Farmers in the drier parts of Australia could cut their greenhouse emissions and reduce their vulnerability to climate change by farming kangaroos instead of sheep and cattle, Ross Garnaut says.
He floats the radical idea in his final climate change report, after warning that cattle and sheep production is "highly vulnerable" to climate change.
This vulnerability, combined with extra production costs for animal methane emissions under a trading scheme, could encourage farmers to switch from sheep and cattle to kangaroos, the report says.
"Australian marsupials emit negligible amounts of methane from enteric fermentation," the report says.
"This could be a source of international comparative advantage for Australia in livestock production.
"For most of Australia's human history — around 60,000 years — kangaroo was the main source of meat. It could again become important."
Professor Garnaut cited research which investigated the potential for kangaroos to replace livestock in "Australia's rangelands" — drier parts of Australia where kangaroos are already harvested for meat.
Modelling showed that by 2020 rangeland sheep and cattle numbers could be cut by 36 million and 7 million respectively.
This would enable kangaroo numbers to jump from 34 million to 240 million by 2020.
Researchers estimated that the extra kangaroos would easily replace the beef and lamb production lost, and "meat production from kangaroos would become more profitable than cattle and sheep when emissions permit prices exceed $40 per tonne (of carbon)".
"The net reduction in … emissions would be about 16 megatonnes of carbon dioxide per year."
But Professor Garnaut's suggestion was dismissed by Mallee livestock and crop farmer Leonard Vallance.
"It really is an absurdity to suggest and it reflects very poorly on Garnaut that he would make such a suggestion," he said.
"Anyone that's ever had anything to do with kangaroos knows that they're a nomadic animal.
"The livestock that Western agriculture farms have been domesticated for 2000 years or more."
Mr Vallance said his Tempy farm would be on the edge of "the rangelands", given its location and average annual rainfall of under 300 millimetres.
If agriculture was included in an emissions trading scheme, farmers would be left with production costs they could not recoup and would be at a huge disadvantage to farmers overseas, he said.
Professor Garnaut conceded that more reliable ways were needed to estimate carbon emissions on farms before agriculture could be included in a trading scheme.
National Farmers Federation economist Charles McElhone was pleased the report recognised farming's complexities.
"We will deliver products that the market demands, and the commercial reality is that at this point … there is a limited marketplace for (kangaroo meat)."