Australian researchers say they have identified vast reserves of fresh water trapped beneath the ocean floor off Australia, China, North American and South America

Australian researchers said Thursday they had established the existence of vast freshwater reserves trapped beneath the ocean floor which could sustain future generations as current sources dwindle.

Lead author Vincent Post, from Australia's Flinders University, said that an estimated 500,000 cubic kilometres (120,000 cubic miles) of low-salinity  had been found buried beneath the seabed on continental shelves off Australia, China, North America and South Africa.

"The volume of this water resource is a hundred times greater than the amount we've extracted from the Earth's sub-surface in the past century since 1900," said Post of the study, published in the latest edition of Nature.

"Freshwater on our planet is increasingly under stress and strain so the discovery of significant new stores off the coast is very exciting.

"It means that more options can be considered to help reduce the impact of droughts and continental water shortages."

UN Water, the United Nations' water agency, estimates that water use has been growing at more than twice the rate of population in the last century due to demands such as irrigated agriculture and meat production.

More than 40 percent of the world's population already live in conditions of . By 2030, UN Water estimates that 47 percent of people will exist under high water stress.

Post said his team's findings were drawn from a review of seafloor water studies done for scientific or oil and gas exploration purposes.

"By combining all this information we've demonstrated that the freshwater below the seafloor is a common finding, and not some anomaly that only occurs under very special circumstances," he told AFP.

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