http://www.canberratimes.com.au/news/opinion/editorial/general/act-now-on-climate-change-before-it-is-too-late/2243799.aspx?storypage=0

We need to start taking climate change seriously and working out measures to address it.

Over the past 18 months the quality of the political dialogue on climate change in Australia has spiralled downwards, following the removal of Malcolm Turnbull as leader of the Coalition in December 2009, and Kevin Rudd's repudiation of his own policy on responding to climate change in April 2010.

Increasing numbers of Australians have simply tuned out of this discussion and, if asked, will either confess confusion on the specific questions put to them, or repeat whatever punch line the leader of the political party they support has uttered most recently.

Efforts by experts on the science and economics of global warming to stimulate a rational discussion with the general public have been repeatedly drowned out by the frantic cacophony emanating from politicians, elements of the mainstream media, and commercial vested interest groups who seem more interested in frightening us, rather than informing us.

On current form, Australians will continue to face unanswered questions on the significance of the climate issue and on their real options to deal with it. Most people will not know how effectively the carbon price soon to be put before the Parliament will reduce emissions; a good many MPs will be similarly ignorant. If we were able to calculate the specific risks and timing associated with the various catastrophic environmental events that unabated climate change will bring, then we could reasonably estimate the costs of adaptation to specific environmental changes as global warming proceeds, and of mitigation of their consequences.

But the truth is, we cant calculate these things. What we face is not a neatly organised set of predictable risks, but a timeframe uncertainty for which, by definition, we cannot calculate specific probabilities. Ross Garnaut, in a 2011 update of his 2008 review of the climate change issue, reminds us that we must nevertheless understand as much as we can about the likelihood of possible outcomes - something we are clearly not achieving in the current climate change debate.

While we face uncertainty about what will happen when, however, we can be very certain indeed that the various major and potentially disastrous environmental events the scientists predict will arrive on our doorsteps, eventually. We can also be certain that if we do little or nothing to reduce emissions now, these events will come sooner, and their impact upon us will be more intense, than would be the case where significant reduction of greenhouse gas emissions had been in train for some time.

Climate-change deniers - well- practised at taking scientific observations and economic arguments on the climate issue out of context and then inverting their true meaning - will seize upon the uncertainty argument as indicating that, since the scientists have admitted they dont know exactly what will happen when, we should take no action now. This is the exact reverse of the logical conclusion, which is that the only scientifically and economically defensible strategy under this uncertainty is to invest in measures that will most cost-effectively reduce emissions, as soon as possible and to the maximum extent we can afford.

That is the only lever we have at present to mitigate the pace and intensity of unwelcome environmental changes. There has been a vigorous global debate occurring in international economic circles about how to make choices on this issue. The more traditional economic view is argued by the American economists William Nordhaus, Robert Mendelsohn and others. Among other points, Nordhaus invokes the conventional intergenerational equity argument: Future generations are almost certainly going to be richer, and therefore more able to invest in adaptation, mitigation of consequences and so on than we are now.

So why should we be investing heavily now in emissions reductions for their benefit? On the other side of this debate, Nicholas Stern draws more heavily upon the implications of the science on climate change to argue that, if we fail to implement significant emissions reductions very soon, the likely magnitude of the costs of catastrophic change those future generations will face will in fact be far beyond their means - financial and technical - to address.

In effect, Stern turns the intergenerational equity argument on its head, and ventures an estimate of what those future generations could face: " ... if we dont act, the overall costs and risks of climate change will be equivalent to losing up to 5per cent of global GDP each year, now and forever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20per cent of GDP or more.. "

The well-known sceptical environmentalist, Bjorn Lomborg, who has in the past criticised proponents of immediate and significant action on climate change, has recently changed his mind, suggesting that large sums need to be invested now, to avert catastrophic damage to the environment. Interestingly, in the context of the present argument in Australia, he suggests a tax on carbon emissions would be an essential element in financing the measures he proposes.

By all means we should also be prepared to adapt to specific climate change events as they happen, but to invest only in adaptation - and only then - would be suicidal: it would be like attempting to appease a well-armed and menacing enemy without making any accompanying deterrent investment in defence, in the expectation that this strategy will somehow reduce the risk of an attack. Applying adaptation strategies to specific changes may in any case turn out to be no easier than taking a general precautionary approach on emissions reduction from the beginning.

What if a particular environmental change we see happening, and for which we are implementing adaptive measures to combat, turns out to be less urgent than a far worse one we didnt see coming? It will be of little comfort then to reflect on how much easier it would all be had we invested in emissions reduction 20 or 30 years earlier.

The discussion we should be having in Australia is on the subject of the counterfactual; what is likely to become of us, and our children and grandchildren, if we continue to do little or nothing about climate change? How much will we need to invest - and when - to get to a solution that, as a country, we can live with (in both the economic and environmental senses)?

We can choose to make ourselves relevant in the international debate on climate change by taking effective action to reduce our emissions, or to render ourselves irrelevant by sitting under our tree waiting to see what happens. We are a small economy; we need to be ahead of the curve: If we are not, and large economies do begin to scale up their efforts on emission reduction, we can be sure they will not volunteer to subsidise our recalcitrance; our terms of trade will take a major turn for the worse, possibly even before the worst environmental costs of our inaction arrive. Is this really what we want?

*  Jim Douglas has worked with the World Bank, United Nations agencies and international environmental organisations on forests and natural resources, and is now a consultant on rainforests and forest carbon. His book on international forest issues was published by Springer in October 2010.