And out on the mulga country of Western NSW yesterday, the grazier Don Le Lievre was just as incredulous about Ross Garnaut's suggestion he should make a living from growing native vegetation for carbon credits instead of running cattle and sheep.

"It's just seems a joke," Mr Le Lievre said of Professor Garnaut's final report, which also advocates outback kangaroo farming.

More than half of agriculture's greenhouse emissions come from sheep and cattle belching methane, while kangaroos "emit negligible amounts", the report said.

Professor Garnaut said biosequestration - storing carbon in soils and vegetation by restoring mulga country - could give the outback a huge and economically transforming role in fighting climate change.

"Land-use change … has the capacity to transform Australia's, and to a lesser extent the global, mitigation effort. Getting the incentive structures right at home and abroad to realise the enormous potential for biosequestration is a major challenge, and potentially Australia's most important contribution to the global mitigation effort."

Uncertain about what carbon credits might be worth to him but certain that global food demand is growing, Mr Le Lievre has no plans to trade in his sheep and cattle. In the good times they eat native grasses and in the bad times they eat the mulga. "They do very well on [mulga]," he said. "Every tree's like half a bale of hay."

But the Garnaut report says of mulga country, "considerable degradation of these rangelands has been caused by marginal sheep and cattle grazing. It is estimated that these rangelands could absorb at least half of Australia's current annual emissions or some 250 million tonnes. A carbon price of $20 per tonne would provide up to a tenfold increase in income for property holders in this region if current practices were replaced by land restoration."