They said that more than 70 per cent of beaches on the island of Kauai are eroding while Oahu has already lost a quarter of its sandy shoreline.  The islands have been experiencing a steady historical climb in sea levels dating back to the 19th century but the problem is likely to get significantly worse in coming decades as global warming causes sea levels to rise more rapidly.

Dolan Eversole, a coastal geologist at the University of Hawaii, said: "It will probably have occurred to a scale that we will have only been able to save a few places and maintain beaches, and the rest are kind of a write-off."

The vanishing sands could ultimately decimate Hawaii's economy. Tourism is the largest employer, with visitors spending more than $11 billion (£6.6 billion) a year.  It will also mean many animals and plans losing important habitats, including the Hawaiian monk seal and green sea turtles.

Hawaii is already trying desperately to bolster beaches in the tourist mecca of Waikiki, joining with hotels to spend $3 million (£1.8 million) pumping sand in from offshore.

Another option being considered is for the state to buy up properties along the sea front, tear them down and allow the beaches to shift inland.