Today I received a reply from CSIRO regarding the Drought Exceptional Circumstances Report. I was very pleased that Mr Hennessy expresses an interest in providing the data needed to check the results, and will refrain from further comment until I get the data and analyze it.
From: David Stockwell
Sent: Monday, 7 July 2008 1:56 PM
Subject: Exceptional circumstances report supplementary information
Could you please direct this enquiry to the appropriate person.
I am interested in obtaining the supplementary information for the Exceptional Circumstances Report. In particular, I would like to obtain the results for the individual 13 models used in the summary tables 4, 7, and 9. If possible, I would like information on the tests that were conducted to determine the statistical significance of projected increases in % area of temperature, rainfall and soil moisture, supporting such statements as follows:
“A new report is predicting a dramatic loss of soil moisture, increased evaporation and reduced ground water levels across much of Australia’s farming regions, as temperatures begin to rise exponentially.”
I also note from the BOM site that the supplementary information is not due to be released until 31 July. Would you please let me know why the detailed information necessary for checking the report has not been released in conjunction with the main report.
The response was as follows:
Thanks for your enquiry.
Firstly, the report (with typos fixed) and Supplementary Information are available at http://www.bom.gov.au/climate/droughtec/ . I have asked DAFF to provide a link to the Supplementary Information.
Secondly, some of the media reports have misinterpreted the findings of the report. We have little control over this.
Thirdly, the Terms of Reference (Appendix 1) state that â€œit 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.
However, in response to your request, we have undertaken further work. I can confirm that for the mean scenarios:
- the % area for exceptionally hot years is significant at the 5% level for all regions
- the return period for exceptionally hot years is significant at the 5% level for all regions
- the % area for exceptionally low rainfall years is significant at the 5% level in the SW, SW WA and Vic&Tas regions
- the return period for exceptionally low rainfall years are significant at the 5% level in the SW, SW WA and Vic&Tas regions
- the % area for exceptionally low soil moisture years is significant at the 5% level in the SW, SW WA, NSW and Vic&Tas regions
- the return period for exceptionally low soil moisture years cannot be calculated since the â€œpastâ€ sample has only 1 value (for the period 1957-2006)
I have also attached sample plots of individual model results for % area with exceptionally low rainfall years in SW WA. Weâ€™d rather not plot any more regions or variables until we know whether this type of plot is of any use to you.
Principal Research Scientist
Climate Change Research Group
Centre for Australian Weather and Climate Research
A partnership between CSIRO (Marine and Atmospheric Research) and the Bureau of Meteorology
PB1 Aspendale Victoria