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Good news and bad on climate extremes
By Bob Beale
April 8, 2009
Extreme heat is of most concern (photo: Bob Beale)
By Bob Beale
April 8, 2009
Extreme heat is of most concern (photo: Bob Beale)
The increases in temperature extremes Australia faces this century due to global climate change will not be quite as large as some have feared, according to a new study by UNSW researchers published in Geophysical Research Letters.
The team compared the climate models used by the Intergovernment
The researchers looked specifically at rare extreme events - those that occur on average once each 20 years - because heatwave conditions can dramatically affect biological, physical or human systems and are of most concern for planners and policy makers.
They found that the best-performing climate models simulated smaller rises in the temperature extremes compared with the models that performed poorly.
The study's authors caution that this is not good news: the increases in the extreme temperatures predicted by the strongest models are still extremely high and would generate heat waves much worse than the recent one that hit south-eastern Australia, they say.
The least accurate models were found to bias the average of all IPCC models towards higher temperature increases of about 3 to 5 degrees Celsius over most of the continent by the end of the century. When those weak models were removed from the average, the predicted increase was 2 to 3 C (although in some regions the increase could be smaller or greater).
Recent heatwaves - such as the recent ones in Adelaide or Melbourne - have been "phenomenally hot", notes one of the authors of the study, Professor Andy Pitman, co-director of the UNSW Climate Change Research Centre.
Professor Pitman points out that Melbourne's record maximum temperature reached 46.4 C during the heatwave and power systems failed and trains were stopped by warped rails. At Hopetoun Airport in Victoria, a new record maximum temperature for the State was recorded on 7 February at 48.8 C.
"Even with our revised projections, adding two or three degrees to 47 C days is not a prospect I think anyone would like to experience," he says. "The lower figures are not as bad as 3 to 5 C, but they're still very bad and emphasise the need to aggressively cut greenhouse gases on a global scale.
"While we have not determined if this result is common to other continents, our results were similar over temperate, sub-tropical and tropical regions so we think its likely that our results can likely be extrapolated elsewhere."
The study was authored by Sarah Perkins, Professor Pitman - both of the UNSW Climate Change Research Centre- and Dr Scott Sisson, UNSW School of Mathematics and Statistics.
Media contacts:
Professor Andy Pitman: a.pitman@unsw.e
Dr Scott Sisson: scott.sisson@un
UNSW Faculty of Science media liaison: Bob Beale 0411 705 435 bbeale@unsw.edu
