Every year, cyclones tear through the coastlines of South Asia, rivers swell beyond their banks, and seas creep further inland. Behind each of these events lies a quieter story: families packing up whatever they can carry and leaving home, often for good. Climate change is no longer just an environmental concern in this part of the world. It has become one of the most powerful forces reshaping where and how people live. With roughly a quarter of humanity packed into a region facing some of the planet’s harshest climate impacts, understanding the link between climate change and migration is essential to grasping the future of South Asia.
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Why South Asia sits on the frontline
South Asia is one of the most climatically vulnerable regions on Earth. Its long coastlines, melting Himalayan glaciers, monsoon-dependent farming, and densely populated river deltas combine to create conditions where even small climate shifts can uproot huge numbers of people. The region is home to about 25 percent of the world’s population, which means the human cost of climate disruption here is staggering.
The vulnerability is not spread evenly. People who depend on climate-sensitive livelihoods like agriculture and fishing are hit first and hardest. When a flood destroys a harvest or salt water ruins a paddy field, the families who relied on that land have few options left. Research consistently shows that low-income and lower-middle-income groups migrate far more often than wealthier populations, because they lack the savings and resources to rebuild in place. Climate change, in this sense, deepens existing inequalities rather than affecting everyone equally.
Sudden shocks and slow squeezes
Climate-induced migration is driven by two distinct types of events, and it helps to separate them.
Sudden-onset disasters are the dramatic, visible events: cyclones, flash floods, and storms that destroy homes within hours. Cyclone Aila displaced 2.3 million people in India in 2009, and in May 2020, Cyclone Amphan forced around three million people to evacuate while destroying or damaging nearly two million homes across India, Bangladesh, and Sri Lanka.
Slow-onset changes are harder to notice but just as destructive over time. Rising sea levels, prolonged droughts, soil salinity, and gradual coastal erosion quietly make land unlivable. These slow squeezes rarely make headlines, yet they steadily erode the ability of communities to survive, eventually pushing them to leave. Because the cause is gradual, the resulting migration is often misread as purely economic, which hides the climate driver behind it.
The scale of displacement
The numbers are sobering. More than 18 million people have already migrated within South Asian countries because of climate impacts. According to a report by ActionAid International and Climate Action Network South Asia, this figure could rise to nearly 63 million by 2050 if global warming continues on its current path, with as many as 45 million of those being from India alone.
The World Bank’s widely cited Groundswell research adds a global frame to this. It estimates that around 216 million people worldwide could be forced to migrate within their own countries by 2050 due to climate change, with over 50 million of them projected to be in South Asia. Importantly, these projections usually count only internal, slow-onset migration. They do not include people fleeing sudden disasters like floods and cyclones, which means the real totals are likely to be even higher.
The Sundarbans: a delta under siege
No single place captures the crisis better than the Sundarbans, the vast mangrove delta straddling the India-Bangladesh border. It is the world’s largest mangrove forest and a UNESCO World Heritage Site, but its millions of residents live on the edge of survival.
Sea levels here are rising at almost double the global average, while salinity and repeated cyclones turn fertile farmland into wasteland. The consequences are already visible. The islands of Lohachara, Suparibhanga, and Bedford have completely submerged, while Ghoramara has shrunk to a quarter of its original size, displacing thousands of people who relocated to the neighbouring island of Sagar. Tragically, Sagar itself is now facing disappearance as sea levels rise there at around 12 millimetres a year, meaning that even places of refuge are becoming unsafe.
When migration becomes the only option
For families in the Sundarbans, migration has become a coping strategy rather than a choice. As crops fail and fish stocks decline, men often migrate to distant cities for work, leaving women to manage households alone. Many move toward Kolkata, where the West Bengal State Action Plan on Climate Change has warned of further saline intrusion and loss of agricultural land. Those who arrive in the city frequently end up living in pavements and slums, recognised as economic migrants but rarely acknowledged as the climate migrants they actually are.
Looking ahead, the outlook is grim. Estimates suggest that around 1.5 million people may need to be permanently relocated out of the Sundarbans because sea level rise will eventually make life and livelihoods there impossible.
Migration as a development and governance challenge
Governments across the region face an uncomfortable reality: migration is increasingly used as a way to manage mounting environmental pressure. When a region can no longer support its population, relocating people becomes a tool for survival and, in theory, for sustainability. But moving people is not the same as protecting them. Researchers have warned that migration is not a feasible adaptation strategy on its own, because it can deepen climate-related injustice when states lack the capacity and resources to manage a smooth transition.
This is where the connection between climate and development becomes clear. Rural-to-urban migration drains agricultural regions of their workforce while straining already overstretched urban infrastructure. Cities receiving climate migrants struggle to provide housing, water, sanitation, and jobs. Without planning, climate displacement simply shifts poverty from the countryside to crowded city slums.
The legal vacuum
One of the deepest problems is that climate migrants exist in a legal grey zone. The term “climate refugee” is widely used in the media, yet it has no formal status under international law. The 1951 Refugee Convention does not cover people displaced by environmental change, and India is not even a signatory to that convention.
Domestically, the situation is no clearer. India has no legal category for climate migrants, no resettlement framework, and no targeted rehabilitation policy. Displaced people are instead lumped into broad categories like disaster victims or slum dwellers, none of which grant durable rights. The Disaster Management Act of 2005 focuses largely on short-term relief rather than long-term adaptation, treating displacement as a temporary inconvenience rather than a structural crisis.
There is, however, a constitutional foundation that advocates point to. Article 21 (the right to life) and Article 14 (the right to equality) together offer a basis for citizens to claim protection from climate harms, even though no dedicated climate displacement law exists to enforce these rights in practice.
Searching for solutions
So what can be done? Experts broadly agree on a two-pronged approach that addresses both ends of the migration journey.
At the source, the goal is to reduce the need to migrate in the first place. This means building climate-resilient infrastructure, promoting farming methods that protect soil, managing water more efficiently, and helping communities diversify their incomes so a single bad season does not force them out. The National Action Plan on Climate Change (NAPCC) has been suggested as an umbrella under which localised adaptation plans and even recognition of climate-displaced groups could be developed.
At the destination, the focus shifts to dignity and integration. Where relocation is unavoidable, authorities need to ensure that new land is safe and fertile, that tenure rights are secure, and that people have the resources to rebuild their lives. Some advocates have called for a dedicated climate refugee fund, separate from existing disaster funds, to finance this kind of long-term support.
Regional cooperation is the missing piece. Climate migration does not respect borders. Water shortages in Pakistan or sea level rise in Bangladesh and the Maldives could push people toward India in the years to come. Yet bodies like the South Asian Association for Regional Cooperation (SAARC) remain largely non-functional, leaving the region without a coordinated response to a shared threat. International frameworks like the 2018 Global Compact for Safe, Orderly and Regular Migration offer guidance, but turning that guidance into protection on the ground remains a work in progress.
The challenge is urgent, and the window for preparation is narrowing. Climate change is not waiting for policies to catch up, and the longer governments treat displacement as an afterthought, the more difficult and costly the eventual response will be.
What do you think? Should India and its neighbours create a distinct legal category for climate migrants, or would folding them into existing disaster and welfare systems be more practical? And given that climate migration crosses national borders so freely, how realistic is it to expect meaningful regional cooperation in a politically divided South Asia?
References
- https://link.springer.com/10.1007/978-981-99-8001-7_6-1
- https://link.springer.com/article/10.1007/s44282-025-00237-x
- https://www.wilsoncenter.org/article/climate-induced-displacement-south-asias-clear-and-present-danger
- https://www.deccanherald.com/amp/story/world%2Fclimate-change-could-create-63-million-migrants-in-south-asia-by-2050-45-million-indians-may-forced-to-move-report-928876.html
- https://asiasociety.org/india/events/climate-induced-migration-and-displacement
- https://www.visionofhumanity.org/climate-change-and-social-strain-threaten-the-peace-in-the-sundarbans/
- https://environmentalmigration.iom.int/blogs/triple-crisis-indian-sundarbans
- https://reliefweb.int/report/india/climate-change-displacement-and-managed-retreat-coastal-india
- https://questionofcities.org/climate-migrants-from-cyclone-hit-sundarbans-to-kolkatas-miserable-shanties/
- https://zerocarbon-analytics.org/policy/loss-and-damage-in-the-sundarbans/
- https://rli.blogs.sas.ac.uk/2025/10/15/climate-mobility-in-india-a-confused-understanding-of-climate-refugees-displacement-and-mobility/
- https://recordoflaw.in/climate-change-internal-displacement-and-the-right-to-life-assessing-indias-legal-framework/
- https://idronline.org/article/climate-emergency/india-needs-to-recognise-the-rights-of-climate-refugees/
- https://www.natstrat.org/articledetail/publications/climate-induced-displacement-in-south-asia-the-coming-challenge-170.html
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