Countries in the wealthy, high-emitting world are tightening migration controls just as environmental change is set to displace hundreds of millions of people.
Recent policy shifts illustrate the trend. The UK has introduced much tougher asylum rules and expanded grounds for deportation. In the US, proposed legislation would vastly increase enforcement and detention capacity, with plans that could add tens of billions of dollars for deportation operations, new detention centres and border infrastructure. The EU’s next budget envisions a major rise in spending on border management and an enlarged Frontex. Taken together, these moves point toward a strategy of physical and regulatory fortification: more walls, more policing, more removals.
Faced with climate-driven displacement, states have two clear options. One path is to share resources—funding large-scale adaptation where it is needed, supporting vulnerable communities, and cooperating to reduce pressure on land and livelihoods. The other is to protect access to livable land and resources by building barriers and enlarging enforcement capacity, pushing mobility into a securitized framework. Current policy signals from many rich countries suggest the latter is gaining ground.
Climate stress is already making parts of the world harder to live in. A 2020 Institute for Economics and Peace report estimated 2.6 billion people face high or extreme water stress today, rising to 5.4 billion by 2040. Droughts, heatwaves, floods, cyclones, failing harvests and conflict driven or worsened by environmental shocks will drive large-scale movement. The IEP warned up to 1.2 billion people might be displaced by 2050; the World Bank’s estimate for internal displacement is lower but still substantial, at roughly 216 million people by mid-century.
Most displacement will be internal. But internal migration often deepens inequality: wealthier, better-protected groups respond with gated developments, segregation and other security-driven measures. Many displaced people will also seek to cross international borders. Their motives are commonly described as economic, yet economic collapse is frequently a direct consequence of climate shocks—crop failure from drought, farmland lost to floods, wells ruined by saltwater intrusion—so separating climate and economic drivers is misleading.
There are stark inequalities in responsibility and vulnerability. The richest 1% emit roughly as much carbon as the poorest two-thirds, and historical emissions are concentrated in the global North. Those who have contributed least to greenhouse gases are often the least able to adapt and thus most likely to be forced to move.
At the same time, borders are being militarized. Over the past two decades more than 70 new international barriers have been constructed, from sections of the US–Mexico wall to fences on EU external frontiers and fortifications elsewhere. These structures often aim to control land and resources as much as to manage migration.
Legal and ethical questions intensify this dilemma. A 2025 International Court of Justice ruling underscored that states have responsibilities to address and, in some cases, compensate for climate harms—adding weight to arguments for cooperative responses rather than exclusion.
The choices made now will shape whether climate-driven displacement is met with solidarity—cooperation, investment in adaptation and fairer sharing of resources—or with securitized exclusion: expanded borders, detention and deportation that deepen global inequalities. Which path governments pursue will determine who is protected and who is pushed into precarious movement in a warming world.
Andrea Rigon is professor at Politecnico di Milano and UCL.
This article is republished from The Conversation under a Creative Commons license.
