Displacement along Bangladesh’s southern coast doesn’t always look like a disaster. Most of the time, it isn’t one. A field stops producing the way it used to. The nearest freshwater source dries up a little more each year. Someone’s son or husband leaves for the city because finding work at home has become increasingly difficult. Bit by bit, environmental change has worked its way into ordinary decisions about where people live and how they get by.
Geography is the main reason Bangladesh’s coast is so exposed. It’s low-lying, and it sits directly in the path of cyclones, tidal flooding, riverbank erosion, and rising salinity. None of this is theoretical. It’s already happening, and it’s hitting coastal communities hardest.
The scale of it is bigger than most people realize. An assessment by the International Organization for Migration, carried out in September and October 2025, put the number at 4.96 million people internally displaced by disasters across Bangladesh.[1][2] That’s not a projection — it’s an estimate of people who had already been displaced by disasters, and it shows the scale of the challenge communities were facing. Lance Bonneau, Chief of Mission of IOM Bangladesh, said the findings give national authorities, local leaders and development partners “a shared foundation to respond to displacement with greater clarity and coordination.”[2]
It’s worth being clear, though: not every case of climate migration involves a cyclone or a flood. Sometimes the damage is slower and harder to see. Salinity is one example — as it rises, it eats into the freshwater supply people rely on for drinking and farming. World Bank research has projected significant increases in river salinity across southwest coastal Bangladesh by 2050, with implications for dry-season agriculture, drinking water and the wider coastal ecosystem.[3][4]
But the link between environmental stress and migration isn’t as straightforward as it might sound. Research from the International Food Policy Research Institute, conducted with Ohio State University, found that rising soil salinity could push nearly 140,000 coastal residents to migrate within their own district each year, with another 60,000 moving to different districts altogether.[5] A separate study, however, complicates the picture further: researchers using an agent-based migration model found that in some Bangladeshi coastal districts, continued job opportunities in coastal cities could actually attract more people than they lose, even as sea levels rise.[6] And on the flip side, some of the most vulnerable households simply don’t have the resources to leave even if they wanted to. Whether someone migrates or stays often comes down to things like access to work, affordable housing, credit, or just having family nearby.
Looking further out, the pressure is expected to build. Under the World Bank’s Groundswell analysis, Bangladesh could see as many as 13.3 million internal climate migrants by 2050, in its more pessimistic scenario.[7] For South Asia as a whole, that high-end figure jumps to 40.5 million.[8] Worth repeating: these are projections, not certainties. What actually happens depends on how climate conditions, development, and adaptation efforts play out over the next few decades.
Most of this movement, notably, would take place inside Bangladesh’s own borders.[8] The World Bank expects climate-related migration hotspots to emerge within countries as climate pressures affect livelihoods and living conditions. [8] Dhaka in particular offers something many migrants are looking for — jobs, services, and a way to earn a living — but getting there doesn’t mean things get easier. A city doesn’t automatically offer stability just because it offers opportunity.
And that’s really the harder part of this story. A family that leaves the coast still needs somewhere to live, something to do for work, a school for the kids, a way to see a doctor when they’re sick. None of that comes with the move itself. Meanwhile, back on the coast, the people who stay behind are left facing the same eroding livelihoods and the same exposure to hazards — just with fewer neighbours around to share the burden.
So this isn’t really a simple story about people leaving the coast. It’s about what happens to livelihoods when the ground beneath them shifts, literally and otherwise — and whether Bangladesh’s cities and institutions are ready for what’s coming. A changing climate is reshaping the physical landscape. It’s reshaping people’s futures just as much.
References
International Organization for Migration: First nationwide estimate of disaster-induced internal displacement in Bangladesh
The Daily Star: Natural disasters internally displaced 4.96m — IOM
World Bank research on climate change and coastal salinity
ReliefWeb: Climate change-induced salinity affecting soil across coastal Bangladesh
The Daily Star: Thousands face forced migration
Environmental Research Letters: Research on coastal migration dynamics
World Bank: Key highlights of the Country Climate and Development Report for Bangladesh
World Bank: Groundswell — Preparing for Internal Climate Migration
Sheikh Muntaqim Ahmed Al Hasib
