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12
Sep
Below my reply to the letter here from Andrew Ash, Director of the Climate Adaptation Flagship. Concerning the Drought Exceptional Circumstances Report (DECR) there was an earlier more technical draft that could have contained validation information, but was returned by the client (DAFF) because it was unsuitable for stakeholder policy work. What does that mean? The earlier report should show what/if validation was performed to determine if the models had skill at predicting drought, and what changes were made to the report to make it palatable for the policy wonks, that is, sounding more like a disaster movie.
10 Sep. 08
To:
Andrew Ash (Director, CSIRO Climate Adaptation Flagship)
Gary Foley (Acting Director, Australian Bureau of Meteorology)Dear Sirs,
Re: Request a copy of first draft of DECR
Thank you for your prompt consideration of my letter of 3 Sep. expressing my concern with the validity of key claims in the Drought Exceptional Circumstances Report (DECR).
I strongly share your sentiment “as you know we value constructive criticism as it often helps to tighten up that science, which is vital in issues which matter so much to the future of our planet.” This leads me to believe you would be amenable to providing a copy of the first (more technical) draft of the report, in order to provide constructive criticism of the validation performed on the models used in the DECR.
We also seem to be in substantial agreement on the difficulty of modelling exceptionally low rainfall years – the substance of my critique:
1. Kevin Hennessy stated as much in the CSIROpod interview of 15 Jul.
(1.20m) There’s not been a clear indication of changes in exceptionally low rainfall years, and that’s because there’s lots of variability between decades …
(1.40m)But in terms of a long term trend its not very clear in terms of exceptional low rainfall years.2. This is the basis of my claim in the previously supplied “Tests of Regional Climate Model Validity in the Drought Exceptional Circumstances Report”.
3. You do not dispute this point in your letter of 9 Sep.
However, I respectfully submit it is not the case that my critique concerns only a narrow component of the report:
1. Under the terms of reference the BoM and CSIRO were requested (DECR Appendix 1), on the basis of current knowledge of climate change science, to assess: (points 2 and 4 of 4 points):
2. Likely changes in the nature and frequency of severe rainfall deficiencies over the next 20-30 years, in comparison to severe rainfall deficiencies defined by the available instrument records. Severe rainfall deficiency is defined as an event in the lowest 5th percentile of historical records persisting for prolonged periods and over significantly sized regions.
4. The place of past exceptional climatic events in the context of the likely frequency and severity of future climatic events.
2. Projections of exceptionally low rainfall using models constitute roughly one third of the substance of the report, along with temperature and soil moisture.
3. The dictionary definition of drought is: a shortage of rainfall. If my concerns are as narrow as to not affect the overall report, then I would respectfully suggest the report is misnamed, the word “Drought” should be dropped and replaced with “Temperature Extreme Circumstances”, or something similar. This would be consistent with the summary of the findings at the CSIROpod interview site, which only mentions exceptionally hot years, and omits claims of exceptionally low rainfall.
4. The claims at issue were quoted by the Prime Minister, the client DAFF, and in the media.
I submit that in a report whose terms of reference were to determine “likely changes in the nature and frequency of severe rainfall deficiencies over the next 20-30 years”, my critique of a major part of the summary regarding the likelihood of exceptionally low rainfall does address the main thrust of the report.
Kevin Hennessy in an email of 11 Jul. (excerpt below) mentioned the existence of a draft of their report with a great deal more technical information.
Thirdly, the Terms of Reference (Appendix 1) state that “it will be presented in a form that will enable it to be used in future drought policy discussions, including stakeholder consultationâ€. Our first draft of the report was considered too technical by the client (DAFF), since the target audience is for lay-people, so we had to spend considerable time simplifying the language, diagrams and tables. Therefore, statistical tests and results from individual climate models were not presented.
Kevin indicated in an email of 25 Sep. that:
… we are satisfied with the model evaluation done prior to publication.
I request a copy of the first draft of the DECR, commercial-in-confidence if necessary.
Sincerely,
David R.B. Stockwell PhD
10 September 2008
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