Ross Garnaut’s Supplementary Draft Report to be released on Friday will propose a carbon reduction trajectory based on a 0-15% reduction on 2000 emission levels by 2020, according to sources close to the review. The Report is based on extensive modelling by Treasury and Garnaut’s review team, which has been delayed on several occasions.

The Garnaut target has been the subject of intense speculation within the environmental movement. The possibility of Garnaut opting for a low target like 0-15% has been around for more than a week, but this week there was new speculation that the review had opted for a higher target. Yesterday the 0-15% target again emerged as the likely option.

Such a target is at the lowest end of carbon abatement trajectories and will bitterly disappoint groups pushing for the Government to pursue an aggressive carbon abatement strategy – already unlikely with a Green Paper emissions trading scheme based on extensive freebies and handouts to heavy emitters.

If adopted, a low target would also seriously reduce the chances of Green support for the Government’s emissions trading scheme if the Opposition yet again changes its position and elects not to support it. At his National Press Club speech on 9 July, Greens leader Senator Bob Brown urged a 40% reduction on 1990 levels by 2020 and said the Greens would move to amend any ETS if the target was lower.

However, the Government will be relieved that a credible source like Garnaut will have given them imprimatur to adopt a high emissions cap, at least in the early years of the scheme. A low target like 0-15% will do little to curb Australia’s emissions, but reduce the potential economic impacts on carbon-intensive industries that have been bleating about compensation for weeks. The Opposition (having finally worked out its position) strongly supports a high emissions cap until an international agreement is reached, and while the Government has said it is waiting for Garnaut on the issue, there is no doubting the political logic of a low target.

But according to Greenpeace, a 0-15% range accepts a world temperature rise of an order sufficient to inflict major damage on the Australian economy and environment. A 15% reduction would lead to stabilisation at a carbon dioxide concentration of 450 ppm and a temperature rise of at least 2-2.4 degrees, sufficient to cause significant species extinction and the loss of Australia’s Wet Tropics.

No reduction (550 ppm, and a 2.3-2.8 degree rise) would – as acknowledged by Garnaut in earlier reports — mean the loss of the Great Barrier Reef and the disappearance of 80% of Kakadu wetlands due to sea level rise, and a doubling or quadrupling of extreme fire weather events in Australia.

Garnaut’s draft report released in early July emphasised the importance of an international agreement on significant carbon reductions as the only long-term means of addressing climate change. A low target would reflect this logic, but ignore the significant economic costs of delaying action on emissions reductions – the longer we wait, the more it will cost to achieve significant carbon reductions.

The release of the supplementary report will provide the missing piece from the debate on the Government’s emissions trading scheme, although that debate has proceeded fairly vigorously in its absence. Not that the debate has always been particularly edifying. Yesterday, Michael Stutchbury lashed out at Fairfax commentators for calling the Business Council of Australia’s ETS submission “rentseeking” and criticising The Australian for promoting it. The piece had the crankiness of someone who has been sprung peddling garbage – which is what the BCA submission and the biased, badly-flawed “analysis” from Port Jackson Partners it is based on is.

You can bet The Oz will welcome a minimal emissions target using words like “sensible”, “moderate” and “realistic” and readily ignore the significant economic costs of not moving more quickly to reduce emissions. Some rentseekers have friends in high places.

To see more of Crikey’s coverage of the emissions trading scheme, visit the Hot Topic page here.