One of the better aspects of the Australian Garnaut Review of the economics of climate change is the straightforward language in which it is written. That particularly applies to the introductory and concluding chapters (PDF), the latter of which is entitled “Fateful choices.” Perhaps the finest passages in the whole work concern how we ought to respond to the uncertainty that remains in projecting future climatic change as a function of human emissions:
[T]he Review accepts the views of mainstream science ‘on a balance of probabilities’. That formulation allows the possibility that the views on climate change of the IPCC and the learned academies in all of the main countries of scientific achievement are wrong.
There is a chance that they are wrong. Just a chance. But to heed instead the views of the minority of genuine sceptics in the relevant scientific communities would be to hide from reality. It would be imprudent beyond the normal limits of human irrationality…
The mitigation process can be cut short, with due notice to those who have committed their capital to a new economy of low emissions, if at any time the international community comes to the view that new scientific knowledge establishes that the concerns of 2008 were erroneous to the extent that mitigation judgments based on them have become obsolete.
In this case, Australia would have paid 2 per cent of GNP as insurance against what would otherwise have been a high risk of immense damage. It would be a high price, but one that was reasonable on the basis of the evidence available at the time when decisions had to be made.
The consequences of inaction now are not similarly reversible. The arithmetic of Chapter 3 (PDF) about the new patterns of global growth takes away the time we may once have thought we had for experiment, talk, and leisurely decision making. It tells us that business as usual is taking us quickly towards what the science tells us are high risks of highly disruptive climate change…
On a balance of probabilities, the failure of our generation would lead to
consequences that would haunt humanity until the end of time.
The report concludes that an international agreement is vital. It needs to include a global goal for the concentration of carbon dioxide at the moment of stabilization (550 parts per million, perhaps, for an initial agreement – refined to 450 ppm in a subsequent iteration). The agreement needs to incorporate equity concerns, especially through the principle of contraction and convergence, and national commitments must add up to the global target.
It must be very much hoped that the UNFCCC Conference of Parties in Copenhagen next year will at least begin the process towards those outcomes. Barack Obama’s apparent seriousness about making climate change a priority is cause for optimism. If the US, China, India, Japan, and Europe can reach an accord, it seems likely that enough others will be drawn in to make the thing really work.