Cyclone Yaas points to imminent climate disaster in Bengal

The Botanical Garden at Shivpur near Kolkata is an important tourist attraction and a renowned research centre. From the early 1970s, botanists there have tried to grow mangrove trees in a patch of the garden. But they could never create the suitable level of salinity in the fields that could help grow those trees.

Long after they had given up, a couple of years ago the then in-charge of the Botanical Garden, MU Sharief, happily announced the mangroves were growing on their own in the garden. The Garden authority dedicated a four-acre plot for a small mangrove forest with trees like garjan, hargoja, ora, and panlota. When these trees are full-grown, visitors will have the opportunity to visit a fascinating mini Sunderbans sans the dangers associated with it.

This may be exciting news for botanists and tourists, but it is also a grim pointer to an environmental disaster awaiting Bengal. Cyclone Yaas has corroborated this even if it did not wreak havoc in Bengal. But during the night before its landfall in Odisha’s Dhamra, it devastated the southernmost part of Bengal as the surge of the sea inundated its coastal towns of Digha, Tajpur and Mandarmani. Neither did it spare the islands near the coast nor the small towns by the river mouth, like Kakdwip and several others. This was not all. Seawater went deep inside the rivers and breached at least 134 man-made embankments. Large parts of the southernmost Bengal got waterlogged. Notably, this was saline water from the sea. It happened because it was the night of bhara kotal, the high tide on full-moon or no moon nights, backed by cyclonic weather.

So, what is happening? The answer is simple. The hungry tides of the rising sea are laying claims on the land of southern Bengal. A report by the National Centre for Coastal Research (NCCR), Ministry of Earth Sciences, said that West Bengal has recorded the maximum coastal erosion of 63 per cent (followed by Puducherry’s 57 per cent, Kerala’s 45 per cent and Tamil Nadu’s 41per cent) among all the Indian coastal states. But the people of the coast know this from their experiences.

Thirty years ago, the coastal tourist town of Digha had a natural beach. Now it survives thanks to boulders and guard walls built along the coastline. On the nights of bhara kotal, the sea breaches this guard wall and the water goes inside, even up to a couple of kilometres at places. The consequences of this advancement of the sea will be disastrous for Bengal and Bangladesh.

In 50 years from now, according to environmentalists, the Royal Bengal Tiger is likely to vanish from Bengal. Along with a large part of Bengal's coast, vast lands of the Sunderbans are likely to be claimed by hungry tides by then. While the rest of the coast can stall the doomsday by increasing the height of the guard walls, the sticky and half-submerged soil of the Sunderbans does not allow building such walls.

The water recedes from the Sunderbans during the low tide now, but 50 years later, a vast area of the forest, which has shrunk to about 5 thousand square kilometres, will remain perennially inundated. The tigers will die, but as the salinity of nearby areas will increase, the mangrove forest will start advancing northwards (both in India and Bangladesh). Consequently, a vast region to the north of the Sunderbans will lay waste as the soil will have a level of salinity that would allow only mangrove trees to grow.

All the rivers of the coast, including the Ganga, flow upstream during the high tide in the sea and breaching the banks will become routine for these rivers. It will affect thousands of square kilometres of agricultural lands of the entire South 24 Parganas district, parts of Purba Medinipur, North24 Parganas, Howrah and Hooghly districts as well. The lives of crores of farmers will be thrown out of gear as fertile agricultural lands that produce a huge quantity of food grains will be lost. Again, more than one-tenth of the landmass of Bengal will be inundated on every night of bhara khotal or during heavy rains. A large part of Kolkata will share this agony.

The calamity has already started unfolding itself. But the state and the Centre are concerned with the immediate. Elections come once in five years, so why would politicians be bothered about what will be lost gradually over many years and decades?

Meanwhile, according to research organisations, including the Central Pollution Control Board, Central Inland Capture Fisheries Research Institute, Jadavpur University’s Oceanographic Studies and the Department of Urban Welfare of the state government, the salinity level has increased even 150 km upstream of the estuary. The salinity level at Uluberia, a town on the west bank of the Ganga and 110 km north of the Sagar Island, has increased from 0.028ppt in 1985 to 0.132 ppt in 2013. At Barrackpore, 140 km upstream of the estuary, it has increased from 0.019 ppt in 1985 to 0.055 ppt by 2005. The salinity level will only increase every year. The mangrove trees growing naturally in the Botanical Garden or the surge of the sea even before Cyclone Yaas had its landfall in Odisha has rung alarm bells loud and clear. But is anybody listening? Perhaps not.

(Diptendra Raychaudhuri is a Kolkata-based journalist and author of the detective novel ‘Mirchi Memsaab’s House of Faith’)

Disclaimer: The views expressed above are the authors’ own. They do not necessarily reflect the views of DH.