The Federal Government has released a report into the link between drought and climate change, which it says will trigger major review of drought policy. The report is by the Bureau of Meteorology and the CSIRO and is the first of three commissioned by the Government.
The report warns that extreme conditions previously thought to occur once in every 20 to 25 years, could become as frequent as every one or two years. Prime Minister Kevin Rudd has told ABC1's Insiders the report paints a very disturbing picture about the future of droughts in Australia. "When it comes to exceptional or extreme drought, exceptionally high temperatures, the historical assumption that this occurred once every 20 years has now been revised down to between every one and two years," he said. "Exceptional circumstances drought conditions ... will occur twice as often and with twice the area of droughted parts of Australia included. "Now this is a serious revision of the impact of climate change on drought."
Recently, however, an examination of the assumptions behind the CSIRO report has been done by Dr David Stockwell, a modelling expert. Excerpt:
"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..
Except in the few cases noted above, the model simulations have no resemblance to patterns of observed droughtedness in the last century. We conclude the models have failed internal validation and no further testing is warranted."
In other words, those wonderful "models" the CSIRO relied on don't give an accurate picture of what has actually happened in the past. And if they can't get the past right, how can we expect them to get the future right?
A recent article in the Hydrological Sciences Journal also found that climate models had no validity in portraying the climate of regional areas (such as Australia). The one thing we can test about such models is how accurate they are in "back-predicting" the past -- and they fail utterly. The journal Abstract:
On the credibility of climate predictions
By D. Koutsoyiannis et al.
Geographically distributed predictions of future climate, obtained through climate models, are widely used in hydrology and many other disciplines, typically without assessing their reliability. Here we compare the output of various models to temperature and precipitation observations from eight stations with long (over 100 years) records from around the globe. The results show that models perform poorly, even at a climatic (30-year) scale. Thus local model projections cannot be credible, whereas a common argument that models can perform better at larger spatial scales is unsupported.
Source (H/T Agmates)
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