Rising sea levels, reduced rainfall and lack of snow in the Alps will combine over the next few decades to render the last 100 kilometers (60 miles) of the river useless because of saltwater intrusion, the experts predicted at a meeting in Parma on Monday.

About one-third of Italy's food production depends on freshwater from the Po River basin, according to Coldiretti, Italy's main farmers organisation.

Some 73 percent of the 2.5 billion cubic metres of water drawn each year from the Po is used for irrigation in a pattern that experts say is not sustainable.

Farmers will have to use more efficient irrigation techniques and drastically cut back on water-thirsty crops such as rice, corn and kiwi.

Vincenzo Ferrara, an Italian climate change expert, said Italian farmers use about 2,400 litres (600 gallons) of water to produce a kilo (two pounds) of grain, four times as much as Dutch farmers.

The Po River's debit has decreased by 20 to 25 percent over the past 30 years while water use has grown. Paradoxically, users are legally allowed 1,800 cubic metres per second, but the river's average debit is only 1,500 cms.

The experts noted that while farming practices will have to change, so will habits at home, warning that nearly half the water put to domestic uses is wasted.

The warning came as authorities said Monday that energy consumption in Italy was hovering near the record of 55,600 megawatts reached in July 2006, and the health ministry urged its employees to leave their ties at home in the hope of lowering the use of air conditioning.

A conference in Rome in September will aim to plan a national response to climate change.

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