Since 1996, when it first became legal to sell kangaroo meat for human consumption on Australia's eastern seaboard, the industry has slowly expanded to employ 4000 full-time workers and be worth $250 million a year.

It could become radically bigger if one proposal, tucked away in Professor Ross Garnaut's final report on climate change last month, is heeded.

The report suggests that one way of tackling climate change would be to switch from beef and sheep meat production to harvesting the low-emission marsupial.

The "enteric fermentation emissions" — the methane-rich burps and farts — of livestock (mainly sheep and cattle) account for about 67pc of Australia's agricultural emissions, the report says.

Cattle and sheep production also causes significant added emissions from agricultural soils, savanna fire and land clearing. The industry is also highly vulnerable to the "biophysical impacts" of climate change, such as water scarcity.

"(But) Australian marsupials emit negligible amounts of methane," says Garnaut. "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."

The Garnaut report includes modelling on the potential of kangaroos to replace sheep and cattle in Australia's rangelands. It concludes that by 2020, beef cattle and sheep numbers there could be reduced by 7 million and 36 million respectively. This would "create the opportunity" for an increase in kangaroo numbers from 34 million today to 240 million by 2020.

Meat production from 175 million kangaroos would be sufficient to replace all the forgone lamb and beef and would be more profitable when emissions permit prices exceed $40 per tonne of CO2-equivalent.

The net reduction in greenhouse gas emissions would be about 16 million metric tonnes of CO2-equivalent per year.

However, Garnaut adds, there are some "significant barriers" to such a change, including livestock and farm management issues, the gradual nature of change in food tastes and, perhaps particularly, consumer resistance.

John Kelly, chief executive of the Kangaroo Industries Association of Australia, adds that it would require a "paradigm change" in Australian agriculture and attitudes.

Indeed. Maryland Wilson, a vegan and president of the Australian Wildlife Protection Council, claimed last month that shooting kangaroos was like shooting "the spirit of Australia". She said it was cruel and that was one of the reasons little kangaroo meat is eaten.

Perhaps surprisingly, Gebhardt has some sympathy for the first bit. "I like kangaroos," he says as his four-wheeldrive bumps over a rough fenceline track on Coorona Station, north of Burra, 155 kilometres north of Adelaide. "They're just a nice animal, they're a nice emblem for Australia, it's nice to see them jumping around.

"But if they weren't controlled, I reckon they'd overrun the joint. They mightn't do a lot of damage on the inside country, other than the crops at certain times of the year.

"But here on the outside, the farmers rely on what little bit of grass is around for their sheep, so roos can be a bit of a pest."

And while at the supply side he might be boosting kangaroo consumption, he admits he's not helping at the consumer end.

He's tried it once: "Nothing wrong with it, it was quite nice, but I'm more a beef man. Set in my ways, I suppose."

But he bridles at Wilson's last claim. "Cruel?" he says. "I work bloody hard not to be cruel."

A SMALL mob of reds bobs up in the sweeping spotlight. At the first rifle crack one tumbles sideways and the rest break. After 10 or 20 metres, each stops and looks back in what seems a mix of bewilderment and curiosity. Within a minute four more are dead.

Gebhardt pulls up at the first body and takes a torch to look for the rest in a 200-metre semi-circle. He brings them back, cursing the nasty prickles in their coats. Each has been shot through the top of the head, the 55-grain ballistic tip bullet leaving a gaping wound. It isn't pretty, but clearly it's quick.

To be licensed as a kangaroo harvester, Gebhardt not only needed to be a cool and consistently accurate shot but undergo TAFE-approved training in regulatory controls and compliance and strict hygiene requirements before being assessed by two government departments.

A large part of his training centred on the animal welfare guidelines under the Federal Government's "code of practice for the humane shooting of kangaroos".

This specifies the minimum high-calibre firearms that can be used, and that all animals be shot in the head — "one shot to the brain". It also documents procedures for the humane dispatch of any pouch young.

Gebhardt prefers to avoid the need for the last. He assesses each target through the powerful scope, looking for the longer, stronger facial structures of males. "Most females this time of year are carrying young," he says. "So unless she's a big one, with nothing on her, I wouldn't consider it."

A female appears in the spotlight, a large bulge signifying she is carrying a good-sized joey. She hops along just in front of the vehicle, apparently unconcerned. "She must know something," says Gebhardt.

Gebhardt takes another precaution to ensure a clean kill: he reloads his own ammunition. There's a financial incentive, almost halving the cost of a factory round, but primarily it's about certainty.

"Factory loads are never consistent," he says. "One bullet might shoot spot-on, the next might drop, the next might have too much powder. I want spot-on every time."

He pulls on to a stony patch to dress the five reds. He learnt basic sheep butchery years ago from his slaughterman brother-in-law, and TAFE-training and the roo shooter whose territory he took over in July taught him how to field-process a macropod.

Changing into white butchers' gumboots, he lops off the lower joint of each hind limb with a cattle dehorner, like a large boltcutter, and snaps the tail about a third of the way down.

Western greys, or scrubbers, have that part of their tail cut away completely. He removes the head, cutting through the vertebrae at the base of the skull.

Gebhardt then eviscerates each animal, using a special knife with a small, blunt knob at its point, designed to avoid puncturing the gut and fouling the carcass. He pulls out the large grey mass of stomach and intestines, inspects it, and throws it aside. The liver, kidneys and heart remain. Foxes will clean up the discarded offal before daylight.

He attaches a government-issued plastic tag to each carcass. The tags — white for greys and orange for reds — are sequentially numbered and record the property on which the animal is killed. Later Gebhardt will use the tags to record the species, sex and weight of each animal, to be monitored by the state's National Parks authority.

Finally, the dressed kangaroos, which have been hanging from hooks on the side of the tray, are transferred to racks inside where they will be in the cooling breeze but protected from dust. Gebhardt bought the specially built stainless steel roo tray from his predecessor and it accounted for more than a quarter of his $30,000 start-up costs.

He also inherited his patch, the country around Burra and a series of stations in a circle starting about 35 kilometres out — places like Chalk Cliffs, Princess Royal and Poonunda. He has learnt kangaroo behaviour and knows to circle the dams on hot nights and move into the hill country when it's windy. He knows reds prefer the open, western greys like the scrub and euros stick to the hills. When water's scarce they'll move on to cropping country: "They make their way to greener pastures — and make my job a lot easier."

GEBHARDT's not the type to scoff, but he doesn't think there's much to Garnaut's proposal.

"I doubt you'd find many cockies round here turning their country over to the roos," he says. "It wouldn't fit the mindset. I think consumption will increase as time goes on because it's got all the protein people want and none of the fat, but I don't think it's going to trouble the sheep or cattle market. Ever. I just can't see it happening."

Kelly, of the Kangaroo Industries Association, says Garnaut's suggestion is perfectly feasible, if unlikely.

"You could do it tomorrow. There's very little that needs to be done in terms of a production system, it's simply a matter of a change of paradigm, an attitudinal change among pastoralists."

No one is suggesting farming roos, he points out.

"The concept is simply that in arid rangelands — around Broken Hill, Cobar, Charleville, that marginal sort of country — pastoralists might be better off destocking or partially destocking their country of sheep, claiming a carbon credit for doing so, and, heaven forbid, devoting a feed resource to kangaroos."

But to deliver the amount of carbon mitigation Garnaut suggests is possible, the kangaroo industry would have to increase production six or seven-fold. And that would require an enormous growth in the market.

"Myths, misconceptions and attitudes" towards kangaroo as a food are changing, he says, but the average annual quota of about 3 million (from a population of about 25 million within harvest areas) still accounts for 0.5pc of red meat consumed in Australia.

Loading the chiller at the Burra showgrounds, Gebhardt says he wouldn't mind more work but is content with what he's got for the moment.

"I enjoy it. I always wanted to do it. The extra dollars certainly help but it's a sport I've always enjoyed. It's just that now I get paid for it instead of shooting the money away."

Often he will take along his wife of 25 years, Jenny. She'll do some of the tagging, the bookwork, giving him time to get out and get a few more.

"But mainly it's a bit of company. It's nice and quiet out there. It gives us time to have a bit of a chat, to relax and talk. It's a good bit of time to have together. It's a nice life. I love it."