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Rudd needs to revisit Murray data
(Letter, AFR, 16 July 2008)

Prime Minister Kevin Rudd supports his government's decision to start reducing CO2 emissions by drawing attention to the current Murray- Darling river situation and the CSIRO's view, based on computer modelling, of continuing water supply problems (" Murray decline underlines urgency :PM" July 15).

However, that river system recovered from similar problems in the past following good rain. Will increased temperatures since 1975, and predictions of further possible increases, also mean persistent lower rainfall and river flows?

Recent global analysis based on satellite observations does not support predictions of lower rainfall when global warming occurs and shows serious under-estimation of rainfall from computer modelling. Australian experience supports this conclusion. Below average rainfall in south-east Australia has occurred over the post-1998 period when global temperatures stopped increasing. Earlier periods of low rainfall, such as in the 1930s when the Murray system dried up, were not usually accompanied by above average global temperatures and the long federation drought predated 20th century warming. Rudd should seek up-to-date advice on this matter.

Des Moore Director, Institute for Private Enterprise, South Yarra Vic

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