In 2021, the World Bank released a report titled Groundswell. Its central projection was stark: by 2050, as many as 216 million people across six world regions could be forced to move within their own countries due to climate change impacts — slow-onset disasters like water scarcity, crop failure, sea-level rise, and heat stress that make their current homes uninhabitable or unlivable.
That projection was based on moderate climate scenarios. In higher-emission pathways, the numbers are larger. And it addresses only internal migration — movement within national borders. The number of people crossing international borders as climate migrants could be equally significant.
To put 200 million in context: it is twice the total number of international migrants currently living outside their country of birth. It is larger than the population of Brazil. It would constitute the largest involuntary human movement in recorded history.
No legal framework is prepared for it. No political system is prepared for it. No receiving country has announced that it is prepared for it.
The climate migration crisis is not a future risk. It is a present reality that is going to get substantially larger.
Where It Is Already Happening
The abstractions of long-range climate projections can obscure the fact that climate-driven displacement is already underway at scale.
Bangladesh, one of the world’s most climate-vulnerable countries, loses significant portions of its coastal delta to flooding and salinity intrusion every year. The Buriganga River zone and the Sundarbans coastal region have already experienced population movements of hundreds of thousands. Dhaka, Bangladesh’s capital, has grown at extraordinary speed not only because of economic migration but because it is absorbing people displaced from increasingly unlivable coastal and riverine zones.
In the Sahel — the semi-arid belt across sub-Saharan Africa — prolonged drought, desertification, and the collapse of pastoral livelihoods have driven population movements across national borders for decades. The conflicts in Mali, Niger, and Sudan have climate dimensions that humanitarian framing often underemphasizes: competition for shrinking water and grazing resources underlies some of the violence that produces the refugees.
Pacific Island nations — Kiribati, Tuvalu, the Marshall Islands — face the prospect of entire national territories becoming uninhabitable due to sea-level rise and saltwater intrusion. Kiribati has purchased land in Fiji as a potential site for relocation. The president of Tuvalu addressed the COP26 summit in Glasgow standing knee-deep in the ocean to make visible what the numbers describe. These are small populations — tens of thousands — but they are the leading edge of a much larger displacement dynamic.
In the United States, managed retreat from flood-prone coastal areas is already underway in parts of Louisiana, where the state has funded buyout programs in communities that are flooding with increasing frequency. The Isle de Jean Charles Band of Biloxi-Chitimacha-Choctaw Indians became the first climate refugees in US history when the federal government funded their relocation in 2016. The community had lost 98% of its land to sea-level rise and coastal erosion.
The Drivers: Heat, Water, and Food
Three physical dynamics are primarily responsible for creating climate migrants.
Extreme heat is the most direct. Wet-bulb temperature — the combined measure of heat and humidity that determines whether the human body can cool itself through sweating — has threshold effects. Above approximately 35°C wet-bulb, the human body cannot cool itself even in shade, leading to organ failure and death within hours for healthy adults. Regions in South Asia, the Persian Gulf, and West Africa are already regularly approaching this threshold. Models project that by mid-century, under moderate warming scenarios, parts of these regions will exceed survivable wet-bulb temperatures for weeks per year. When an area becomes physically unable to support human outdoor activity or agriculture, migration is not a choice but a survival response.
Water stress affects both drinking water availability and agricultural production. Glaciers in the Hindu Kush and Himalayas supply freshwater to rivers that irrigate the farmland feeding hundreds of millions of people across South Asia. As those glaciers retreat, the rivers will first flood (from accelerated melt) and then shrink (as the ice reservoir is exhausted). The Ganges, Indus, Mekong, and Yellow Rivers all face this trajectory. When crop yields collapse, farmers move.
Sea-level rise directly threatens coastal populations through permanent inundation, saltwater intrusion into freshwater aquifers, and intensified storm surge damage. Currently, approximately 1 billion people live within 10 metres of current sea level. That does not mean they all face immediate displacement — coastal protection measures, managed retreat, and land reclamation can buy time — but it defines the zone of acute vulnerability.
The Legal and Political Gap
The 1951 Refugee Convention and its 1967 Protocol define who qualifies as a refugee and what protections they are entitled to. The definition is narrow: a refugee is someone unable to return to their country due to persecution based on race, religion, nationality, political opinion, or membership in a particular social group.
Climate change is not in that list. There is no internationally recognized legal status of “climate refugee.”
The consequences of this gap are not merely semantic. They determine whether displaced people are entitled to international protection, whether states have legal obligations toward them, and what resources the international humanitarian system is obligated to deploy. Without legal status, climate migrants are treated as economic migrants under domestic immigration law — subject to the same restrictions, barriers, and political controversies as any other unauthorized border crosser.
Several legal and policy efforts are underway to close this gap. New Zealand and Canada have created limited humanitarian pathways specifically for Pacific Island climate migrants. The Global Compact on Refugees, adopted by the UN General Assembly in 2018, acknowledges the role of climate change in displacement but creates no binding obligations. The UNHCR has adopted a broader interpretation of existing frameworks that can encompass some climate displacement scenarios, but the legal architecture remains fundamentally inadequate.
The politics of closing this gap are brutal. Countries with the legal and economic capacity to receive climate migrants are, in many cases, the countries where anti-immigration politics have been most successful in recent years. The prospect of legally recognizing hundreds of millions of people as having international protection claims is simply incompatible with the political direction of most high-income countries’ immigration systems.
Geopolitical Consequences
At the scale being projected, climate migration is not only a humanitarian issue. It is a geopolitical one.
Large-scale cross-border movements create pressure on destination countries’ housing, labour markets, public services, and social cohesion. They create bilateral tensions between countries of origin and destination. They create security challenges that military and intelligence agencies are increasingly planning for. They interact with existing ethnic, religious, and cultural tensions in ways that can produce political instability or violent conflict.
The risks are not evenly distributed. The countries most vulnerable to outmigration from climate impacts are often geographically adjacent to countries that are themselves under stress — the Sahel borders the Maghreb, which borders Europe. Bangladesh borders India, which faces its own climate pressures. The prospect of climate migrations cascading across regional systems — with each wave of displacement creating instability that generates further displacement — is one that strategic planners take seriously.
There is also a cruel asymmetry in responsibility. The countries most exposed to severe climate displacement — Bangladesh, Mali, Sudan, Small Island Developing States — have contributed minimally to the cumulative greenhouse gas emissions that have caused the problem. The countries most responsible for those emissions — the United States, European Union, China, and other major emitters — are geographically better positioned to absorb migrants. Whether the ethics of climate responsibility translate into any practical legal or political obligation is one of the defining questions of global climate justice in the coming decades.
What Is Required
The architecture of a meaningful response to climate migration has several components, and none of them will be easy.
Legal framework: Expanding the definition of protected displacement — either by amending existing refugee law or creating new treaty frameworks — to cover climate-induced displacement would establish the obligations that currently do not exist.
Financial mechanisms: The Loss and Damage Fund agreed at COP27 in Sharm el-Sheikh was a historic acknowledgment that climate impacts causing irreversible losses — including displacement — require financial compensation from major emitters. The amounts committed so far are a fraction of what the scale of need will require.
Managed migration pathways: Rather than waiting for crisis to force unmanaged flows, planned migration pathways — with integration support, skills recognition, and community preparation — could turn what is otherwise a chaotic process into a managed human response. New Zealand’s Pacific Access Category is a small but instructive model.
Adaptation investment: Some displacement can be deferred by investing in climate adaptation — sea walls, drought-resistant crops, early warning systems, managed retreat programs — that allow communities to remain viable in changing conditions longer. This requires sustained and frontloaded investment that is currently far below estimated need.
None of these responses is politically easy. All of them require international cooperation, substantial financial commitment, and willingness to prioritize long-term stability over short-term political advantage. The alternative is to wait for the displacement to happen and respond reactively — which is more expensive, more violent, and less humane than any planned alternative.
The climate migration crisis is arriving whether or not the world is ready. The only question is whether it arrives into a framework that manages it as the human challenge it is, or into a vacuum that treats it as a security problem to be fenced out.
Also explore:
Climate Change: Is It Too Late to Stop the Worst?
The Biggest Global Risks of the Next Decade
Water Wars: The Next Resource Conflict Will Be Over Drinking Water (coming August 17)
Africa’s Strategic Moment (coming August 10)
Related Articles
- The End of Academic Freedom: Understanding the Crisis
- Climate Lockdowns: Dystopian Future or Planet’s Last Hope?
- Why are religions dividing more than uniting? The faith crisis of the 21st century
Weekly Geopolitical Briefing
Go Beyond the Headlines
Analysis of the forces shaping the world - delivered every week. No noise, no bias, just depth.
Subscribe Free ?No spam. Unsubscribe anytime.
About the Author
António Monteiro
Engineer by profession, geopolitical analyst by conviction. I believe responsibility for the planet's future doesn't belong only to governments and institutions - it belongs to all of us. Knowledge about geopolitics, international conflicts, and the forces shaping the world is the most powerful tool for becoming more conscious, informed citizens. You don't need to be a diplomat to understand what's at stake - you just need to want to go beyond the headlines. At Outside The Case, I analyze conflicts, power dynamics, and global trends with rigor and accessible language, so you can understand what's really happening in the world.
Read more about the author →