Rising seas, caused by global warming, have for the first time washed an inhabited island off the face of the Earth. The obliteration of Lohachara island, in India's part of the Sundarbans where the Ganges and the Brahmaputra rivers empty into the Bay of Bengal, marks the moment when one of the most apocalyptic predictions of environmentalists and climate scientists has started coming true.

As the seas continue to swell, they will swallow whole island nations, from the Maldives to the Marshall Islands, inundate vast areas of countries from Bangladesh to Egypt, and submerge parts of scores of coastal cities.

Eight years ago, the first uninhabited islands - in the Pacific atoll nation of Kiribati - vanished beneath the waves. The people of low-lying islands in Vanuatu, also in the Pacific, have been evacuated as a precaution, but the land still juts above the sea. The disappearance of Lohachara, once home to 10,000 people, is unprecedented.

Kiribati is pleading for help, its Government asking the New Zealand Government to accept at least the educated population from Kiribati. The highest point of Kiribati's islands is only 3 meters.

 So remote are the islands that the researchers first learned of their submergence, and that of an uninhabited neighbouring island, Suparibhanga, when they saw they had vanished from satellite pictures.

Two-thirds of nearby populated island Ghoramara has also been permanently inundated. Dr Sugata Hazra, director of the university's School of Oceanographic Studies, says "it is only a matter of some years" before it is swallowed up too. Dr Hazra says there are now a dozen "vanishing islands" in India's part of the delta. The area's 400 tigers are also in danger.

Until now the Carteret Islands off Papua New Guinea were expected to be the first populated ones to disappear, in about eight years' time, but Lohachara has beaten them to the dubious distinction.

Human cost of global warming: Rising seas will soon make 70,000 people homeless

Refugees from the vanished Lohachara island and the disappearing Ghoramara island have fled to Sagar, but this island has already lost 7,500 acres of land to the sea. In all, a dozen islands, home to 70,000 people, are in danger of being submerged by the rising seas.

Russian scientists have predicted not just islands, rather parts of countries would start disappearing within the next five years.