Coastal erosion threatens Indian Sundarbans

Local villagers have created a tall barrier of mud and rocks and the government of West Bengal has built a long concrete structure. But this has not prevented large-scale coastal erosion and sea-level rise day after day and year after year in the Indian part of the Sundarban mangroves.

There are alarming and life-threatening consequences. Humans and tigers are facing shrinking habitats with the ocean swallowing up land in the world’s largest mangrove. This region in the Bay of Bengal consists of 102 islands, about half of them inhabited. The sea level has risen by an average of 3 centimeters a year over the past two decades in the Sundarbans, leading to one of the fastest rates of coastal erosion in the world.

Homes have been inundated and ground soil contaminated by salt water forcing residents to relocate. Tiger hunting grounds have shrunk, leading them to target humans and livestock alike. At the same time, villagers are venturing into tiger territory, putting them at even greater risk of tiger attacks.

Sundarbans is the world’s largest contiguous mangrove forest and is a designated world heritage site. The habitat supports approximately 4.37 million people. Research shows that it is believed the Sundarbans has soaked in millions of tonnes of carbon dioxide. However, the Sundarbans faces several challenges due to climate change.

Experts say that with rising sea levels, islands are disappearing and the increasing salinity in the water and soil has severely threatened the health of mangrove forests and the quality of soil and crops. Additionally, there have been serious disturbances to hydrological parameters and change in fishing patterns, resulting in disastrous consequences for fishermen. Frequent cyclones and erratic monsoon rain pattern are damaging ecology and humanity.

According to the Climate Hot Map offered by the Union of Concerned Scientists (UCS), without the mangroves of the Sundarbans to serve as a buffer, more frequent and intense storms are likely to pose a growing danger to the residents of Ganges basin including cities like Kolkata (Calcutta).

Another study, ‘Living on the Edge: Climate Change and Uncertainty in the Indian Sundarbans’, points out that the delta faces significant climatic and other ecological challenges (e.g. disappearing mangrove forest, islands affected by rising sea levels, erratic rainfall and cyclones). The residents are largely landless subsisting on agriculture and fishing. Poverty and deprivation are both high, with migration emerging as a major development issue in recent years. In the past decades, climate change stressors such as a rising sea level, land erosion, erratic patterns of rainfall and temperature have been profoundly changing the ecology, lives and livelihoods in the Sundarbans.

The study states that climate change related impacts and uncertainties are increasing with time as documented by local people and through scientific data. However, it points out that there are some seeds of change and emerging alternative pathways, “There have been experiments between agricultural scientists, non-governmental organisations and local people to bring back salinity resistant traditional paddy crops. These could bring about changes in the agricultural practices which can help farmers to build climate resilient crop production systems, especially those who have land which is not yet eroded. There are also similar experiments around culturing different fish and prawn species that can tolerate salinity. Similarly brackish aquaculture can be a sustainable options for the islanders as the market players like exporters, are showing interest in this alternative. While these alternative pathways can help build local resilience it is important that they are accessible and affordable to the poorest of the poor, especially in a region where most of the people are below the poverty line.”

On the Bangladeshi side of the Sundarbans, a recent study has warned that the Royal Bengal Tigers could be extinct within 50 years because of the constant rise in sea levels, and climate change. The study titled ‘Combined Effects of Climate Change and Sea-Level Rise Project Dramatic Habitat Loss of the Globally-Endangered Bengal Tiger in the Bangladesh Sundarbans’, has revealed that the constant rise in sea levels and climate change could bring a catastrophic situation to the mangroves of the Sundarbans; the iconic Bengal tiger’s last coastal stronghold and the world’s biggest mangrove forest.

The study, carried out by a team of Bangladeshi and Australian scientists, was published in the journal ‘Science of The Total Environment’. The team used computer simulations to assess the future suitability of the region for tigers and their prey species, using mainstream estimates of climatic trends from the Intergovernmental Panel on Climate Change.