The rising sea has devoured two of the nearly 100 tiny islands in the Sunderbans delta and threatening submergence of a dozen others having a population of over 10,000.
"Two islands, including Lohacharra, have already sunk in the sea and could not be sighted in satellite imagery," said Sugata Hazra, Director of the School of Oceanographic studies in Jadavpur University.
Attributing it to global warming, continuous erosion and depletion of the mangroves, Hazra said the situation has been assuming alarming proportions in case of a dozen other islands in the Sunderbans delta region.
The inference was drawn after a five-year systematic study was conducted by a team of scientists of the Oceanographic department at the instance of the Union Environment ministry, he said.
"The sinking process in the delta region started since the 1940s and it has now further accentuated," he said.
All the inhabitants of Lohacharra, which has already sunk, were shifted to nearby islands earlier.