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The rise in sea levels due to climate change is likely to turn the soil more saline in large parts of the Sundarbans region in India and Bangladesh, making cultivation unviable and forcing mass migration

As tidal river Durgaduani tears into their earthen embankments with every high tide, islanders living deep inside the Indian Sundarbans desperately try to save farms and homes (Photo by Manipadma Jena)

Increased soil salinity due to climate change-induced rises in sea levels is likely to force hundreds of thousands of coastal residents to migrate to inland areas in Bangladesh and India, particularly those living in and around the Sundarbans, the world’s largest mangrove forest in the Gangetic delta.

In Bangladesh alone, nearly 200,000 people living in coastal areas may be forced to migrate to inland areas in search of alternate livelihoods, according to a study from International Food Policy Research Institute (IFPRI).

In approximately 120 years, world’s coastal areas, currently home to 1.3 billion people, are likely to be inundated by the rise in sea levels. Bangladesh is under severe threat of future submergence, but studies show the migratory mobility from flooding is likely to be minimal, as most farmers have already adapted their cultivation practices to cope with changes in the frequency and intensity of flooding in this deltaic region.

However, given changes in the amplitude and frequency of sea level extremes, exacerbated by the still poor availability of high-saline tolerant crop varieties, increased soil salinity from rising seas will push nearly 200,000 to migrate from their coastal homes in Bangladesh, says the study Coastal Climate Change, Soil Salinity, and Human Migration in Bangladesh released last week.

“Our study shows increased soil salinity will push nearly 140,000 coastal residents to migrate to another location within their district, and nearly 60,000 would move to alternate districts,” said co-author Valerie Mueller, Assistant Professor at Arizona State University.

In the Indian Sundarbans, not addressed by the IFPRI study, the future may not be much better. “Sea-level rise combined with land subsidence has salt-contaminated farm lands to such an extent that already farming in low-lying islands is becoming unviable,” Tuhin Ghosh, Associate Professor at Jadavpur University’s School of Oceanographic Studies in Kolkata, told “Farmers are cultivating just enough for families’ needs, and they are trying to do it by themselves in order to cut costs.”

Consequently as availability of daily wage farm work has fallen, migration has increased, especially from high agricultural dependent areas that remain most sensitive to salt contamination and erosion of soil, he said.

The IFPRI study shows most migrants are likely to move to Dhaka, Bangladesh’s capital, or onward to neighbouring districts in the coastal region but few will move north while international migration too will fall. Only those with greater financial, human or social capital may take the giant step to move internationally.

It is increased aquaculture production in the coast, already underway, which will bring more job opportunities, reducing international migration. “So, people that would normally migrate abroad might be staying to take jobs that were made available by aquaculture production. Also, poorer households affected by the changes may have less money available for more expensive international migration,” said Joyce Chen, the other study author from Ohio State University. “As soil salinity increases from low to high levels, we (will) see a nearly 57% increase in share of earnings from aquaculture,” said Mueller.

Trapped population

For most households, however, the prohibitive costs associated with converting cropland to fish ponds deter diversification into aquaculture. The IFPRI study shows while 60,000 would move to alternate districts, the majority can only migrate to another location within their district, leaving them still vulnerable to sea-level rise in the long run.

Rice farms are increasingly converted to shrimp ponds in coastal Khulna division, southwest Bangladesh, as seawater pushes further in (Photo by Manipadma Jena)

“Financial constraints limit poor households from moving over longer distances, signalling a trapped population, raising concerns that the most vulnerable households may be the least resilient in the face of climate change,” said Chen.

Three of Bangladesh’s five largest cities are in the saline belt. Chittagong and Khulna districts are likely to witness highest intra-district migration, estimated between 15,000 and 30,000 migrants per year. These two districts contain the second and third largest cities in the country.

Distress migration

The highest migration from Indian Sundarbans is among men in the age group of 25-35. Their first destination is often to peri-urban areas for work in the service sector, as food delivery boys on 2-wheelers for online food ordering and delivery companies, security guards and rickshaw pullers.

Subsequently, many branch off to Tamil Nadu, Karnataka, Kerala, Uttar Pradesh and Uttarakhand, and increasingly to the Andaman Islands to work in the construction and brick-making sectors, according to Ghosh, who is leading an on-going qualitative study on migration.

During part of the year they work outside, men in 2017 remitted anything between INR 5,200 to INR 7,500 (USD 71-102) every month, while women sent an average of INR 4,000 (USD 55), according to the Indian Sundarbans study.

“With the government’s subsidised rice given under multiple schemes and remittances, families, usually older parents, wives and children left behind in Sundarbans, are now able to survive,” Ghosh said. “However stronger scientific data on salinity would substantially assist planned migration and other adaptive capacities,”

Food security at risk

“While it is true that the migrants will have to buy their own staple foods, it is possible that their earning potential may be greater in (migrant) receiving areas than had they stayed in staple crop production,” Mueller told via email. “On the one hand, farmers who switch from rice to fish production will likely benefit in the form of increased income. As farmers become richer, their demands for goods and services grow. The added demand for goods and services could encourage others to engage in the non-farm sector to provide those goods and services. In other words, the job creation could improve the income opportunities and purchasing power of those that remain behind.”

However, more research is needed to measure how food security changes among those who move and stay, before and after the move, Mueller said. “A two-pronged approach will be necessary to address this growing concern (of migration),” Mueller points out. This holds true of the Sundarbans on both sides of the international border between India and Bangladesh.

According to Mueller, governments may need to incentivise families that live in these key vulnerable areas to relocate, especially to detract movement away from population-dense areas, like Chittagong and Khulna. Secondly, policymakers may adopt more forward-looking development strategies to take advantage of the surplus labour provided by the coastal areas to promote modern economic activities, like manufacturing, in less populated areas. Such industries located in secondary towns can sustain job growth as more and more migrants reach these targeted locations.

The IFPRI researchers point out that infrastructure projects such as embankments and polders may have more limited success in future in these deltaic regions as saline contamination increases pressure to increase aquaculture which, in turn, increases the demand for brackish water.

Many instances in recent years have already been recorded here of shrimp farmers surreptitiously breaking earthen barricades of rice farms to let in fresh tidal waters. In other places, holes are drilled through protective embankments to pipe in saline water into fishponds. Embankment weakening and salt leaching are now common issues for local conflicts in these regions.


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