My evaluation of the validity of the modelling in the CSIRO Drought Exceptional Circumstances Report, and the R code used to produce it, is available below. A pdf and invitation for review is posted on WikiChecks.
In a statistical re-analysis of the data from the Drought Exceptional Circumstances Report, all climate models failed standard internal validation tests for regional droughted area in Australia over the last century. The most worrying failure was that simulations showed increases in droughted area over the last century in all regions, while the observed trends in drought decreased in five of the seven regions identified in the CSIRO/Bureau of Meteorology report. Therefore there is no credible basis for the claims of increasing frequency of Exceptional Circumstances declarations made in the report. These results are consistent with other studies finding lack of adequate validation in global warming effects modeling, and lack of skill of climate models at the regional scale.
Directions for Doing Analysis Offline
1. Make sure you have a copy of R, and the library gdata (for reading xls files)
2. Save this script to your working directory.
3. Download the following data online from http://www.bom.gov.au/climate/droughtec:
Historical Data > Time series of percentage area below the 5th percentile
Projections Data > Time series of percentage area below the 5th percentile
4. Save the files at a directory ../data/csiro and untar
tar xvf *
5. Run the script with the following: