The world’s largest mangrove forest, the Sundarbans, is increasingly becoming vulnerable to rising sea levels and frequent natural disasters.

The Sundarbans form an archipelago straddling India and Bangladesh, and are part of the delta of Ganga, Brahmaputra and Meghna basin. The Indian part of the delta comprises of 102 islands (of which only 54 islands are inhabited) in 19 blocks of West Bengal’s North 24 Parganas and South 24 Parganas districts.

About a million people in the Sundarbans coexist with 26 species of true mangroves, 234 species of birds and 47 species of mammals, including the Royal Bengal tiger, all of which face a threat from global warming.

Researchers of the School of Oceanographic Studies, Jadavpur University, estimate that the increase in the sea level every year is from 3.14 millimetres recorded till 2000 to about 8 millimetres in 2010.

Professor Sugato Hazra, director of the School of Oceanographic Studies said that 50,000 people were rendered homeless in the wake of cyclone Aila in May 2009, but there are no figures on how many of these climate change refugees have returned.

“Indian Sundarbans Delta: A Vision” a report prepared by the institute along with World Wide Fund For Nature-India (WWF) estimates that nearly one million people will become climate change refugees by the year 2050. To prevent this, the report suggests a planned retreat from vulnerable areas and more plantation of mangrove in the areas from where the people move away.

Anurag Danda, the WWF’s head of Sundarbans Landscape said that there are evidences that building embankments along the vulnerable islands will prove futile in the coming years.

Over the past decades some islands, both inhabited and uninhabited, have been consumed by the rising sea level. While an inhabited island, Lohachara, was lost to the sea in 1990, by 2000, another uninhabited island, New Moore was submerged in the Bay of Bengal.