An effective response to climate change must take shape and be in place in the next few years, the federal government's top climate change adviser says.
Professor Ross Garnaut's 600-page draft report on climate change, of which the make-up of an emissions trading scheme (ETS) is a major focus, was released today.
Speaking at the report's launch in Canberra, Prof Garnaut said climate change was a "diabolical" policy problem.
"While an effective response to the challenge would play out over the many decades, it must take shape and be in place over the next few years," he said.
"Without early and strong action, some time before 2020 we will realise we have indelibly surrendered to forces that have moved beyond our control."
Prof Garnaut said climate change was the hardest policy problem in living memory.
"Climate change presents a new kind of challenge," he said.
"It is uncertain in its form and extent, rather than drawn in clear lines.
"It is insidious, rather than directly confrontational.
"It is long term, rather than immediate in both its impacts and its remedies."
Remedies will require global co-operation of unprecedented complexity and dimension, he said.
"We have much to contribute and much to lose as we face the diabolical policy challenge of climate change," Prof Garnaut said.
Prof Garnaut said the increases in concentration of greenhouse gases in the atmosphere over the past two centuries, especially in the last half century, generated the climate change now being experienced.
"This is the result of economic activity in the countries including ourselves that are now rich," he said.
"The rapid increase in concentrations that are expected over the next several decades and which makes action to avert dangerous climate change urgent is primarily the result of activities in the developing countries that are becoming rich."
Prof Garnaut said it was not desirable nor remotely feasible to lower the climate change risk by substantially slowing the rise in living standards anywhere, least of all in the developing countries.
That approach would not be accepted by Australians or by the developing countries, he said.
The draft report also presents the early results of the review's economic modelling if no action is taken, Prof Garnaut said.
"On the middle-of-the-road impacts as defined by the science, these impacts which we subjected to modelling cut 4.8 per cent GDP by the end of the century, over $400 billion dollars in today's purchasing power, $400 million dollars per annum over, 5.4 per cent from consumption and 7.8 per cent from real wages.
"The modelling can cover only some of the benefits of climate change mitigation."
Prof Garnaut said his recommendations on emissions targets and carbon pricing would be contained in a supplementary report to be released at the end of August, as well as in the final report to be released at the end of September.
He said the supplementary report would contain the results of the joint modelling that the Garnaut Review was undertaking with the federal treasury department.
"It's that supplementary draft report that will answer many of the questions... about the review's recommendations on targets and trajectories, and the implications of that on likely carbon pricing.
"When we have that, we can talk in more detail about the structural impact on the Australian economy.
"I've avoided speculation on these matters and it would not be helpful to speculate now."
Prof Garnaut said Australia had a bigger interest in addressing climate change than any other developed nations because it was a hot and dry country.
"And small variations in temperature and rainfall have a much bigger impact here than on other developed countries," he said.
Unlike other developed countries, Australia's neighbours were mainly fragile developing countries, he said.
"The problems of our neighbours would inevitably become our problems," he said.
Furthermore, the structure of Australia's economy means its terms of trade will be damaged more by climate change than those of any other developed country, he said.
Prof Garnaut said climate change held a serious threat for Australian tourist industry icons.
"With unmitigated climate change, on the basis of the mainstream science, we won't have much, if any, of the Great Barrier Reef, of Kakadu, of a number of our great environmental assets that are important attractions for international tourists.
"We've studied those impacts."