Sunday 22 November 2009

CRU emails No.2: applying pressure to change results

Boy, searching the email database for "CSIRO" has been interesting. If you like trawling through long and boring emails that is.

Back in 1999, it appears that the WWF - World Wildlife Fund - wanted to use some research that the CRU had done. I don't know if they paid for it or not.

My first read of this can be summarised as follows:

  1. Barrie Pittock (ex-CSIRO) is right in with the IPCC, being retired and working part time for it. He was involved in writing all 4 IPCC reports.
  2. Barrie has a son working for the WWF
  3. Barrie is involved with a WWF staffer, who is on a CSIRO advisory committee
  4. Mike Hulme and CRU produces a paper on how rainfall patterns will change in response to climate change, and the WWF shows interest in using the results
  5. However, the results are not disastrous enough for the WWF - the confidence levels used does not show enough catastrophic floods and droughts to make an impact with the public and politicians
  6. Barrie leans on Mike to change the confidence levels so that the WWF will have some juicy disasters to promote in an upcoming pamphlet
  7. Barrie wanted Mike to change his report because if released as is, the media might have asked awkward questions, as it was not sufficiently alarmist
  8. The main impact of the change was that "this has the effect of showing precip. changes for the majority of Australia even in the B1 scenario" - presumably, before the change in the confidence level, the majority of Australia did not show changes in rainfall levels.
  9. The report is released to the media via the WWF. The media accepts it at face value, and the public are told that rainfall levels across most of Australia are going to change dramatically, leading to bigger droughts and floods - but this is not what the original report said at all.

This string of emails between Mike Hulme (Professor at CRU) and Barrie Pittock (ex-CSIRO) show that Mike was convinced to "sex up" (my words) his report for the WWF because it was not scary enough.

Barrie is the author of the well known book "Turning up the heat". It appears Barrie wrote another book back in 1985 called the Environmental Consequences of Nuclear War. I guess that gives you an idea of where he is coming from.

Dr Barrie Pittock led the Climate Impact Group in CSIRO until his retirement in 1999. He contributed to or was a lead author of all four major reports of the Intergovernmental Panel on Climate Change.

Barrie has this as the footer to his emails:

* As from 1 March 1999 I have become a CSIRO Post-Retirement Fellow. This means I do not have administrative responsibilities, and am working part-time, primarily on writing for the Intergovernmental Panel on Climate Change.

The gist of this email exchange in 1999 rests on confidence levels. Barrie is unhappy that Mike has chosen confidence levels that fail to predict the doomsday scenario that the WWF are seeking.


Peter and I did discuss it on Friday. Our main concern (although there are other more detailed ones) is your use of the 95% confidence limits of natural climatic variability as some sort of threshold for change. This is a reasonable thing to do if you are addressing the question of whether climatic change will be detectable at a "scientific level" of confidence, but that is certainly not the question I would expect WWF to want answered, nor is it the one most relevant to giving policy advice. The relevant question is "What is the best estimate of climate change, given the assumption that increasing GH gases will cause change?". The contrast between these questions, the statistical criteria they require, and thus the answers, is what I was driving at in my comment on your paper in Nature. It is a very serious difference with serious consequences for how people will interpret your advice. The results as you present them suggest that many areas will have precipitation changes (particularly) which are small compared to natural variability, and therefore it does not matter. But if the change in mean is some appreciable fraction of natural variability, say, 50%, that is a very serious matter which ought to concern policy makers, because it will have cumulative impacts, especially in regard to large changes in the frequency and magnitude of extremes (floods and droughts). Surely you understand that! - refer to the standard diagrams of the impact on extremes of shifting a normal distribution by one standard deviation.

What you are doing is using a strict Type I error criterion when others (WWF?) might think a Type II error criterion is more suitable (the Precautionary Principle), and reasonable people (like me of course!?) think a criterion in between which measures risk of serious impacts is
what is needed for policymakers.

I would be very concerned if the material comes out under WWF auspices in a way that can be interpreted as saying that "even a greenie group like WWF" thinks large areas of the world will have negligible climate change. But that is where your 95% confidence limit leads.

Mike replies:

The point behind all this is to emphasise that precip. changes are less well-defined than temp. changes *and* that we should be thinking of adaptation to *present* levels of precip. variability, rather than getting hung up on the problems of predicting future precip. levels. This pedagogic thinking is hard to communicate in a short WWF brochure.

Your concern about my message is well taken, however, and I intend to remove any reference to 95% confidence levels, to re-word the text to indicate that we are plotting precip. changes only 'where they are large relative to natural variability', and to reduce my threshold to the 1 sigma level of HadCM2 control variability (e.g. this has the effect of showing precip. changes for the majority of Australia even in the B1 scenario).

But I do not intend to abandon the concept. I think it important - even for Greenie groups - to present sober assessments of magnitudes of change. Thus making it clear that future changes in T are better defined that future changes in P, and also to point out that future emissions (and therefore climate change) may be as low as the B1 scenario (is B1 climate change negligible? I almost think so), whilst also being possibly as high as A2 is I think very important.

The alternative is to think that such a more subtle presentation is too sophisticated for WWF. But I think (hope) not.

My take on this is that Mike bowed to pressure from "the group" (whoever that is) to change his confidence levels in order to create a more enticing graphic for the WWF pamphlet. As he notes, the subtlety of his research is hard to communicate in a short brochure, which is why Green groups simplify complex issues and then shout that simple message as loudly as possible.

Barrie replies, explaining his close connection to the WWF:

I should perhaps explain my delicate position in all this. As a retired CSIRO person I have somewhat more independence than before, and perhaps a reduced sense of vested interest in CSIRO, but I am still closely in touch and supportive of what CAR is doing. Also, I have a son who is now a leading staff member of WWF in Australia and who is naturally well informed on climate change issues. Moreover, Michael Rae, who is their local climate change staffer, is a member of the CSIRO sector advisory committee (along with some industry people as well) and well known to me. So I anticipated questions from WWF Australia, and from the media later when the scenarios are released, regarding the scenarios. I did not want to be in the position of feeling the need to seriously question in public their presentation or interpretation. You have allayed my fears on that score, so that is great.

Mike emails his assistant and tells her to change the graphics to suit the WWF needs. His comments are:

Given what has happened and your role in producing these plots, you may interested in the exchanges I have had with Barrie Pittock - it illustrates nicely the nuances of presenting climate scenarios in different Fora. Read these three emails in reverse order.




And then there is this:

From: Adam Markham
Subject: WWF Australia
Date: Thu, 29 Jul 1999 09:43:09 -0400

Hi Mike,

I'm sure you will get some comments direct from Mike Rae in WWF Australia, but I wanted to pass on the gist of what they've said to me so far.

They are worried that this may present a slightly more conservative approach to the risks than they are hearing from CSIRO. In particular, they would like to see the section on variability and extreme events beefed up if possible. They regard an increased likelihood of even 50% of drought or extreme weather as a significant risk. Drought is also a particularly importnat issue for Australia, as are tropical storms.

I guess the bottom line is that if they are going to go with a big public splash on this they need something that will get good support from CSIRO scientists (who will certainly be asked to comment by the press). One paper they referred me to, which you probably know well is: "The Question of Significance" by Barrie in Nature Vol 397, 25 Feb 1999, p 657

Let me know what you think. Adam

Like I said earlier - they wanted to sex up the reports to make a bigger public splash. Bugger the actual science. Tailor the story to suit the audience - in this case, Australians.

1 comment:

kc said...

After a cursory look at your other posts on this, I'm going to read through them one at a time, more slowly. Your analysis makes it much more coherent to me. Thank you.