Thursday, Dec 10th, 2009
CSIRO alarmist Barrie Pittock tells off Climategate scientist Mike Hulme of the University of East Anglia for not presenting material that’s scary enough for green groups:
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.
Sorry to be critical, but better now than later!…
Dr A. Barrie Pittock
Post-Retirement Fellow*, Climate Impact Group
CSIRO Atmospheric Research
Hulme agrees to help, up to a point, to hide some doubts:
My reason for introducing the idea of only showing changes in T and P that *exceed* some level of ‘natural’ variability was a pedagogic one, rather than a formal statistical one (I concede that using ‘95% confidence’ terminology in the WWF leaflet is misleading and will drop this). And the pedagogic role of this type of visual display is to bring home to people that (some, much or all of) GCM simulated changes in mean seasonal precip. for some regions do *not* amount to anything very large in relation to what may happen in the future to precip. anyway…
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.
Thanks again Barrie for forcing me to think through this again.
Pittock then explains why he’s so keen to “improve” this material – and also illustrates just how close green groups are to the CSIRO (whose climate change risk expert Penny Whetton is married to a Greens politician):
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…
Hulme then alerts another colleague to this exchange, under an interesting header, as an example of the massaging of their message to fit an audience:
From: Mike Hulme
To: Jennifer F Crossley
Subject: Re: masking of WWF maps
… it illustrates nicely the nuances of presenting climate scenarios in different Fora
Word sure had got around the green traps about how helpful the University of East Anglia was prepared to be to green campaigners. Here is an email from green entrepreneur Adam Markham to Hulme, asking for “beefed up” scares and directing him to Pittock’s more alarming scenarios, as and example of what WWF likes:
From: Adam Markham
To: [email protected]
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
(Thanks to reader Peter.)
There is an explosive admission in this exchange that needs to be drawn out and it is to do with the following comment:
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
In statistics this is important because any 1st year undergrad is told that the scientific approach for testing for significance is a 2-sigma test; ie the 95% confidence interval. Results that are significant at no more than 1-sigma significant are as good as meaningless in the sense that they are no different to sheer randomness and would be laughed all the way out of a 1st year course on stats.
This article was posted: Thursday, December 10, 2009 at 5:20 am