Squeezing information from regional climate change projections - results from a synthesis of CMIP5 results for south-east Queensland, Australia

We present a synthesis of CMIP5 model results for projected rainfall changes for a single region (south-east Queensland, Australia) and note that, as was evident in CMIP3 results, the multi-model mean projected changes for the late 21st century are not statistically significant for any season nor annually. Taking account of the number of statistically significant changes to mean rainfall, we find some evidence favouring a decrease in both spring and annual rainfall, but this is not compelling. In almost all cases the most frequent result is for no significant change. However, if we consider the number of results where there is a statistically significant change in the distributions of rainfall amounts, there appears to be slightly more information available for risk assessment studies. These numbers suggest an increase in the frequency of both wet and dry events during summer and spring, and a shift towards more frequent dry events during winter. There is no evidence for any significant changes to the distributions for either autumn or annually. The findings suggest that, in one respect, multi-model rainfall projections may contain more information than is evident from syntheses which focus on changes to the means and that, for some regions where changes in the frequency of wet and dry seasons/years have known impacts, the model projections may be more valuable than previously thought.