Irrigated by one of the world's mightiest river systems, the Murray-Darling Basin yields nearly half of Australia's fresh produce. But the basin is ailing, and scientists fear that as climate change grips the driest inhabited continent, its main foodbowl could become a global warming ground zero.
The signs are already ominous: in the Riverland, one of the nation's major horticulture areas, dying vines and parched lemon trees attest to critical water shortages. Farmers have had their water allocations slashed during the recent crippling drought; 200 sold up, and many of those who hung on are struggling.
In Renmark, the region's oldest town, tales of hardship abound. Some families have spent their life savings; others are drowning in debt.
At one school, children have reportedly been stealing packed lunches from classmates. "That's how bad things have got, and I know people in those circumstances," says Jim Belehris, an almond grower.
Since the 1880s, when Europeans settled in the Riverland and began irrigating its arid soil, fruit and vegetable producers have depended on the broad River Murray. However, the river is in a sorry state, and this once lush area – at the southern end of the sprawling Murray-Darling Basin – faces a bleak future.
The picture is similar across the million-square-kilometre basin, which consists of vast inland plains crisscrossed by the Murray, Darling and numerous other rivers and tributaries. The reasons are complex.
The past half-century has witnessed an enormous – and officially sanctioned – over-extraction of water. The river system, which straddles four states and one territory, has been badly mismanaged. Falling commodity prices – and a glut of wine grapes – have exacerbated farmers' woes.
But it was the decade-long drought, the worst for more than 100 years, that tipped the balance. It also brought the basin's plight to public attention, with its images of skeletal cattle in cracked, brown paddocks and broad waterways reduced to muddy trickles.
And such spectacles, scientists say, will become increasingly common in Australia as the planet heats up.
According to the country's Department of Climate Change, global warming will trigger more frequent and severe droughts, as well as more devastating bushfires, cyclones and floods. The government's main scientific body, the Commonwealth Scientific and Industrial Research Organisation, says there is growing evidence that lower rainfall in south-eastern Australia is linked to global climate change.
Since 1910, the average temperature has risen by about 1C. Professor Anne Henderson-Sellers, a research fellow at Sydney's Macquarie University and a former director of the United Nations' World Climate Research Programme, says: "Australia is extremely vulnerable. Global warming is going to have an extraordinarily detrimental effect on us, more than on any other developed nation."
The challenges facing Australia include managing scarce water resources at a time of rapid population growth, and ensuring food security in a continent with only six per cent arable land. Because of its importance, and its precarious condition, the Murray-Darling Basin could become a flashpoint.
The government's climate change advisers have warned that agricultural production there could fall by 92 per cent by 2100.
Now, with Saturday's federal election looming, and following years of official inertia, the basin has become a political tug-of-war.
The Labor Prime Minister, Julia Gillard, and the opposition Liberal Party leader, Tony Abbott, have both promised millions of dollars to restore the river system – and the unique wetlands at the mouth of the Murray – to health.
Climate change, though, has barely rated a mention in the run-up to polling day. Both the main parties have ruled out a carbon tax; Ms Gillard has been ridiculed for proposing a "citizens' assembly" to gauge public support for an emissions trading scheme (ETS).
Kevin Rudd, who came to power in 2007 promising robust action on climate change, saw his popularity plummet after deferring an ETS. That led to Ms Gillard deposing him in June and calling an early election.
But her government has sidelined the issue – apparently afflicted by the same timidity that has prevented the global community from agreeing meaningful carbon emission reduction targets.
South Australia, Australia's driest state, is where the Murray ends its journey after winding through New South Wales and Victoria. South of Adelaide it spills into two freshwater lakes and into the internationally significant Coorong wetlands before exiting into the ocean. That, at least, is the theory.
Thanks to minuscule water flows, the Murray has not reached the sea since 1996, and only continual dredging has kept the mouth open.
The two lakes and the Coorong's lagoons have grown increasingly saline, threatening the numerous species of birds, fish and other creatures – some of them endangered – that rely on the mingling of sea and river water.
The casualties include hundreds of long-necked turtles, killed by a parasitic worm that thrives in salty water.
Garry Hera-Singh lives at Meningie, on the banks of Lake Albert, and has fished commercially all his life, like his father and grandfather before him. But the area where he catches yellow eye mullet, flounder, black bream and mulloway has shrunk by two-thirds.
The remaining waters are up to five to seven times saltier than the sea. "Nothing grows or lives in it; it's just a preservative," he says. "The whole eco-system is on life support. Salinity is gradually engulfing it, like a cancer."
In his youth, Mr Hera-Singh would see "huge flocks of birds that blacked out the sky". Not any more. When plenty of fresh water was flushing through, the region was alive with fish and aquatic weeds and insects.
"All I've seen lately is a massive loss of life. Watching the place die a slow death, as I have for the last 40 years – it makes you weep."
Once, there were dozens of dairy farmers around Meningie, irrigating their pastures with water from Lake Albert. Just a handful remain. Most gave up during the drought, which saw Albert – and its neighbour, Lake Alexandrina – recede by hundreds of metres, and fall below sea level for the first time in 7,000 years.
Lesley Fischer was forced to sell 700 cattle. She recalls desperately tough times. "We did whatever we could to keep our stock alive. We crawled on our bellies through the mud, to take pipes out to the lake. But there was that much salt in the water, it was making the cattle dehydrated.
"It was terrible, what happened to families around here. It got to the stage where a lot of the wives were watching each other's husbands. If you knew the wife was away, you'd ring up and make sure they were OK. Because those men, it was their life and they could see it disappearing in front of their eyes."
In the Riverland, north-east of Adelaide, the government is buying back growers' water licences in an attempt to relieve pressure on the Murray. Some farmers have taken up an offer of Aus$150,000 (£86,000) to relocate; first, though, they had to bulldoze their trees and pull out their vines.
Jim Belehris planted every one of his 10,000 almond trees – currently a profusion of pink blossom – himself.
But if nothing improves over the next five years, he will turn off the water and let them die. As for the next generation, he vows: "I'll burn those trees before I let my kids go anywhere near them."
Some believe that the Riverland – and other parts of the basin with marginal rainfall – should never have been farmed.
Water-intensive crops such as rice and cotton are grown in places that, without irrigation, would be virtual desert.
Mr Hera-Singh says: "The Romans and the Aztecs tried this thousands of years ago and failed."
He is cynical about the latest political promises. "They should have done something a long time ago, instead of waiting until communities were brought to their knees."
Facing competing demands from agriculture, industry, the environment and even cities – Adelaide depends on it for drinking water in drought times – the Murray is dying from the bottom up.
Along its banks, ancient red river gums have toppled over. The situation is particularly painful for the local Ngarrindjeri people. To them, the Coorong – sometimes called the "lungs of the Murray" – is a sacred creation site where their totems (native birds and creatures) breed.
Matt Rigney, chairman of a group of traditional owners, says: "There used to be 250 species of birds that would come into the beautiful mixed waters of the Coorong estuary.
"Everything was growing and alive there. Now, it's a pure saltwater system. It's very distressing. Our elders are getting sick, and a lot put it down to what's happening to our environment."
Despite temporary relief brought by water flowing down from floods in northern Australia, the prognosis for the Murray is grim. "This is a massive environmental disaster on our own doorstep," says Ms Fischer.
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