon dioxide – as distinct from nature’s production – caused global warming? Is there? In these reports? Yes or No?


JONES: Now where would I find that in chapter 9 [of the 2007 IPCC report] – that’s your chapter.

KAROLY: Sure. You would find that evidence in the peer-reviewed scientific studies and in the data …

Note Karoly’s response here. He doesn’t say that empirical evidence can be found anywhere within the chapter itself but says that it’s in the cited papers and the data.

The consequences of an absence of empirical evidence are staggering. If it’s not in the chapter then it can hardly be in the IPCC Summary for Policy-makers, and if it is not in that document then it looks like government representatives approved a document that contained no empirical justification for its claims.

Jones’ interview with Karoly goes on:

JONES: But where in chapter 9?


JONES:  Where in chapter 9? Where can I open chapter 9, because I looked at it, where if I open chapter 9 is that evidence? Where is it?

KAROLY: It’s … I can’t tell you the page number because I don’t ...

JONES:  No, no. It’s not there. It’s not there.

KAROLY:  What. No, Alan.

JONES:  It’s not there. You, the chapter review editor. It’s not there! That’s why you can’t tell me the page number. The evidence is not there.

KAROLY: That’s not true Alan.

JONES:  Well I’ve got scientists on stand-by who are going to listen to all this so your reputation’s on the line when you say that. I’m telling you chapter 9 is your chapter. You were in fact the chapter’s review editor and you can’t tell me where the evidence is.

KAROLY:  Yeah, I can. Would you like me to tell you where the evidence is? The evidence is in the spatial patterns and the time variations of temperature changes in the observations …

JONES:  Whoa, whoa, whoa. Chapter nine, chapter nine, David, is the chapter. It was originally chapter 12 in the 2001 report. In the 2007 report you were the review editor of this chapter on the direction … on the detection of climate change. It’s now called "Understanding and attributing climate change". Now to understand climate change you need to know what evidence there was for all of this. In chapter 9 it’s not there.

And now look closely at what Karoly claims is evidence – an "evaluation", a simulation of "what we’d expect".

KAROLY: No Alan it is there. So would you like me to tell you which figure in particular in chapter 9 shows that evidence? It looks at the patterns of climate variations over the last 50 and the last 100 years and what it does is it makes an evaluation or an assessment. It talks about how climate has changed compared with what we’d expect from greenhouse gas variations, it also looks at other factors. Factors like change in sunlight from the sun, changes in the effect of volcanoes, natural variations like El Nino’s, natural variations like the Pacific Decadal Oscillation and what it shows, what it clearly shows, is that the patterns of change are outside the range of natural variability, aren’t due to changes in sunlight from the sun and we can see that because sunlight from the sun would cause more warming in the daytime when the sun’s really important but we’ve actually observed more warming at night. We’ve seen changes in the temperatures in the lower atmosphere and the upper atmosphere which clearly show that the changes are due to the increases in greenhouse gases and aren’t due to natural variability and aren’t due to other factors. And we’ve …

JONES: Chapter nine, chapter nine, doesn’t contain any of that detail. Can I go on?

KAROLY: Yes, it does.

Karoly is correct in that the information that he mentions is contained within the chapter, but Jones requested empirical evidence and Karoly has failed to provide it.

In his response Karoly does not tell the full story. He incorrectly claims that temperatures since 1950 were outside the range of natural variability when its variation and trend were almost identical to that of 1918-43; the magnitude of the temperature is of little significance because the accuracy of the IPCC temperature is highly suspect, many factors related to its gathering and processing being very inconsistent over the last 150 years.

He fails to mention urban heat island effects that might account for warmer night-time temperatures, and he implies that only one interpretation is possible for the change in tropospheric temperatures. He also omits the fact that the observed temperatures higher in the stratosphere are not in agreement with climate models that presume that carbon dioxide has a significant influence. Further, the climate models on which several inferences are based are, according to the IPC, flawed and invalidated. He also fails to state that since 1977 the Southern Oscillation Index, the proxy measure of the El Nino-Southern Oscillation, has been largely on the El Nino side of the scale and that warmer weather is therefore to be expected.

None of this is surprising to me. Malcolm Roberts stated during our discussion that Karoly has failed to satisfactorily respond to a request for specific, scientifically measured real-world evidence that would support his claims, and that the request was first raised almost 18 months ago.

My overall impression from Karoly’s comments are firstly that he is lacking in fundamental understanding of an important meteorological concept; secondly that if his statements about my document are correct he is curiously incurious about some trenchant criticism of the IPCC review process in which he played a vital part; and thirdly that when asking about empirical evidence he made a rapid shift to "derived" material of dubious origin and then was highly selective about the issues that he mentioned.

I see Karoly as less of an impartial and knowledgeable scientist and more of an advocate who carefully selects his data in order to present a certain view and seemingly has no empirical evidence to support his fundamental claim. That’s a very disquieting thought given his involvement with the IPCC and his role of government advisor.


While completing this article I was advised of Professor Karoly’s appearance before a parliamentary committee in 2000:

Reference: Kyoto Protocol,


Senator LUDWIG: Do you have a view about whether Australia should ratify the Kyoto Protocol?

Prof. KAROLY: I have a strong personal opinion that Australia should sign for two reasons: first of all, to provide a first step to reducing global greenhouse gas emissions, and as an indicator of commitment to mitigating – reducing – global climate change. Developing countries are unlikely to believe that developed countries have any commitment to this until they sign on to the Kyoto Protocol and make some first steps. Again, this is a personal opinion not to do with my scientific expertise.

It would therefore seem that eleven years ago, in 2000, Karoly was already expressing an opinion "not to do with [his] scientific expertise", and he was advocating certain action. "Impartial advisor" doesn’t exactly seem to be the appropriate description.


[i] Jones’ interview with Karoly can be heard at ) or downloaded (for playing via a utility with time displays) at 

[ii] Black, E., M. Blackburn, G. Harrison, B. Hoskins and J., Methven (2004), Factors Contributing to the Summer 2003 European Heatwave Weather Aug. 2004 vol59. No. 8 

[iii] IPCC 4AR (2007), section 3.8.4 (Box 3.6) 

[iv] McLean (2007) – An Analysis of the Review of the IPCC 4AR WG I Report, see 

[v] Commonwealth of Australia, Joint Standing Committee on Treaties, Reference: Kyoto Protocol, (2000), Proof Committee Hansard, 

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