Geophys. Res. Lett. 36, L06710 (2009)

Credit: BLOODSTONE/ISTOCKPHOTO.COM

When it comes to simulating temperatures in specific regions, some global climate models are more skilful than others. For Australia, new research finds, those that reproduce past regional temperatures best also consistently project smaller increases in extreme temperatures in the future, relative to other models.

Sarah Perkins and colleagues at the University of New South Wales in Sydney tested nine global climate models for their skill in replicating past climate, by comparing their simulations of temperature extremes in Australia from 1981 to 2000 with observations. For each region of the continent, they picked the three models that performed best. This select group of models shows that if greenhouse gas emissions continue to grow, the very hottest days of 2081–2100 — the kind of scorchers that occur once every 20 years on average — will be 2 °C hotter than a century beforehand almost everywhere, and 5–7 °C hotter in the hardest-hit places. But if all models are included, peak temperature over most of the continent shoots up to 3–5 °C higher than a century ago.

The authors conclude that focusing on the best-performing models for a given region significantly changes climate projections. Since Australia includes both temperate and tropical climates, this effect could be widespread around the globe.