In Gabura, a river island in southwestern Bangladesh, the waiting room of the local health centre fills up before the doors even open. The women who arrive facing miscarriages, hormonal disruptions, high blood pressure, and skin diseases share something in common: their ailments can be traced back to the increasing levels of salt in fresh water sources. Rising sea levels, cyclones, and storm surges are inundating coastal lands with seawater. Human activities such as the conversion of agricultural land for shrimp farming, overextraction of groundwater, and the construction of upstream dams have also contributed to increasing coastal salinisation. When coastal homes become uninhabitable, families are forced into a costly and disruptive reality: migrating to nearby urban centres.
‘Where we now see water, our farming land used to be,’ said one farmer from Ta Dar U village in Myanmar’s Ayeyarwady Delta. Hundreds of villages have been submerged by extreme weather events and rising seas, turning what was once the ‘rice bowl of Asia’ during the British rule into a landscape of wastelands unfit for cultivation. But unlike Gabura or the Sundarbans, the communities of the Ayeyarwady face this alone. In a country with the longest ongoing conflict in the world and a military coup in 2021, a near-total collapse of institutional support and isolation from the international community has left entire populations without aid, recourse, and protection.
This is what climate change looks like in the littoral states of the Bay of Bengal—a harsh, lived reality of 450 million people. However, the crisis does not end here. Environmental stress triggers cascading effects: mass displacement that overwhelms urban infrastructure, economic shocks that deepen grievances, competition over shrinking resources, and the erosion of already fragile institutions. As these pressures converge across the Bay of Bengal, one of the most densely populated and politically volatile regions in the world, they threaten to overwhelm the existing governance frameworks, which were never designed to manage a crisis of this scale.
The displacement cascade
Climate-induced displacement across the region is not a future projection but an active, escalating crisis. The World Bank’s Groundswell report warns that by 2050, over 216 million people could be internally displaced, with South and Southeast Asia among the most affected.
Bangladesh has already absorbed more than 10 million climate migrants. Rising sea levels are predicted to submerge 17 percent of the country’s coastline, potentially displacing over 20 million people. In Myanmar, the devastation of Cyclone Nargis in 2008 killed over 140,000 people and permanently displaced hundreds of thousands. More recently, the cumulative impact of successive superstorms, including Cyclones Fani (2019), Amphan (2020), and Yaas (2021), shattered millions of homes and coastal livelihoods across both India and Bangladesh.
This cascade is not confined to the coastlines; it reaches deep into the region’s river networks. In Assam, the world’s largest river island, Majuli, has shrunk by two-thirds, even as its population doubled over recent decades. Annual floods now displace thousands every year, driving successive waves of inland migration away from the riverbeds and toward rapidly expanding urban centres.
When these climate migrants arrive in cities like Kolkata, Guwahati, Dhaka, and Yangon, they encounter a secondary crisis. Moving primarily from farming and fishing communities, these individuals possess ecosystem-specific knowledge, skills, and identities that hold little market value in an urban slum. Stripped of their livelihoods, they enter the urban landscape as informal labourers and squatters, existing without legal recognition, social protection, or proper resettlement. With limited access to resources, the displaced populations face deep economic and social disparities. This burden falls unevenly by gender: while men typically filter into low-wage, informal work in construction, hospitality, and transport, women have even fewer pathways for mobility, frequently leaving them trapped in precarious and exploitative conditions. Consequently, the cities absorbing this influx face compounding pressures on housing, water, health, and sanitation, pushing municipal infrastructure and governance frameworks to their breaking points.
The scale of displacement illustrated above does more than strain public infrastructure and finances; it actively creates the conditions for a third-order instability, exposing transboundary security and political fractures.
The climate, migration, and conflict nexus
While climate change rarely sparks conflict on its own, it acts as a powerful amplifier, exacerbating the drivers of instability and pushing fragile societies toward a breaking point. Security analysts call this the ‘threat multiplier’ effect—the phenomenon where environmental stress accelerates and deepens existing structural fractures, from ethnic tensions and resource competition to weak governance and political grievances.
Across the Bay of Bengal, this destabilisation is no longer a theoretical projection—it is actively altering the regional security architecture. In a region where political stability is already tenuous, climate stress does not just cause environmental damage; it triggers distinct, cascading security crises. It drives secondary displacement into the hands of criminal networks, fuels resource exploitation by authoritarian regimes, and weaponises pre-existing ethnic and political fault lines.
The most evident illustration is in the world’s largest refugee camps in Bangladesh’s Cox’s Bazar and Bhasan Char island, home to 1.2 million forcibly displaced Rohingya refugees from Myanmar. The overcrowded, disaster-prone camps also sit in the ‘hot zones for climate threats’, making them extremely vulnerable to cyclones, landslides, and flooding, which temporary shelters are entirely unequipped to withstand. The lack of adequate infrastructure and emergency response preparedness during disasters makes refugees susceptible to secondary displacement, with onward movements to neighbouring countries such as India, Indonesia, Malaysia, and Thailand.
Since the refugees do not have legal status, they become vulnerable to human rights violations. Stateless, undocumented populations with no legal recourse are often targets of armed groups, human traffickers, and criminal networks. In recent years, increasing competition between armed groups has resulted in a surge in violence and crime in these refugee camps. The Bangladesh Ministry of Defence has reported that at least eleven armed groups are operating in the camps, vying for greater control through drug smuggling, kidnapping refugees for ransom, forced recruitment and human trafficking. While climate vulnerability did not create this security breakdown, it has made an already desperate population more exploitable.
The gravity of the crisis has only intensified as Bangladesh’s newly elected government recently assumed power, inheriting fragile institutions responsible for managing the refugee crisis while maintaining political stability. Compounding this internal strain is a shift in the global humanitarian aid landscape. Significant cuts in US foreign assistance by the Trump administration have shut down most projects linked to climate, health, governance, and humanitarian assistance crucial for internal stability, leaving the country to navigate these overlapping emergencies with dwindling international support.
In Myanmar, the situation is quite distinct because it illustrates what happens when extreme climate stress meets complete institutional collapse, fuelling growing resentment against the state. Following the 2021 military coup, humanitarian organisations have been forced to severely curtail operations, leaving climate-displaced communities with little to no outside assistance. UN experts have warned that the junta, increasingly isolated and strapped for cash, has accelerated the exploitation of Myanmar’s natural resources, including timber, jade, and rare earth minerals, to fund its operations—degrading forests, polluting water sources, and actively worsening the climate vulnerability of the population it nominally governs.
When Cyclone Mocha struck in May 2023, the junta obstructed aid delivery to the affected communities. The burden of survival fell instead on already overstretched local networks, where competition for housing, water, and informal labour deepened existing inequalities. Unlike Bangladesh or India, where state institutions, however inadequate, still nominally function, Myanmar’s displaced populations exist in an almost complete governance vacuum where accumulated state failure and accelerating climate stress are feeding each other with no institutional capacity to intervene.
In India’s northeast, climate displacement has become legally and politically indistinguishable from ‘infiltration.’ Chronic flooding and riverbank erosion along the Brahmaputra river annually displace thousands of people, driving them from rural areas into Assam. This internal pressure is worsened by migrants crossing the porous borders from flood-ravaged Bangladesh. However, given that the politics of identity and migration is already a sensitive and politicised issue, the migrants arrive in a state that is already struggling to absorb its own displaced, further fuelling pre-existing socio-ethnic fault lines.
These fault lines are not simply political, but legally existential. They trace back to the early 1970s, when an influx of Bengali-speaking Muslim populations fled East Pakistan’s military persecution to seek refuge in India’s northeast. Over the decades, growing friction between indigenous Assamese and Muslim Bengali ‘infiltrators’ culminated in controversial pieces of legislation like the National Register of Citizens (NRC) and the Citizenship Amendment Act (CAA). Today, these policies have left about 1.9 million people facing potential statelessness and detention.
Consequently, any form of climate-induced displacement has been entirely subsumed into the electoral arithmetic of jati, mati, bheti, meaning community, land, and identity in Assamese. A farmer from coastal Bangladesh fleeing a cyclone and a person arriving for economic reasons are processed through the exact same security lens. The result is that climate adaptation and border security have collapsed into a single political question, wherein vulnerable people fleeing environmental collapse, rather than seeking opportunity, bear the heaviest cost.
However, in each of these cases, the decisive variable that transforms environmental stress into political crisis and insecurity is not the severity of the climate shock, but the underlying socio-political conditions, the governance mechanisms, and the fragility of the institutions meant to absorb it.
A crisis without framework and finance
These illustrated cascading effects: environmental collapse, mass displacement, and political instability, share a common thread—they are being managed in isolation. The regional and national governance frameworks have not evolved to respond to the interdisciplinary nature of emerging security risks.
The legal invisibility of climate migrants is the most fundamental gap. The 1951 UN Refugee Convention, the foundational international legal framework for protecting displaced populations, has no provision for climate-induced migration. Neither India nor most countries in the region have a legal category for climate migrants, leaving millions effectively invisible to the state institutions that are nominally responsible for their welfare. Fisherfolk families whose islands have gone underwater, farmers displaced by a cyclone, or communities whose agricultural lands have been permanently salinised—none of these people are recognised as displaced persons under any existing international framework. The governance vacuum this creates is consequential: without legal recognition, there is no recourse for resettlement, no entitlement to state support, and no mechanism for raising grievances.
This structural blindness is magnified by a severe gap in regional climate financing. For instance, Bangladesh alone requires a staggering $533 billion to implement its climate and displacement strategies, highlighting a broader regional crisis where frontline states, despite contributing negligibly to global emissions, 0.3 percent in this case, are left to fiscally absorb the immense cost of adaptation on their own.
As the primary regional grouping, BIMSTEC (Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation) has the capacity to build an integrated climate and security framework, but its current architecture is structurally fragmented. While member states successfully coordinate joint tri-service exercises for Humanitarian Assistance and Disaster Relief (HADR), this operational teamwork has not translated into integrated policy. BIMSTEC maintains separate verticals for climate and environment on one hand and security on the other, managed by separate ministries under disconnected frameworks with no coherent regional strategy. Furthermore, India, which leads the security vertical, has yet to formally integrate the climate-security nexus into its own national security architecture.
This institutional fragmentation also shapes BIMSTEC’s handling of Myanmar, where granting diplomatic legitimacy to the military regime after the 2021 coup has effectively paralysed regional accountability. Without any unified regional pressure or integrated security-humanitarian framework to bypass state obstruction, the junta has been able to weaponise international disaster relief and systematically block humanitarian aid from reaching opposition-held territories vulnerable to climate stress.
This stands in stark contrast to other multilateral groupings, where the climate-security nexus is increasingly reflected in mainstream policy. The European Union has integrated the ‘threat multiplier’ lens into its foreign policy, upgrading its early warning systems to flag climate-driven instability before it escalates, while the African Union and NATO have embedded climate security into their strategic frameworks. Volatile corridors such as the Sahel and the MENA region are often the default reference points for understanding how environmental stress interacts with conflict and instability. Yet, despite an equally acute convergence of climate vulnerability, political fragility, and strategic competition, the Bay of Bengal remains structurally ignored by both its own regional institutions and the international community.
Resolving these transboundary challenges requires BIMSTEC economies to move beyond isolated, national responses and joint HADR exercises. Instead, the region needs a coherent framework that integrates climate, displacement, and security into shared policies, cross-ministerial coordination, and community-driven, bottom-up adaptation. Without mobilising climate finance from multilateral development banks and the private sector at the required scale, any such framework risks remaining an aspiration rather than a policy, while the cascading effects of climate change continue to outpace the capacity to respond.
Geopolitics in a warming sea
The ecological instability and governance vacuum in the Bay of Bengal do not exist in a neutral space, it unfolds in a strategically important region where India, China, and the United States are competing for influence. In recent decades, China has steadily expanded its footprint across the region, deepening port investments in Kyaukphyu and Chittagong, reportedly upgrading military infrastructure on Myanmar’s Coco Islands, and building Bangladesh’s submarine base at Cox’s Bazar. This expanding influence in India’s maritime backyard has put New Delhi on high alert, with US defense reports flagging Bangladesh and Myanmar as potential locations for future Chinese military facilities.
Moreover, the Bay of Bengal is a vital maritime gateway to the Strait of Malacca chokepoint carrying the bulk of East Asian energy imports. It also holds untapped energy resources including deepwater hydrocarbon reserves, with infrastructure potential such as green grids under BIMSTEC promising economic integration. However, these investments are highly vulnerable to climate risks—rapidly intensifying cyclones, rising sea levels, and coastal erosion threaten critical port infrastructure and cross-border energy transmission lines.
As climate shocks accelerate domestic economic crises, agricultural collapse, and mass displacement, countries are increasingly prone to retreating towards defensive ‘resource nationalism’ to secure their own food and energy supplies. However, given the transboundary nature of these crises and the potential for climate-induced migration to trigger wider political instability, BIMSTEC countries will need a unified approach to managing these non-traditional security challenges.
The islands that once appeared on the maps of the Sundarbans, the world’s largest mangrove forest spanning over 10,000 sq km between India and Bangladesh—Lohachara, Suparibhanga, Bedford—no longer exist. Ghoramara, which has shrunk to a quarter of its original size, is following them under, displacing thousands to neighbouring islands. These are no longer isolated or localised tragedies. Each displacement ripples outward—into overcrowded cities without sufficient resources and infrastructure to absorb the new arrivals, and into border zones where climate migrants are not distinguished from ‘infiltrators.’ Stripped of legal standing, this expanding, invisible population becomes highly vulnerable to human trafficking and exploitation by criminal networks, thereby posing national and regional security risks. Until climate-induced displacement is treated as the security and governance crisis it already is, the cascading effects will continue to spread at an unmanageable scale.
Daksha Gupta is a Research Partnerships Officer at Chatham House, London. She holds an MA in Conflict, Security and Development from King’s College London. Find out more here.
