Garnaut and the science of climate change


Professor Ross Garnaut's draft review of climate change policy options for the Australian government was released on July 4, with climate change minister Penny Wong due to release a green paper canvassing policy options on July 16. Garnaut's report looks at the "costs" and "benefits" of mitigating drastic climate change through a carbon polluting trading scheme. It suggests tax cuts and "welfare reform" to compensate low-income households, which will be hit hard by energy price rises.

While the report was released too close to publication to give Green Left Weekly time prepare an adequate response (see the next issue for further discussion), the draft report summary and Garnaut's public statements in recent months give a clear idea of the draft's shortcomings. The new document, though acknowledging that "without early and strong action, some time before 2020 we will realise we have indelibly surrendered to forces that have moved beyond our control", does not make action proposals that address the real urgency of the climate dilemma.

There are no proposals for the massive public investment in renewable energy power generation and public transport that need to be made now. The proposals trading off economic costs against environmental threats through a carbon emissions trading scheme to be set up in 2010 will be irrelevant outright dangerous.

The entire exercise, in fact, is fated to serve mainly as a blind for corporate irresponsibility and government foot-dragging.

These are harsh judgments, but they are compelled by the widening gulf that separates the review's terms of reference from rapidly advancing climate science.

In a public lecture at the Australian National University on June 5, Garnaut stated: "The Review's terms of reference require it to analyse the degree of Australian mitigation effort that would be necessary to support a global agreement to hold [atmospheric] greenhouse gas concentrations to 550 ppm [parts per million], and separately to 450 ppm."

The figures here refer to "carbon dioxide equivalent", a combined value for various greenhouse gases in the atmosphere. In April 2007, when Garnaut was engaged by the then Labor opposition to prepare his review, even the figure of 450 ppm was beginning to be regarded by climate scientists as involving definite risks.

Since then, the news has got worse. In April this year, renowned US climate scientist James Hansen, head of NASA's Goddard Institute for Space Studies, released the findings of a study conducted with eight highly regarded international collaborators. Unlike most earlier essays in climate change prediction, Hansen's study was substantially based not on computer modelling, but on hard evidence from the paleoclimatic record — that is, material evidence remaining from tens of millions of years of changing atmospheric composition and varying temperatures.

Hansen's evidence indicates that present-day "climate sensitivity" — defined as the eventual global warming that can be expected from a doubling of atmospheric carbon dioxide over pre-industrial levels — is much greater than earlier work suggested.

Until Hansen's study, the figure usually cited for climate sensitivity was about 3°C. Hansen and his team conclude that this figure doesn't fit the climate dynamics of the past 34 million years, since today's major icecaps began to form. For a world with ice, Hansen's calculations indicate, the appropriate figure is around 6°C.

Hansen's doubled figure for climate sensitivity fits well with the unnerving tendency of observed climate change to run far ahead of scientists' predictions. What will it now do to Garnaut's review?

Not to be too blunt, Hansen's revelations turn a great deal of what Garnaut proposes into nonsense — and dangerous nonsense at that.

If climate sensitivity is indeed twice what was earlier believed — and Hansen's work here is the best indicator we have — then the target of 550 ppm of carbon dioxide equivalent translates into a likely global temperature rise approaching 6°C. For scientists' predictions about the effects of such a rise, readers can turn to Mark Lynas's 2007 book Six Degrees. The human species, Lynas indicates, would be lucky to avoid extinction. The chance of any kind of advanced civilisation surviving would be dim indeed.

Expressed as parts per million of carbon dioxide equivalent, the current figure for greenhouse gases in the atmosphere is a little over 460; for carbon dioxide alone, the figure is 387. Hansen concludes that in order to preserve a planet like the one to which life on Earth is adapted, atmospheric carbon dioxide will have to be cut to no more than 350 ppm, and perhaps considerably less.

Within a few decades, net greenhouse emissions will have to fall to near zero. The cost will be burdensome, and the task will have to be a concerted world priority. But the price of failure is unspeakable.

In the light of Hansen's careful science, Garnaut's key concerns appear quite disconnected from reality. That is, how to reduce greenhouse gases without hurting the economy. But refusing to pay the price of halting climate change means there will be no economy, except perhaps for the most primitive.

How to construct a workable carbon trading system? You can only trade emissions when the system contains a definite slack, when there are significant emissions you can allow to proceed. That stage was passed at least a decade ago. Now, there is nothing left to trade with. You have to plant the trees, and shut down the coal-fired power plants.

Few Australians have heard of James Hansen, but most of us know about Ross Garnaut. In months to come, the "climate change" headlines of daily newspapers will be full of Garnaut's proposals and perspectives. In the case of many readers, the distraction will be successful. Countering climate change will be seen exclusively in terms of fine-tuning the market model.

Meanwhile, the coal companies will carry on expanding their exports. And the Rudd government will continue its empty talk and chase an undeserved public approval — a model of phoney climate activism.