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global warming). Projected regional warmings were around 2.5°C to 3°C and
rainfall increases of up to around 60 per cent in the vicinity of major regions of
heavy rainfall, such as the inter-tropical convergence zone.
Acknowledgements
We acknowledge the modelling groups, the Program for Climate Model Diagnosis
and Intercomparison (PCMDI) and the WCRP's Working Group on Coupled
Modelling for their roles in making available the WCRP CMIP3 multi-model
dataset. Support of this dataset is provided by the Office of Science, US
Government Department of Energy.
Notes
1 Analysis of the climate models employs the probabilistic method developed by
Watterson (2008) and Watterson and Whetton (2011) and used in the most recent
national climate projections for Australia (CSIRO and BoM, 2007). Based on this
approach, a probability distribution is fitted to the projected local changes for 4°C
global warming from across the 23 climate models. This provides the 10th, 50th and
90th percentile thresholds for each case, with 90, 50 and 10 per cent (high, medium
and low) chances of exceeding these thresholds.
2 Assessment derived from a large perturbed-physics climate model ensemble.
3 Defined as mainland Australia south of 33.5°S and east of 135.5°E.
4 Based on the climate model ensemble (using the Watterson [2008] method).
5 'Least hot, wettest' combines the 10th temperature and 90th rainfall percentiles. 'Mid
case' combines the 50th percentiles for changes in temperature and rainfall. 'Hottest,
driest' combines the 90th temperature and 10th rainfall percentiles. These combina-
tions are consistent with the tendency for drier conditions to be linked with greater
warming over Australia (Watterson, 2011) and also highlight cases of greatest interest
to many affected systems (such as ecosystems and hydrology). Note that this process
ignores potentially very important seasonal differences in rainfall occurrence, but it
nevertheless should indicate sites of broadly similar annual maximum temperature
and water balance. Also note that the results presented here are for 1 4°C of global
warming relative to 1990, not the pre-industrial period, and thus represent a slight
overestimate (by around the equivalent of 0.5°C of global warming) of the 1 4°C GW
case.
6 Using CSIRO and BoM (2007), which gave projected changes in potential evapo-
ration based on the climate model archive and the method of Morton (1983).
7 Based on Hennessy et al. (2008a), who assessed changing drought occurrence in 13
climate models by examining trends in annual dry events that occurred once in 20
years in the twentieth century.
References
Braganza, K., K. Hennessy, L. Alexander and B. Trewin. 2013. Changes in extreme
weather. In Christoff, P. (ed.), Four Degrees of Climate Change: Australia in a Hot World .
Earthscan: London, ch. 3.
Christensen, J. H., B. Hewitson, A. Busuioc, A. Chen, X. Gao, I. Held, R. Jones, R.
K. Kolli, W.-T. Kwon, R. Laprise, V. Magaña Rueda, L. Mearns, C. G. Menéndez, J.
Räisänen, A. Rinke, A. Sarr and P. Whetton. 2007. Regional Climate Projections. In
 
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