Migration crisis: Climate change is trapping millions in harm’s way

Climate change is reshaping where people can safely live, but its fingerprints on migration are subtle. Seas are creeping higher, crops are failing more often, and droughts, storms, and wildfires are intensifying.

Yet when people explain why they move, few cite climate directly. That disconnect is the core of Hélène Benveniste’s work at Stanford’s Doerr School of Sustainability, where she pulls apart the climate signal from the many other forces that push and pull people across borders.

“Climate change influences pre-existing migration flows,” said Benveniste. “It increases the number forced to move and the number forced to stay.”

In other words, there is no single, tidy “climate migration” effect. The physics of a warming planet interact with local economies, politics, and social networks to amplify some flows and suppress others.

Who moves and who can’t

One consistent pattern has emerged across a decade of studies: people with middle incomes are the most likely to relocate in response to climate risks. They have enough resources to finance a move and enough exposure to feel the hit.

The poorest often want to leave but can’t afford it. The wealthiest can adapt in place. During the January 2025 Los Angeles wildfires, for example, some homeowners hired private firefighting crews to protect their properties, while others watched theirs burn. Money, in that case, bought options.

That gap between the desire to move and the ability to do so is widening. Benveniste and colleagues call it “involuntary immobility.”

In a 2022 study projecting global flows out to 2100, they estimated that emigration among low-income populations will be about 10 percent lower under climate change than in a scenario without warming.

Climate stress drains household resources – crop failures, lost wages, damaged homes – until travel becomes unaffordable. People remain in harm’s way.

Trapped in place

Nepal offers a vivid example. Many smallholder families cushion bad harvests by sending a worker abroad and living on remittances.

But when drought hits hard enough, those families lose both the income at home and the cash needed to fund migration. Their vulnerability compounds.

“The presence or absence of migration does not tell you everything,” Benveniste said. “A decrease in migration can signal rising vulnerability to environmental stress.”

Climate risk follows migration

Where people end up matters as much as whether they move. In a 2020 analysis with Princeton University colleagues, Benveniste asked whether migrants tend to land in places with lower climate risk than where they started.

On average, especially for those leaving lower- and middle-income countries, they do. That finding carries a sharp policy edge: the more restrictive a country’s border rules, the more it shrinks flows into safer zones and the more people it leaves in high-risk areas.

“They end up staying where they’re more exposed,” Benveniste said.

Heat, camps, and hard choices

The stakes are not abstract. By mid-century, nearly all refugee camps worldwide are projected to face more days of hazardous heat.

Some of the hottest sites could see twice as many days with wet-bulb temperatures above 86°F (30°C), a threshold at which even healthy bodies struggle to cool themselves.

Camps designed for temporary crises are becoming long-term homes exposed to extreme conditions. Those realities are forcing hard choices about how to adapt inside camps, including cooling, water, and shelter design.

Early experiments in climate cooperation

There are early signs of international cooperation, though they are uneven. In 2023, Australia and Tuvalu struck an agreement creating a path to permanent residency in Australia for Tuvaluan citizens as seas rise around the low-lying Pacific nation.

The pact drew criticism for giving Canberra veto power over Tuvalu’s security arrangements, but it set a practical precedent for linking climate risk to mobility.

Within the United Nations system, the Global Compact of Refugees, the UNHCR, and the UN Framework Convention on Climate Change are building tools to anticipate and manage climate-linked movement and immobility. Even so, Benveniste argues, “there is no clear governance framework at the international level that fully addresses these issues.”

Rethinking climate mobility

Her research points to a set of priorities that can be pursued now. Governments need to recognize where involuntary immobility is increasing. Support programs should aim to restore agency – either by enabling mobility or by strengthening local adaptation.

Border policies should be evaluated not only for their security or labor effects but also for how they change exposure to climate risk. Public systems – cooling centers, resilient housing, disaster insurance – must reach those who cannot buy private protection.

And humanitarian planning has to reckon with extreme heat in the very places that already bear the brunt of displacement. Above all, Benveniste’s work is a reminder that the absence of motion can be as telling as movement itself. Climate change won’t produce a single archetype of a “climate migrant.”

It will create more people who leave because they must and more who stay because they cannot. Seeing that nuance – who moves, who can’t, and why – will determine whether policy reduces risk or deepens it.

The study is published in the journal Nature Communications.

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