The comprehensive report — to be handed to Prime Minister Kevin Rudd this morning — will outline how the country can move away from dirty coal-fired power, with modelling explaining the potential role of gas, clean coal technology and green energy forms such as wind and geothermal.
It will also outline how to cut greenhouse pollution in transport, agriculture and forestry, which are responsible for 37% of Australia's emissions.
But the message will come with a caveat: deep cuts in Australia will depend on reaching a strong global deal, which Professor Garnaut considers unlikely.
The 600-plus page report comes after three bruising weeks for Professor Garnaut following his previous report, which did not include final recommendations. That report faced criticism for its recommendation that Australia should agree to make a proportionate emissions cut of 10% below 2000 levels by 2020 as part of a limited but achievable global climate deal.
Climate scientists and environmentalists have damned the proposal, which would aim to initially stabilise carbon dioxide emissions at 550 parts per million. According to an earlier Garnaut report, it would give only a one-in-four chance of limiting global temperature rises to 2 degrees — the point considered the threshold for catastrophic famine, flooding and species extinction.
Sixteen authors with the Intergovernmental Panel on Climate Change have called on Mr Rudd to ignore Professor Garnaut's advice and set a minimum 2020 target of a 25% cut as a fair contribution to avoiding dangerous climate change.
A similar call was made by World Vision Australia chief Tim Costello, who issued a late appeal to Professor Garnaut warning that a global deal would be less likely if Australia set a weaker target.
"The suggestion that 550 parts per million might be the best we can do could become a self-fulfilling prophecy," Mr Costello said.
Professor Garnaut is expected to today stress a part of his last report that has largely been overlooked: that he believes Australia should still push for a target of stabilising carbon dioxide levels at a lower level — 450 parts per million — in the lead-up to the key UN meetings in Copenhagen next year.
This would require the Rudd Government to commit to a 25% emissions cut by 2020.
But Professor Garnaut is pessimistic about the likelihood of this target winning support, estimating it would require rich countries to cut emissions by 34% between 2012 and 2020.
It is believed the final report will stress that Treasury modelling shows Australia will remain prosperous and living standards will continue to improve if it agrees to deep cuts.