The Sundarbans is probably one of the most striking examples of how climate change is bringing largescale changes into ecosystems, impacting local biodiversity and livelihood.
The Sundarbans is probably one of the most striking examples of how climate change is bringing largescale changes into ecosystems, impacting local biodiversity and livelihood.
Spanning an area of 10,000 sq km in India’s West Bengal and southern Bangladesh, the Sundarbans consist of mangrove forests which constitute about two-fifths of the region’s overall surface area. It is considered to be a refuge for many animal species, many of them rare and endangered such as the Bengal tigers, estuarine crocodile and Indian python. The forests are also a home to over 250 bird species, otters, spotted deer, wild boar, three marine lizard species and five marine turtle species.
However, several studies have highlighted the vulnerability of this biodiversity-rich region to the rising threats of climate change and resource-intensive development. According to some estimates, a significant section of the Sundarbans could be lost to the sea, due to rising sea levels and coastal erosion.
A 2023 study published in the Springer Nature journal has, for instance, predicted the total area that is likely to by impacted by inundation by the end of the twenty-first century under different scenarios of seal level rise. Under the low scenario, Sundarbans is projected to experience land inundation of approximately 40 square kilometre (sq km), or 1 per cent of the total region. Under the moderate scenario, the study estimates an area of 72 sq km (1.8 per cent) to be inundated, and the high scenario could trigger land inundation of up to 136 sq km (3.4 per cent).
Another recent study suggested that the Indian Sundarbans mangroves could lose between 42 per cent and 80 per cent of their current area by the end of the century.
Climate change has thus put the Sundarbans at great risk, with rising sea levels causing significant losses in the eco-sensitive region. Coastal erosion and huge amounts of silt deposit along the estuaries have been transforming the regional landscape for years. Human activities like the encroachment of forest areas, industrial development and construction of new roads are contributing to the current crisis.
Between 1990 and 2016, West Bengal recorded the longest stretch of shoreline erosion in India, at 63 per cent, with 99 sq km of land being lost due to coastal erosion as reported by PTI. This, the report added, “has a direct impact on the landless, marginal residents of the Sundarbans who reside closest to the riverbank.”
Climate change has also been linked to a population decline among some of the animal species in the region due to a shrinking habitat. According to a Down To Earth report, the latest census conducted in 2023 revealed that the present tiger population in the Sundarbans (101) has almost saturated the nearly 2,585 sq km of notified forest area. The report quoted veteran wildlife and conservation scientist Yadvendradev Vikramsinh Jhala who had flagged the issue of a looming climate crisis impacting the tiger population in the Sundarbans. In the same report, Jhala contended that as far as the tiger habitat in the region is concerned, there is unlikely to be any significant changes in the near future.
The incidence and intensity of extreme weather events such as storms and cyclones are expected to increase with an increase in ocean surface temperature and sea level rise. Dubbed as the “Cyclone Capital of India”, the Sundarbans region was hit by five severe cyclones between 2019 and 2021—Fani, Amphan, Bulbul, Yaas and Jawad—causing widespread destruction and compounding ecological and human challenges, as per the Indian Meteorological Department (IMD).
Threat to Livelihood
There are more than 4.5 million people living on the Indian side of the Sundarbans. Inundation is an annual affair, with the sea swallowing several households across islands in the region, forcing the residents to relocate.
In the past two decades, climate change has displaced as many as 1.5 million people, and hit the livelihoods of an estimated 62 per cent of the local workforce, noted a report by The Hindu.
Due to the rising sea levels, there has been a rise in inundation and soil salinity in the past few years. As per World Bank’s estimates, many parts of the region are projected to reach near ocean-level salinity by 2050, rendering land unproductive for agriculture in the villages and contaminating drinking water sources.
Drinking water in the Indian Sunderbans mostly comes from deep tube wells. If its salinity exceeds one part per thousand (ppt), water is not considered potable. However, as of 2020, salinity in deep tube-well water exceeded 1 ppt in 17 of 50 hamlets in Gosaba, Hingalgunj, and Patharpratima blocks of the Sundarbans Reclaimed Region in India, noted the same World Bank study. The highest salinity (4.68 ppt) was recorded in the Karikarpara hamlet of Hingalgunj block, it added.
In the populated areas of the region, ground water from deep aquifers provide drinking water. Rivers such as the Saptamukhi, Thakuran, Matla, Bidya and Raimangal—flowing through the central and eastern parts of the region have lost their upstream connections with the Ganga which is their freshwater source. These rivers are fed by tides, leading to some areas with a riverwater salinity of 25 ppt.
Deep tube wells lift water from aquifers at a 900-foot depth or more. With climate change, these are becoming increasingly saline as upstream freshwater diminishes and ocean water diffuses further inland.
The United Nations predicts that the world could face a warming of as high as 3 degrees Celsius by 2100 if governments keep following the current climate policies. As the temperature rises, Sundarbans could be one of the first regions to be swallowed by the oceans.