The drought in Australia's main food bowl, the Murray-Darling Basin, has worsened, with record low inflows into the river system in June and an even gloomier situation predicted for the coming months.
Neil Plummer, acting head of the National Climate Centre, described rainfall during the southern hemisphere autumn as "an absolute shocker", and said: "I'm gasping for good news". Wendy Craik, chief executive of the Murray-Darling Basin Commission, said the river system's condition was "critical... tending towards flatlining". She added: "We have got it on life support."
The basin, which straddles four states and is the size of France and Germany combined, produces 41 per cent of Australia's fruit, vegetables and grain. Agricultural products worth more than £10bn are exported from the region annually to Asia and the Middle East.
But flows of water last month into the two mighty rivers that irrigate the basin were the lowest since records began 117 years ago, equating to only 16 per cent of the June average. During February to June, the levels were only marginally higher than last year, which was the driest autumn on record.
The dire assessment of the rivers' health came only a few days after government scientists warned that Australia – the world's driest populated continent – could expect the frequency of heatwaves to increase tenfold, from once every 22 years to every one or two years. They also predicted that droughts would occur twice as often and affect twice the usual area. The findings were described by the Agriculture Minister, Tony Burke, as reading "more like a disaster novel than a scientific report".
The state of the Murray-Darling is of great concern to two groups: farmers and environmentalists. The former depend on it to irrigate crops such as rice, grapes and horticulture. The latter point to scientific reports saying the river system's unique ecology could be irreversibly damaged by October without heavy rain.
Salvation seems unlikely. Dr Craik said yesterday that hopes of drought-breaking winter rains had faded, and low inflows were expected for the rest of the year. Temperatures are forecast to be above average for the next three months, which means rain is more likely to soak into the sun-baked earth or evaporate than flow into the rivers.
Mr Plummer said good rains early in the year had barely dented the drought, and long-term trends pointed to six to seven years of below average rain in each decade. Of recent months, he said: "Autumn can only be described as an absolute shocker in terms of climate conditions for the basin."
Scientists say the lower reaches of the Murray, where lakes and vast wetlands meet the sea, are almost "beyond recovery", with wetlands dried up, vegetation lost, some native fish species wiped out and others facing extinction. The lakes are becoming acidic, and wildlife habitats are under threat.
Dr Craik raised the pros-pect that communities dependent on the Murray's tributaries might have to have water trucked in. "Regrettably, the drought is getting worse," she said.
Australia's most punishing drought in a century has forced about 10,000 farming families off the land, and threatened the economic viability of some agricultural towns. Ross Garnaut, the government's chief climate change adviser, warned in a report last week that irrigated agricultural production in the Murray-Darling Basin would decline by 92 per cent by 2100.
The drought, which began six or seven years ago, and has been particularly crippling over the past 12 months and has wiped more than $20bn (£9.3m ) off the economy since 2002.
Even if rainfall returns to average levels, the basin area – the source of 70 per cent of Australia's irrigated agriculture – will continue to suffer because of higher temperatures. Meteorologists have established that for every one degree Celsius rise in temperature, inflows into the river system decrease by 15 per cent.
"The catchments are very dry," said Dr Craik. "And the outlook, unfortunately, for rain is drier than average. Put all that together, and you don't have a very encouraging scenario."