Representatives from countries around the world are convened in Baku, Azerbaijan, through Friday (November 22) for the United Nations Climate Change Conference, commonly known as the COP29, for ongoing talks on carbon emission reductions and the mitigation of climate-change-induced droughts, heatwaves, and rain. Among the long list of topics is what happens to people who live in the hardest-hit locations. We have already seen the impacts in the United States.

News reports suggest that after back-to-back Hurricanes Helene and Milton, some coastal residents of the southeast are ready to pack up and move. And yet, between 2021 and 2023, despite well-known risks from climate change, property values there continued to rise. Florida, in fact, was the fastest-growing state in the United States. Likewise, despite unprecedented heat waves and increasingly strained water supply, Arizona’s population has also continued to increase. 

Storms, droughts, flooding, heat—all these can affect people’s decisions about where to live or relocate, a phenomenon known as climate migration. However, as the push and pull of Florida’s weather on Americans shows, the relationship between climate change and migration is not direct or linear. 

There is a wide spectrum of possibilities for how climate change will shift where people remain and where they move, both in the United States and globally. Without concrete trend lines, there has been little consensus on how to plan for these coming changes. But writ large, we know what will happen: most people will stay put, some will have to leave, and those who move will need a place to land. And we can prepare now for all three contingencies.

Who is a Climate Migrant? 

Climate migration is, frankly, an overbroad term that refers to the movement of people from their homes—temporarily or permanently—because of climate-related changes or events. Yet, the truth is that we have little idea of how many people will become climate migrants due to the complex factors involved. Early estimate models were based on flawed assumptions, including that most people in climate “hotspots” would relocate and stay away permanently. One widely cited but debunked estimate posited that 1 billion people would become climate migrants by 2050. But that isn’t how it’s panning out so far.

Still, even the best current estimates have huge margins. The World Bank estimates that between 44 million and 216 million people will migrate within their countries due to climate change by 2050 (there is no parallel estimate for climate migration across borders.) Why such a vast range? Because there is a host of unknowns about the extent of climate change and humanity’s ability to stave off the worst scenarios.

Further complicating estimates, most climate migration due to natural disasters is temporary. Permanent climate migration tends to be caused by longer-term environmental changes. Globally, 32.6 million people were displaced by disasters in 2022, and 8.7 million remained so at the end of the year. Similarly, in 2022, 3.4 million people in the United States were displaced by a disaster, but only 500,000 had not returned home by 2023. Those rates of return could change, though, as such disasters increase in frequency and severity. A 2022 United Nations report estimates a 40 percent increase in disasters from 20215 to 2030 and a 30 percent increase in droughts from 2000 to 2030.

In short, it is hard to determine at a granular level who is and who isn’t a climate migrant. Most communities are or will be affected in some way by climate change. People typically have multiple reasons for moving, too. Climate change may be a factor, but it may be one among many; economic opportunity, social and cultural ties, government policies, scientific adaptation, and public safety may also play a role. If we can neither clearly identify who is a climate migrant nor forecast how many may be on the move, it is all the more challenging to develop policies. There are three buckets that future policies should fall into. 

Help People Stay

The majority of people impacted by climate change are not moving, either within their country or across borders. Most adapt in place. The right policies, planning, technology, and governance can help communities stay in place and even grow as climate change intensifies. Nation-states can take multiple approaches, including physical adaptation (e.g., building resilient infrastructure and technology) and social protection for vulnerable populations (e.g., public services for those who need it).

One way of adapting is by reducing disaster risks and costs. In the United States, each dollar spent on meeting the latest building codes can save up to $13 in avoided disaster damages. Examples include elevating homes in flood zones, adopting earthquake code requirements, or building flood walls. Engineering can prevent extreme dislocation. For example, half of the capital of the Pacific atoll country Tuvalu was projected to be underwater by 2050 due to sea level rise. Yet, with help from the United Nations and Australia, Tuvalu implemented a long-term plan to artificially raise the height of its land and invest in a sustainable water system.

Related to staying in place is building where we can stay. This means limiting or rolling back development in hazardous areas like floodplains or fire-prone wildlands. For example, from 2001 to 2019, 2.1 million acres of floodplain land were developed to build 844,000 housing units in the United States. And yet, in roughly the same period, from 2000 to 2020, 3.2 million Americans left neighborhoods with higher flood risks—what are now termed “climate abandonment areas.”

Preventing building in high-risk spots will require coordinated national approaches and evidence-based models of evolving risks. But the United States is not there yet. FEMA’s flood maps, which are relied on by communities to regulate land use and assess who needs flood insurance, have failed to keep up with climate change risks. In North Carolina, after 2016’s Hurricane Matthew, 75 percent of homeowners who applied for flood assistance were outside of the FEMA flood plain zones. The U.S. National Flood Insurance Program has paid for some homes to be repaired multiple times in flood-prone areas, although payments have slowed due to elevating construction and stormwater management.

Painful as it might be, our insurance markets are also going to have to continue to align premiums more accurately to environmental risks. Alarmingly, 39 million properties in the U.S. are insured at rates that do not reflect their true disaster risk, including flood, wildfire, and hurricane threats. Residents of Florida, Louisiana, and California are increasingly relying on state-run insurers of last resort, and many at-risk homes are becoming completely uninsurable. 

Help People Leave

Communities or individuals may need help moving elsewhere—mostly within their country, but rarely to another one.

Planned relocation is when governments help entire communities move from high-risk to safer locations in their country, typically when multiple hazards overlap in a location. Yet the strategy is considered a last resort because the process of abandoning a community has such a profound effect on its inhabitants. Since the 1970s, only 400 planned relocations have been identified across seventy-eight countries, most of them involving small numbers of people moving short distances. In the United States, for example, 500 households from Louisiana’s Isle de Jean Charles moved after coastal erosion shrank their island from 22,000 acres to 320 acres. 

Conversely, some people—trapped populations—are unable to leave worsening environmental conditions even if they want to because of a lack of resources or social networks. Such people may need government assistance when moving is necessary. During Hurricane Katrina, some residents of New Orleans—disproportionately Black and low-income—were unable to evacuate. Lacking cars, money, or other people to help them, these individuals were left behind to face the full brunt of the disaster. This phenomenon repeats in vulnerable areas globally.

It’s also worth noting that no government offers international migration based only on climate change. While some people have used the term “climate refugee,” people migrating because of climate change do not qualify for refugee status under U.S. or international law.

Refugee status would not be the optimal solution anyway. The global refugee system is overburdened trying to manage the roughly 120 million people displaced by violence—a number that has tripled over the last decade. Outcomes are poor. Refugee status often results in an inability to return home, limited educational opportunities, low labor market participation, and, for some, being trapped in limbo for generations without the rights of citizens in the countries where they reside. Adding millions of climate migrants to this overtaxed system would neither serve current refugees well nor offer meaningful support to the climate migrants.

However, some international pathways for climate migration will be needed. There are cases, such as small island countries like the Marshall Islands or Kiribati, that are projected to be underwater in the future, given trends. If they can’t adapt in place as Tuvalu is trying to do, governments should make general migration pathways, such as through work visas, more accessible.

Help People Land

Policies to address climate migration also must consider the effects on communities receiving a population influx and help them sustain and integrate migrants successfully.