Business Day: THE deteriorating state of world financial markets does not materially affect Treasury’s economic model for reducing Australia’s greenhouse gas emissions, according to the man behind the model. Treasury’s macro-economic group executive director, David Gruen, also played down the cost of cutting emissions, saying the resulting 0.1% decline in gross national product by 2050 was five times less than the effect on the economy of the ageing of the population. Dr Gruen moved to …