Comments on CSIRO Chief's erroneous claims of 30-40% reductions in SW WA rainfall in last 25 years.

On 25 November the influential ABC TV 7.30 Report ran a segment on the drought featuring interviews with leading climate scientists.

Dr Graeme Pearman Chief of the CSIRO Division of Atmospheric Research made much during the interview of the CSIRO position, "...that, because of global warming, that drought conditions will be more common in the future than they are now."

Later in the interview when talking about SW WA rainfall Dr. Pearman stated "The rainfall in the south-west, the extreme south-west, has been reduced by 30 per cent to 40 per cent, on average, for the last 25 years."

Let us look at a map of the distribution of rainfall reductions in the years 1976-2001, compared to the years 1925-1975. This map below has been produced by the Indian Ocean Climate Initiative (IOCI) of which the CSIRO is a partner and  Dr. Pearman is a Research Member.

This map Fig 2
just published by the  IOCI in a report "Climate variability and change in south west Western Australia" shows clearly that there can be no areas of significance in SW WA where rainfall records display the reductions announced by Dr Pearman on the 7.30 Report.    For Dr. Pearman to be correct we would expect contours on the Fig 2 map to extend to 70 and 60 per cent of 1925-1975 levels.
A quick note here to say that while Dr. Pearman's 7.30 Report statement can only be interpreted as meaning total annual rainfall, not any seasonal fraction, the map above is measuring the reduction in wet season, May to October rain which is probably more marked in percentage terms than reductions in annual rainfall.  Dr. Pearman's statement is way out of touch with the facts whether he meant to say May to October rainfall or if he really was referring to annual rainfall.

So, Dr. Pearman's statements display an amazing detachment from the reality of  everyday climate statistics for someone who has been preaching and pontificating at every opportunity about how hot and dry we will be in decades to come.  When the man clearly can not recall salient facts about  rainfall data in SW WA, how on earth can he be taken seriously when trying to convince us about the distant future.   Looks like a classic case of, " not bother me with facts, my mind is made up."

Posted 5 December 2002

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