The Garnaut report demonstrates how our obsession with economic growth is so powerful that we are unwilling to contemplate sacrificing a tiny amount of consumption now to sharply reduce the risk of climate catastrophe.

The report presents modelling results on the economic implications of stabilising atmospheric concentrations at 450 parts per million (ppm) of carbon dioxide equivalent (CO2-e) versus allowing them to rise to 550 ppm. (The pre-industrial level was 280 ppm of CO2 and we have now reached 387 ppm.)

The 450 ppm target will be accompanied by warming of about 2°C by the end of the century while 550 ppm is likely to see warming of 3°C.

Climate scientists believe that the difference between the two is huge with 550 ppm dramatically increasing the likelihood of catastrophes and runaway climate change – such as an irreversible melting of the Greenland ice sheet resulting in sea-level rise of 7 metres. That would rule out any chance of returning the atmosphere to a safe level for thousands of years.

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Yet Garnaut’s recommendation that the Government aim for a 10% reduction over 2000 levels is based on the belief that stabilizing at 450 ppm is politically infeasible and we must reluctantly accept a 550 ppm world.

How much will pursuing the 550 ppm target cost us in terms of lost income? Garnaut says it will shave a little more than 0.1 per cent from GNP growth through to 2050. This means that instead of growing annually at, say, 2.5 per cent if we do nothing, GNP per person would grow at “only” 2.4 per cent if we aim at 550 ppm. Aiming at 450 ppm would cost only fractionally more.

The welfare cost can best be understood as follows. With an annual real growth rate of 2.5 per cent per person, then with no carbon abatement Australia’s GNP will double by 2040. If from 2012 we aim for the 550 target our GNP will not double until 2042, i.e. we will have to wait an additional two years. And, according to Garnaut’s modelling, if we aim for the much safer target of 450, we will have to wait another six months.

To even ask whether this trade-off is worthwhile is bizarre. To conclude that it is not, which it seems the Rudd Government will decide, is madness. Our rationality has been disabled by our growth fetishism.

The economic impact of pursuing a target of 450 ppm rather than 550 ppm is so small that it will be exceeded by the normal statistical error involved in measuring GNP growth. Yet it seems that this amount is so large that it renders the safe option politically infeasible.

Does anyone believe that Australians would be less happy if they had to wait an extra six months before they became twice as rich? The absurdity of the situation exposes a form of paralysis in our political system where we and our leaders have become imprisoned by a world view that has elevated economic growth to a sublime level.

Garnaut himself expresses the trade-off in simple terms. He describes three types of benefits of cutting emissions: insurance against breaching catastrophic tipping points; protection of non-market environmental qualities not reflected in markets (such as the loss of the Barrier Reef); and, avoiding large costs in the next century. He then asks:

Is it worth paying over the course of the century less than 1 per cent of GNP for the non-market benefits, insurance value and the enhancing value beyond the 21st century of the 450 strategy?

He says this is a matter of judgment. Anyone who has to give more than a moment’s thought to this choice must be deluded. No sane person could entertain the possibility that there is more than one answer to this question.