The interim report of the Garnaut Review on climate change shows how much thinking has changed in the year since the Prime Minister’s Task Force on climate change, led by Peter Shergold, examined the same issue.

In part, of course, this reflects the change in government. The Shergold report was tied to the Howard government’s rejectionist view on Kyoto, and spent a fair bit of time on spurious defences of positions that were obviously untenable at the time. This part of the report attracted a fair bit of attention, and was rightly derided.

But there was a serious component of the report, consisting of an attempt to balance economic and environmental risks. On the one hand, the report accepted the need for emission targets to manage the risk of dangerous climate change. On the other hand, the report was much concerned with the risk of economic damage if the cost of mitigation turned out to be high. As a result, it recommended both a leisurely start to emissions trading, delaying this until 2012, and an elaborate system of escape clauses designed to operate if the price of emissions rose too high.

As Garnaut’s interim report shows, the balance of risks has changed radically. Indeed, the thinking in the Shergold report, much influenced by US-based policy debates in the period immediately after Kyoto, was already out of date when the taskforce began its work.

Massive economic growth in China and India, at rates far higher than anyone anticipated when the Kyoto agreement was signed in 1997, have produced growth in emissions at or above the highest “business as usual” projections of the IPCC. At the same time, the news from climate scientists has mostly been bad. The evidence in the Fourth Assessment Report killed off any remaining hopes that the problem of human-caused climate change would turn out to be spurious or significantly overstated.

At this point, the risk of moving too fast on climate change is non-existent. As Garnaut shows, even moving fast, it is going to be very difficult to divert the global economy from a path leading to ever-rising CO2 levels, and increases in global temperature far beyond anything our species (or most species currently in existence) has ever experienced. The consequences of such a path are hard to predict in detail, but highly likely to be disastrous.

Where to from here? At a global level, nothing substantial will happen until the departure of the Bush Administration in January 2009. The rest of the developed world, including Australia, needs to press the incoming administration for a rapid and unconditional commitment to cut US emissions, followed by immediate negotiations with China and other developing countries to achieve an agreement that will deliver a halt to global emissions growth by 2020, followed by a substantial decline.

To say this will be a challenging task is an understatement. Of course, everything would be dramatically easier if the US and Australia had ratified Kyoto, instead of rejecting it after the election of the Bush Administration in 2001. Those who supported this course have been utterly discredited by the course of events. They will, no doubt, continue to advocate delay and indecision, but they should be left to jeer from the sidelines while others get on with the job.

John Quiggin is an ARC Federation Fellow in Economics and Political Science at the University of Queensland. His blog is at www.johnquiggin.com.