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How does climate change affect migration?

April 2021 saw a 20-year high in the number of people stopped at the U.S./Mexico border, and President Joe Biden recently raised the cap on annual refugee admissions. Stanford researchers discuss how climate change’s effect on migration will change, how we can prepare for the impacts and what kind of policies could help alleviate the issue.

In the face of a mounting humanitarian crisis at the U.S./Mexico border, the Biden administration has acknowledged climate change among the powerful forces pushing migrants from Central America. A $4 billion federal commitment to address the root causes of irregular migration acknowledges the need for adaptation efforts to help alleviate the situation.

Homes in Nicaragua flooded by Hurricane Eta

The challenge is not limited to the border. Last year, weather-related disasters around the world uprooted 30 million people – more than the population of the 14 largest U.S. cities combined – and wildfires displaced more than a million Americans, according to the Internal Displacement Monitoring Centre.

Below, Stanford climate and behavior experts discuss how climate change’s effect on migration will change, how we can prepare for the impacts and what kind of policies could help alleviate the issue. The researchers include Chris Field , a climate scientist who has led UN Intergovernmental Panel on Climate Change efforts to analyze climate-related risks, impacts and adaptation opportunities; Gabrielle Wong-Parodi , a behavioral scientist who studies how people react to challenges associated with global environmental change; Erica Bower , a PhD student who studies human mobility in the context of climate change impacts and served as a climate change and disaster displacement specialist at the UN Office of the High Commissioner for Refugees; Nina Berlin Rubin , a PhD student in Earth system science whose research focuses on decision-making in the face of climate extremes.

What is a common story of climate migration in the U.S./Mexico?

Bower : Climate change is a threat multiplier – it can exacerbate economic insecurity or political instability, which in turn may lead to migration. In the “dry corridor” of Central America, for example, climate change extremes such as droughts may hinder crop production. Without a consistent source of food or income, a farmer may seek other livelihood opportunities in a nearby city or further north. When combined with poverty or violence, a drought may make the perilous journey north seem to be a more promising adaptation or survival strategy.

How has climate change’s effect on the tide of refugees in the U.S./Mexico border changed in recent years?

Bower : In recent years, climate change has made extreme weather events stronger and more frequent, which may contribute to migration decisions. However, given the multiple reasons why people move, we do not have the evidence required to say with certainty precisely how climate change has affected net migration flows to the U.S./Mexico border.

What does the future hold for climate-related migration at the border? What should we expect, and how should we prepare for it?

Field : In the long run, stopping climate change is a key element of getting the situation under control. In the short run, there are lots of effective ways to decrease vulnerability. These range from improving agricultural practices to strengthening social safety nets. Across the full suite of possible vulnerability reduction measures, it is critical that the solutions are implemented in partnership with local communities and not imposed on them. In regions with high levels of corruption or political or criminal violence, it is much more challenging to make progress on vulnerability reduction.

Bower : We may need to change our approach to welcoming people across our southern border. The definition of refugee in international law is very narrow, and most people fleeing in climate change contexts – including from Central America to the U.S./Mexico border – are generally not recognized as refugees under international or domestic law. Newly proposed legislation in Congress would protect the human rights of people fleeing to the U.S. in the context of climate change.

Leaving is only half the story. Tracking these migration pathways from origin to destination can speak to whether people are moving to safer areas or to areas that introduce new or heightened risks. ” Nina Berlin Rubin PhD student, Department of Earth System Science

How extensive is climate change’s effect on migration within the U.S.?

Wong-Parodi : We are seeing some evidence that people who feel more impacted by wildfires and secondary impacts like smoke are more likely to intend to move to a new state within the U.S. or even out of the country. The question that remains is whether the destination they are planning on moving to is more or less at risk for wildfires or other climate hazards.

Berlin Rubin : Exactly. One might decide to uproot their family and leave behind friends and neighbors in search of respite from wildfires and smoke, only to find themselves living somewhere with just as much wildfire risk – or exposure to other risks like flooding – as where they were before. And the reality is, as these fires become more frequent and destructive, people will have fewer options and less confidence that their destination is actually going to be free from wildfires.

Bower : We are also seeing that many communities are seeking government support to relocate away from sea level rise or flooding. A recent mapping exercise identified 36 cases of community-wide relocation in the U.S. alone since 1970.

How might federal and state policy lessen climate change’s impact role as a driver of migration at the border and within the U.S.?

Field : The U.S. Federal government can play a large role in addressing the core drivers of displacement, through three main pathways. It can decrease its contribution to warming through decreasing its greenhouse gas emissions. It can help other countries decrease their emissions through financial and technical assistance. It can also help poor countries adapt so that their people feel less pressure to migrate. This last pathway has the potential to be especially cost-effective in the near term, even though it cannot address all of the drivers of migration.

Is there any promising research/data gathering that could dramatically change how we understand and react to this challenge?

Field : It is likely that progress in decreasing pressure to migrate will require patience. One area where data can make a big difference is in cataloging investments in adaptation and following their consequences. At this point, we are not systematically cataloging and tracking adaptation efforts. A robust database can be the foundation for a new generation of evidence-based adaptation.

Berlin Rubin : Research at the individual level will help us better understand and characterize the psychosocial and experiential factors that motivate climate-related migration decisions. But leaving is only half the story. Tracking these migration pathways from origin to destination can speak to whether people are moving to safer areas or to areas that introduce new or heightened risks. We need to understand the local context in which people are making their decisions in order to get ahead of these challenges.

Field is the Perry L. McCarty Director of the Stanford Woods Institute for the Environment , the Melvin and Joan Lane Professor for Interdisciplinary Environmental Studies, a professor of Earth system science and biology and a senior fellow at the Precourt Institute for Energy . Wong-Parodi is an assistant professor of Earth system science in the School of Earth, Energy & Environmental Sciences ; and a center fellow at the Stanford Woods Institute for the Environment . Bower is a PhD student in the Emmett Interdisciplinary Program in Environment and Resources at Stanford’s School of Earth, Energy & Environmental Sciences.

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Media Contacts

Chris Field Stanford Woods Institute for the Environment (650) 823-5326; [email protected]

Gabrielle Wong-Parodi School of Earth, Energy & Environmental Sciences (650) 725-6457; [email protected]

Erica Bower School of Earth, Energy & Environmental Sciences (203) 666-9892; [email protected]

Nina Berlin Rubin School of Earth, Energy & Environmental Sciences (307) 690-4234; [email protected]

Rob Jordan Stanford Woods Institute for the Environment (650) 721-1881; [email protected]

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How climate-driven migration could change the face of the U.S.

Dave Davies

ProPublica reporter Abrahm Lustgarten says millions of Americans are likely to move in the coming decades to escape wildfires, rising seas, oppressive heat and drought. His new book is On the Move.

NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.

The climate crisis, migration, and refugees

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John podesta john podesta founder and director - the center for american progress.

July 25, 2019

18 min read

The following is one of eight briefs commissioned for the 16th annual Brookings Blum Roundtable, “2020 and beyond: Maintaining the bipartisan narrative on US global development.”

On March 14, 2019, Tropical Cyclone Idai struck the southeast coast of Mozambique. The U.N. High Commissioner for Refugees reported that 1.85 million people needed assistance. 146,000 people were internally displaced, and Mozambique scrambled to house them in 155 temporary sites. 1 The cyclone and subsequent flooding damaged 100,000 homes, destroyed 1 million acres of crops, and demolished $1 billion worth of infrastructure. 2

One historic storm in one place over the course of one day. While Cyclone Idai was the worst storm in Mozambique’s history, the world is looking towards a future where these “unprecedented” storms are commonplace. This global challenge has and will continue to create a multitude of critical issues that the international community must confront, including:

Large-scale human migration due to resource scarcity, increased frequency of extreme weather events, and other factors, particularly in the developing countries in the earth’s low latitudinal band
Intensifying intra- and inter-state competition for food, water, and other resources, particularly in the Middle East and North Africa
Increased frequency and severity of disease outbreaks
Increased U.S. border stress due to the severe effects of climate change in parts of Central America

All of these challenges are serious, but the scope and scale of human migration due to climate change will test the limits of national and global governance as well as international cooperation.

The migration-climate nexus is real, but more scrutiny and action are required

In 2018, the World Bank estimated that three regions (Latin America, sub-Saharan Africa, and Southeast Asia) will generate 143 million more climate migrants by 2050. 3 In 2017, 68.5 million people were forcibly displaced, more than at any point in human history. While it is difficult to estimate, approximately one-third of these (22.5 million 4 to 24 million 5 people) were forced to move by “sudden onset” weather events—flooding, forest fires after droughts, and intensified storms. While the remaining two-thirds of displacements are the results of other humanitarian crises, it is becoming obvious that climate change is contributing to so-called slow onset events such as desertification, sea-level rise, ocean acidification, air pollution, rain pattern shifts and loss of biodiversity. 6 This deterioration will exacerbate many humanitarian crises and may lead to more people being on the move.

Multilateral institutions, development agencies, and international law must do far more to thoroughly examine the challenges of climate change (early efforts, like the World Bank’s 2010 World Development Report on climate change, 7 had little uptake at a time when few thought a climate crisis was around the corner). Moreover, neither a multilateral strategy nor a legal framework exist to account for climate change as a driver of migration. Whether in terms of limited access to clean water, food scarcity, agricultural degradation, or violent conflict, 8 climate change will intensify these challenges and be a significant push factor in human migration patterns.

To date, there are only a few cases where climate change is the sole factor prompting migration. The clearest examples are in the Pacific Islands. The sea level is rising at a rate of 12 millimeters per year in the western Pacific and has already submerged eight islands. Two more are on the brink of disappearing, prompting a wave of migration to larger countries. 9 10 By 2100, it is estimated that 48 islands overall will be lost to the rising ocean. 11 In 2015, the Teitota family applied for refugee status in New Zealand, fleeing the disappearing island nation of Kiribati. 12 Their case, the first request for refuge explicitly attributed climate change, made it to the High Court of New Zealand but was ultimately dismissed. Islands in the Federated States of Micronesia have drastically reduced in size, washed down to an uninhabitable state, had their fresh water contaminated by the inflow of seawater, and disappeared in the past decade. 13 Despite their extreme vulnerability, the relatively small population (2.3 million people spread across 11 countries 14 ) and remote location of the Pacific Islands means that they garner little international action, for all the attention they receive in the media.

Although there are few instances of climate change as the sole factor in migration, climate change is widely recognized as a contributing and exacerbating factor in migration and in conflict.

In South Asia, increasing temperatures, sea level rise, more frequent cyclones, flooding of river systems fed by melting glaciers, and other extreme weather events are exacerbating current internal and international migration patterns. Additionally, rapid economic growth and urbanization are accelerating and magnifying the impact and drivers of climate change—the demand for energy is expected to grow 66 percent by 2040. 15 Compounding this, many of the expanding urban areas are located in low-lying coastal areas, already threatened by sea level rise. 16 The confluence of these factors leads the World Bank to predict that the collective South Asian economy (Bangladesh, Bhutan, India, the Maldives, Nepal, and Sri Lanka) will lose 1.8 percent of its annual GDP due to climate change by 2050. 17 The New York Times reports that the living conditions of 800 million people could seriously diminish. 18 Diminishing living conditions on this scale and intensity will prompt mass migration—possibly at an unprecedented level.

Northwest Africa is facing rising sea levels, drought, and desertification. These conditions will only add to the already substantial number of seasonal migrants and put added strain on the country of origin, as well as on destination countries and the routes migrants travel. The destabilizing effects of climate change should be of great concern to all those who seek security and stability in the region. Climate and security experts often cite the impacts of the extreme drought in Syria that preceded the 2011 civil war. 19 The security community also highlights the connection between climate change and terrorism—for instance, the decline of agricultural and pastoral livelihoods has been linked to the effectiveness of financial recruiting strategies by al-Qaida. 20

The intersection of climate change and migration requires new, nimble, and comprehensive solutions to the multidimensional challenges it creates. Accordingly, the signatories to the 2015 Paris Agreement on climate change requested that the Warsaw International Mechanism for Loss and Damage Associated with Climate Change (WIM) develop recommendations for addressing people displaced by climate change. 21 Similarly, The Global Compact for Safe, Orderly, and Regular Migration (adopted by 164 countries—not including the U.S.—in Marrakech in December 2018) called on countries to make plans to prevent the need for climate-caused relocation and support those forced to relocate. 22 However, these agreements are neither legally binding nor sufficiently developed to support climate migrants—particularly migrants from South Asia, Central America, Northwest Africa, and the Horn of Africa.

Time to envision legal recourse for climate refugees

As gradually worsening climate patterns and, even more so, severe weather events, prompt an increase in human mobility, people who choose to move will do so with little legal protection. The current system of international law is not equipped to protect climate migrants, as there are no legally binding agreements obliging countries to support climate migrants.

While climate migrants who flee unbearable conditions resemble refugees, the legal protections afforded to refugees do not extend to them. In the aftermath of World War II, the United Nations established a system to protect civilians who had been forced from their home countries by political violence. Today, there are almost 20.4 million officially designated refugees under the protection of the United Nations High Commission for Refugees (UNHCR)—however, there is an additional group of 21.5 million people 23 who flee their homes as a result of sudden onset weather hazards every year. 24

The UNHCR has thus far refused to grant these people refugee status, instead designating them as “environmental migrants,” in large part because it lacks the resources to address their needs. But with no organized effort to supervise the migrant population, these desperate individuals go where they can, not necessarily where they should. As their numbers grow, it will become increasingly difficult for the international community to ignore this challenge. As severe climate change displaces more people, the international community may be forced to either redefine “refugees” to include climate migrants or create a new legal category and accompanying institutional framework to protect climate migrants. However, opening that debate in the current political context would be fraught with difficulty. Currently, the nationalist, anti-immigrant, and xenophobic atmosphere in Europe and the U.S. would most likely lead to limiting refugee protections rather than expanding them.

The SDGs can help, but not without an update to the US response

While there are no legally binding international regimes that protect climate migrants, there are voluntary compacts that could be used to support them. Most notably, 193 countries adopted the 2030 Sustainable Development Goals (SDGs), which address both migration and climate change.

Several of the 169 targets established by the SDGs lay out general goals that could be used to protect climate migrants. SDG 13 on climate action outlines several targets that address the climate crisis:

13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries
13.2: Integrate climate change measures into national policies, strategies, and planning
13.3: Improve education, awareness-raising and human and institutional capacity on climate change mitigation, adaptation, impact reduction, and early warning.

To meet these goals, extensive bilateral and multilateral development assistance will be needed. The U.S. must create a strategic approach to focus development assistance and multilateral organizations on those targets—particularly to create resilient societies that can keep people in their communities.

Although the SDGs do not explicitly link climate change and migration, SDG target 10.7 calls for signatories to “facilitate orderly, safe, and responsible migration of people, including through implementation of planned and well-managed policies.” Again, the United States should channel multilateral development assistance to support the implementation of this target.

The scale and scope of climate change demand dynamic and comprehensive solutions. The U.S. must address climate stress on vulnerable populations specifically, rather than funneling more money into existing programs that operate on the periphery of the growing crisis.

U.S. development agencies and international development financial institutions need to redirect their development assistance to incorporate today’s unfolding climate crisis. Significantly more resources will need to be channeled to the new U.S. International Development Finance Corporation (USDFC), USAID, the Green Climate Fund, UNHCR, as well as to other critical international bodies, in particular those that make up the International Red Cross and Red Crescent organizations.

The Obama administration undertook myriad efforts to update the institutions that can address climate. Several of President Obama’s executive orders, particularly Executive Order 13677, which required incorporating climate resilience into decisionmaking on development assistance, took on the climate crisis. For the first time in the Department of Defense’s history, the 2010 Quadrennial Defense Review (QDR) recognized climate change as a “threat multiplier,” with the potential to exacerbate current challenges. 25

While the current administration has deemphasized or opposed climate-friendly approaches, the current security implications of the migration crisis might prompt a re-examination of those policies. There should be bipartisan support, particularly in the security community, for reducing the conditions that accelerate international migration.

The case for scaling up US action to confront the climate crisis

A variety of medium-term investments (five to 10 years) could create more resilience to the effects of climate change. For example, the climate change factors that push migration in Northwest Africa could—at least in part—be addressed by supporting irrigation infrastructure, providing food supplies, fostering regional water cooperation, and supporting livelihood security. 26

Dedicating greater resources to mitigate climate migration is also part of an effective solution. Research is needed to determine the best way to improve the migratory process itself—be it increasing migration monitors, providing safer modes of transport, and consolidating and expanding destination country integration resources.

This discussion is not new: In 2010, Center for American Progress staff were part of a task force that suggested a “Unified Security Budget” for the United States, to address complex crisis scenarios that transcend the traditional division of labor among defense, diplomacy, and development. 27 The need for longer-term, more calculated assessment strategies and investments has only increased over the past decade. The Pentagon already supports a variety of operational missions that respond to sudden onset climate disasters. The Navy, in particular, serves at the emergency hotline for international extreme weather events and mobilized to support the Haitian people after the 2010 earthquake, the Filipino people after the 2013 typhoon, and the Nepalis after the 2015 earthquake.

Alternatively, creating a single dedicated fund (by drawing funds from Operations and Maintenance, Research and Development, and the Refugee Assistance Fund) would allow the United States to streamline and refine its support strategies, address the effects of climate change directly, and rebuild its reputation abroad. Such a dedicated fund should try to emulate and partner with the United Kingdom’s Department for International Development (DFID), Germany’s Society for International Cooperation (GIZ), and Japan’s International Cooperation Agency (JICA). American seed funding in this area could lead to major investments of allies and partners—and in cooperation with the development agencies of these countries can mobilize massive resources at the scale required to confront the global climate crisis.

The strategies to address climate migrants presented here are far reaching, but this crisis will only intensify, and our response to it will define international relations in the 21st century.

The Great Climate Migration Has Begun

By Abrahm Lustgarten July 23, 2020

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Today, 1% of the world is a barely livable hot zone.

By 2070, that portion could go up to 19%.

Billions of people call this land home.

Where will they go?

The Great Climate Migration By Abrahm Lustgarten | Photographs by Meridith Kohut

Early in 2019, a year before the world shut its borders completely, Jorge A. knew he had to get out of Guatemala. The land was turning against him. For five years, it almost never rained. Then it did rain, and Jorge rushed his last seeds into the ground. The corn sprouted into healthy green stalks, and there was hope — until, without warning, the river flooded. Jorge waded chest-deep into his fields searching in vain for cobs he could still eat. Soon he made a last desperate bet, signing away the tin-roof hut where he lived with his wife and three children against a $1,500 advance in okra seed. But after the flood, the rain stopped again, and everything died. Jorge knew then that if he didn’t get out of Guatemala, his family might die, too.

This article, the first in a series on global climate migration, is a partnership between ProPublica and The New York Times Magazine, with support from the Pulitzer Center. Read Part 2 and Part 3 , and more about the data project that underlies the reporting.

Even as hundreds of thousands of Guatemalans fled north toward the United States in recent years, in Jorge’s region — a state called Alta Verapaz, where precipitous mountains covered in coffee plantations and dense, dry forest give way to broader gentle valleys — the residents have largely stayed. Now, though, under a relentless confluence of drought, flood, bankruptcy and starvation, they, too, have begun to leave. Almost everyone here experiences some degree of uncertainty about where their next meal will come from. Half the children are chronically hungry, and many are short for their age, with weak bones and bloated bellies. Their families are all facing the same excruciating decision that confronted Jorge.

The odd weather phenomenon that many blame for the suffering here — the drought and sudden storm pattern known as El Niño — is expected to become more frequent as the planet warms. Many semiarid parts of Guatemala will soon be more like a desert. Rainfall is expected to decrease by 60 percent in some parts of the country, and the amount of water replenishing streams and keeping soil moist will drop by as much as 83 percent. Researchers project that by 2070, yields of some staple crops in the state where Jorge lives will decline by nearly a third.

Scientists have learned to project such changes around the world with surprising precision, but — until recently — little has been known about the human consequences of those changes. As their land fails them, hundreds of millions of people from Central America to Sudan to the Mekong Delta will be forced to choose between flight or death. The result will almost certainly be the greatest wave of global migration the world has seen.

In March, Jorge and his 7-year-old son each packed a pair of pants, three T-shirts, underwear and a toothbrush into a single thin black nylon sack with a drawstring. Jorge’s father had pawned his last four goats for $2,000 to help pay for their transit, another loan the family would have to repay at 100 percent interest. The coyote called at 10 p.m. — they would go that night. They had no idea then where they would wind up, or what they would do when they got there.

From decision to departure, it was three days. And then they were gone.

For most of human history, people have lived within a surprisingly narrow range of temperatures, in the places where the climate supported abundant food production. But as the planet warms, that band is suddenly shifting north. According to a pathbreaking recent study in the journal Proceedings of the National Academy of Sciences, the planet could see a greater temperature increase in the next 50 years than it did in the last 6,000 years combined. By 2070, the kind of extremely hot zones, like in the Sahara, that now cover less than 1 percent of the earth’s land surface could cover nearly a fifth of the land, potentially placing one of every three people alive outside the climate niche where humans have thrived for thousands of years. Many will dig in, suffering through heat, hunger and political chaos, but others will be forced to move on. A 2017 study in Science Advances found that by 2100, temperatures could rise to the point that just going outside for a few hours in some places, including parts of India and Eastern China, “will result in death even for the fittest of humans.”

People are already beginning to flee. In Southeast Asia, where increasingly unpredictable monsoon rainfall and drought have made farming more difficult, the World Bank points to more than eight million people who have moved toward the Middle East, Europe and North America. In the African Sahel, millions of rural people have been streaming toward the coasts and the cities amid drought and widespread crop failures. Should the flight away from hot climates reach the scale that current research suggests is likely, it will amount to a vast remapping of the world’s populations.

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Migration can bring great opportunity not just to migrants but also to the places they go. As the United States and other parts of the global North face a demographic decline, for instance, an injection of new people into an aging work force could be to everyone’s benefit. But securing these benefits starts with a choice: Northern nations can relieve pressures on the fastest-warming countries by allowing more migrants to move north across their borders, or they can seal themselves off, trapping hundreds of millions of people in places that are increasingly unlivable. The best outcome requires not only good will and the careful management of turbulent political forces; without preparation and planning, the sweeping scale of change could prove wildly destabilizing. The United Nations and others warn that in the worst case, the governments of the nations most affected by climate change could topple as whole regions devolve into war.

The stark policy choices are already becoming apparent. As refugees stream out of the Middle East and North Africa into Europe and from Central America into the United States, an anti-immigrant backlash has propelled nationalist governments into power around the world. The alternative, driven by a better understanding of how and when people will move, is governments that are actively preparing, both materially and politically, for the greater changes to come.

Projected percentage decrease by 2070 in the yield of the rice crop in Alta Verapaz, Guatemala:

Last summer, I went to Central America to learn how people like Jorge will respond to changes in their climates. I followed the decisions of people in rural Guatemala and their routes to the region’s biggest cities, then north through Mexico to Texas. I found an astonishing need for food and witnessed the ways competition and poverty among the displaced broke down cultural and moral boundaries. But the picture on the ground is scattered. To better understand the forces and scale of climate migration over a broader area, The New York Times Magazine and ProPublica joined with the Pulitzer Center in an effort to model, for the first time, how people will move across borders.

We focused on changes in Central America and used climate and economic-development data to examine a range of scenarios. Our model projects that migration will rise every year regardless of climate, but that the amount of migration increases substantially as the climate changes. In the most extreme climate scenarios, more than 30 million migrants would head toward the U.S. border over the course of the next 30 years.

Migrants move for many reasons, of course. The model helps us see which migrants are driven primarily by climate, finding that they would make up as much as 5 percent of the total. If governments take modest action to reduce climate emissions, about 680,000 climate migrants might move from Central America and Mexico to the United States between now and 2050. If emissions continue unabated, leading to more extreme warming, that number jumps to more than a million people. (None of these figures include undocumented immigrants, whose numbers could be twice as high.)

The model shows that the political responses to both climate change and migration can lead to drastically different futures.

In one scenario, globalization — with its relatively open borders — continues.

As the climate changes, drought and food insecurity drive rural residents in Mexico and Central America out of the countryside.

Millions seek relief, first in big cities, spurring a rapid and increasingly overwhelming urbanization.

Then they move farther north, pushing the largest number of migrants toward the United States. The projected number of migrants arriving from Central America and Mexico rises to 1.5 million a year by 2050, from about 700,000 a year in 2025.

We modeled another scenario in which the United States hardens its borders. People are turned back, and economic growth in Central America slows, as does urbanization.

In this case, Central America’s population surges, and the rural hollowing reverses as the birthrate rises, poverty deepens and hunger grows — all with hotter weather and less water.

That version of the world leaves tens of millions of people more desperate and with fewer options. Misery reigns, and large populations become trapped.

As with much modeling work, the point here is not to provide concrete numerical predictions so much as it is to provide glimpses into possible futures. Human movement is notoriously hard to model, and as many climate researchers have noted, it is important not to add a false precision to the political battles that inevitably surround any discussion of migration. But our model offers something far more potentially valuable to policymakers: a detailed look at the staggering human suffering that will be inflicted if countries shut their doors.

In recent months, the coronavirus pandemic has offered a test run on whether humanity has the capacity to avert a predictable — and predicted — catastrophe. Some countries have fared better. But the United States has failed. The climate crisis will test the developed world again, on a larger scale, with higher stakes. The only way to mitigate the most destabilizing aspects of mass migration is to prepare for it, and preparation demands a sharper imagining of where people are likely to go, and when.

I. A Different Kind of Climate Model

In November 2007, Alan B. Krueger, a labor economist known for his statistical work on inequality, walked into the Princeton University offices of Michael Oppenheimer, a leading climate geoscientist, and asked him whether anyone had ever tried to quantify how and where climate change would cause people to move.

Earlier that year, Oppenheimer helped write the U.N. Intergovernmental Panel on Climate Change report that, for the first time, explored in depth how climate disruption might uproot large segments of the global population. But as groundbreaking as the report was — the U.N. was recognized for its work with a Nobel Peace Prize — the academic disciplines whose work it synthesized were largely siloed from one another. Demographers, agronomists and economists were all doing their work on climate change in isolation, but understanding the question of migration would have to include all of them.

Together, Oppenheimer and Krueger, who died in 2019, began to chip away at the question, asking whether tools typically used by economists might yield insight into the environment’s effects on people’s decision to migrate. They began to examine the statistical relationships — say, between census data and crop yields and historical weather patterns — in Mexico to try to understand how farmers there respond to drought. The data helped them create a mathematical measure of farmers’ sensitivity to environmental change — a factor that Krueger could use the same way he might evaluate fiscal policies, but to model future migration.

Their study, published in 2010 in Proceedings of the National Academy of Sciences, found that Mexican migration to the United States pulsed upward during periods of drought and projected that by 2080, climate change there could drive 6.7 million more people toward the Southern U.S. border. “It was,” Oppenheimer said, “one of the first applications of econometric modeling to the climate-migration problem.”

The modeling was a start. But it was hyperlocal instead of global, and it left open huge questions: how cultural differences might change outcomes, for example, or how population shifts might occur across larger regions. It was also controversial, igniting a backlash among climate-change skeptics, who attacked the modeling effort as “guesswork” built on “tenuous assumptions” and argued that a model couldn’t untangle the effect of climate change from all the other complex influences that determine human decision-making and migration. That argument eventually found some traction with migration researchers, many of whom remain reluctant to model precise migration figures.

But to Oppenheimer and Krueger, the risks of putting a specific shape to this well established but amorphous threat seemed worth taking. In the early 1970s, after all, many researchers had made a similar argument against using computer models to forecast climate change, arguing that scientists shouldn’t traffic in predictions. Others ignored that advice, producing some of the earliest projections about the dire impact of climate change, and with them some of the earliest opportunities to try to steer away from that fate. Trying to project the consequences of climate-driven migration, to Oppenheimer, called for similarly provocative efforts. “If others have better ideas for estimating how climate change affects migration,” he wrote in 2010, “they should publish them.”

Since then, Oppenheimer’s approach has become common. Dozens more studies have applied econometric modeling to climate-related problems, seizing on troves of data to better understand how environmental change and conflict each lead to migration and clarify how the cycle works. Climate is rarely the main cause of migration, the studies have generally found, but it is almost always an exacerbating one.

As they have looked more closely, migration researchers have found climate’s subtle fingerprints almost everywhere. Drought helped push many Syrians into cities before the war, worsening tensions and leading to rising discontent; crop losses led to unemployment that stoked Arab Spring uprisings in Egypt and Libya ; Brexit, even, was arguably a ripple effect of the influx of migrants brought to Europe by the wars that followed. And all those effects were bound up with the movement of just two million people. As the mechanisms of climate migration have come into sharper focus — food scarcity, water scarcity and heat — the latent potential for large-scale movement comes to seem astronomically larger.

North Africa’s Sahel provides an example. In the nine countries stretching across the continent from Mauritania to Sudan, extraordinary population growth and steep environmental decline are on a collision course. Past droughts, most likely caused by climate change, have already killed more than 100,000 people there. And the region — with more than 150 million people and growing — is threatened by rapid desertification, even more severe water shortages and deforestation. Today researchers at the United Nations estimate that some 65 percent of farmable lands have already been degraded. “My deep fear,” said Solomon Hsiang, a climate researcher and economist at the University of California, Berkeley, is that Africa’s transition into a post-climate-change civilization “leads to a constant outpouring of people.”

The story is similar in South Asia, where nearly one-fourth of the global population lives. The World Bank projects that the region will soon have the highest prevalence of food insecurity in the world. While some 8.5 million people have fled already — resettling mostly in the Persian Gulf — 17 million to 36 million more people may soon be uprooted, the World Bank found. If past patterns are a measure, many will settle in India’s Ganges Valley; by the end of the century, heat waves and humidity will become so extreme there that people without air-conditioning will simply die.

If it is not drought and crop failures that force large numbers of people to flee, it will be the rising seas. We are now learning that climate scientists have been underestimating the future displacement from rising tides by a factor of three, with the likely toll being some 150 million globally. New projections show high tides subsuming much of Vietnam by 2050 — including most of the Mekong Delta, now home to 18 million people — as well as parts of China and Thailand, most of southern Iraq and nearly all of the Nile Delta, Egypt’s breadbasket. Many coastal regions of the United States are also at risk.

Through all the research, rough predictions have emerged about the scale of total global climate migration — they range from 50 million to 300 million people displaced — but the global data is limited, and uncertainty remained about how to apply patterns of behavior to specific people in specific places. Now, though, new research on both fronts has created an opportunity to improve the models tremendously. A few years ago, climate geographers from Columbia University and the City University of New York began working with the World Bank to build a next-generation tool to establish plausible migration scenarios for the future. The idea was to build on the Oppenheimer-style measure of response to the environment with other methods of analysis, including a “gravity” model, which assesses the relative attractiveness of destinations with the hope of mathematically anticipating where migrants might end up. The resulting report, published in early 2018, involved six European and American institutions and took nearly two years to complete.

The bank’s work targeted climate hot spots in sub-Saharan Africa, South Asia and Latin America, focusing not on the emergency displacement of people from natural disasters but on their premeditated responses to what researchers call “slow-onset” shifts in the environment. They determined that as climate change progressed in just these three regions alone, as many as 143 million people would be displaced within their own borders, moving mostly from rural areas to nearby towns and cities. The study, though, wasn’t fine-tuned to specific climatic changes like declining groundwater. And it didn’t even try to address the elephant in the room: How would the climate push people to migrate across international borders?

In early 2019, The Times Magazine and ProPublica, with support from the Pulitzer Center, hired an author of the World Bank report — Bryan Jones, a geographer at Baruch College — to add layers of environmental data to its model, making it even more sensitive to climatic change and expanding its reach. Our goal was to pick up where the World Bank researchers left off, in order to model, for the first time, how people would move between countries, especially from Central America and Mexico toward the United States.

First we gathered existing data sets — on political stability, agricultural productivity, food stress, water availability, social connections, weather and much more — in order to approximate the kaleidoscopic complexity of human decision-making.

Then we started asking questions: If crop yields continue to decline because of drought, for instance, and people are forced to respond by moving, as they have in the past, can we see where they will go and see what new conditions that might introduce? It’s very difficult to model how individual people think or to answer these questions using individual data points — often the data simply doesn’t exist. Instead of guessing what Jorge A. will do and then multiplying that decision by the number of people in similar circumstances, the model looks across entire populations, averaging out trends in community decision-making based on established patterns, then seeing how those trends play out in different scenarios.

Projected percentage of city dwellers who will live in slums by 2030:

In all, we fed more than 10 billion data points into our model. Then we tested the relationships in the model retroactively, checking where historical cause and effect could be empirically supported, to see if the model’s projections about the past matches what really happened. Once the model was built and layered with both approaches — econometric and gravity — we looked at how people moved as global carbon concentrations increased in five different scenarios, which imagine various combinations of growth, trade and border control, among other factors. (These scenarios have become standard among climate scientists and economists in modeling different pathways of global socioeconomic development.)

Only a supercomputer could efficiently process the work in its entirety; estimating migration from Central America and Mexico in one case required uploading our query to a federal mainframe housed in a building the size of a small college campus outside Cheyenne, Wyo., run by the National Center for Atmospheric Research, where even there it took four days for the machine to calculate its answers. (A more detailed description of the data project can be found at propublica.org/migration-methodology .)

The results are built around a number of assumptions about the relationships between real-world developments that haven’t all been scientifically validated. The model also assumes that complex relationships — say, how drought and political stability relate to each other — remain consistent and linear over time (when in reality we know the relationships will change, but not how). Many people will also be trapped by their circumstances, too poor or vulnerable to move, and the models have a difficult time accounting for them.

All this means that our model is far from definitive. But every one of the scenarios it produces points to a future in which climate change, currently a subtle disrupting influence, becomes a source of major disruption, increasingly driving the displacement of vast populations.

II. How Climate Moves People

Delmira de Jesús Cortez Barrera moved to the outskirts of San Salvador six years ago, after her life in the rural western edge of El Salvador — just 90 miles from Jorge A.’s village in Guatemala — collapsed. Now she sells pupusas on a block not far from where teenagers stand guard for the Mara Salvatrucha gang. When we met last summer, she was working six days a week, earning $7 a day, or less than $200 a month. She relied on the kindness of her boss, who gave her some free meals at work. But everything else for her and her infant son she had to provide herself. Cortez commuted before dawn from San Marcos, where she lived with her sister in a cheap room off a pedestrian alleyway. But her apartment still cost $65 each month. And she sent $75 home to her parents each month — enough for beans and cheese to feed the two daughters she left with them. “We’re going backward,” she said.

Her story — that of an uneducated, unskilled woman from farm roots who can’t find high-paying work in the city and falls deeper into poverty — is a familiar one, the classic pattern of in-country migration all around the world. San Salvador, meanwhile, has become notorious as one of the most dangerous cities in the world, a capital in which gangs have long controlled everything from the majestic colonial streets of its downtown squares to the offices of the politicians who reside in them. It is against this backdrop of war, violence, hurricanes and poverty that one in six of El Salvador’s citizens have fled for the United States over the course of the last few decades, with some 90,000 Salvadorans apprehended at the U.S. border in 2019 alone.

Cortez was born about a mile from the Guatemalan border, in El Paste, a small town nestled on the side of a volcano. Her family were jornaleros — day laborers who farmed on the big maize and bean plantations in the area — and they rented a two-room mud-walled hut with a dirt floor, raising nine children there. Around 2012, a coffee blight worsened by climate change virtually wiped out El Salvador’s crop, slashing harvests by 70 percent. Then drought and unpredictable storms led to what a U.N.-affiliated food-security organization describes as “a progressive deterioration” of Salvadorans’ livelihoods.

That’s when Cortez decided to leave. She married and found work as a brick maker at a factory in the nearby city of Ahuachapán. But the gangs found easy prey in vulnerable farmers and spread into the Salvadoran countryside and the outlying cities, where they made a living by extorting local shopkeepers. Here we can see how climate change can act as what Defense Department officials sometimes refer to as a “threat multiplier.” For Cortez, the threat could not have been more dire. After two years in Ahuachapán, a gang-connected hit man knocked on Cortez’s door and took her husband, whose ex-girlfriend was a gang member, executing him in broad daylight a block away.

In other times, Cortez might have gone back home. But there was no work in El Paste, and no water. So she sent her children there and went to San Salvador instead.

For all the ways in which human migration is hard to predict, one trend is clear: Around the world, as people run short of food and abandon farms, they gravitate toward cities, which quickly grow overcrowded. It’s in these cities, where waves of new people stretch infrastructure, resources and services to their limits, that migration researchers warn that the most severe strains on society will unfold. Food has to be imported — stretching reliance on already-struggling farms and increasing its cost. People will congregate in slums, with little water or electricity, where they are more vulnerable to flooding or other disasters. The slums fuel extremism and chaos.

It is a shift that is already well underway, which is why the World Bank has raised concerns about the mind-boggling influx of people into East African cities like Addis Ababa, in Ethiopia, where the population has doubled since 2000 and is expected to nearly double again by 2035. In Mexico, the World Bank estimates, as many as 1.7 million people may migrate away from the hottest and driest regions, many of them winding up in Mexico City.

But like so much of the rest of the climate story, the urbanization trend is also just the beginning. Right now a little more than half of the planet’s population lives in urban areas, but by the middle of the century, the World Bank estimates, 67 percent will. In just a decade, four out of every 10 urban residents — two billion people around the world — will live in slums. The International Committee of the Red Cross warns that 96 percent of future urban growth will happen in some of the world’s most fragile cities, which already face a heightened risk of conflict and have governments that are least capable of dealing with it. Some cities will be unable to sustain the influx. In the case of Addis Ababa, the World Bank suggests that in the second half of the century, many of the people who fled there will be forced to move again, leaving that city as local agriculture around it dries up.

Percentage of El Salvador’s 6.4 million residents who currently lack a reliable source of food:

Our modeling effort is premised on the notion that in these cities as they exist now, we can see the seeds of their future growth. Relationships between quality-of-life factors like household income in specific neighborhoods, education levels, employment rates and so forth — and how each of those changed in response to climate — would reveal patterns that could be projected into the future. As moisture raises the grain in a slab of wood, the information just needed to be elicited.

Under every scientific forecast for global climate change, El Salvador gets hotter and drier, and our model was in accord with what other researchers said was likely: San Salvador will continue to grow as a result, putting still more people in its dense outer rings. What happens in its farm country, though, is more dependent on which climate and development policies governments to the north choose to deploy in dealing with the warming planet. High emissions, with few global policy changes and relatively open borders, will drive rural El Salvador — just like rural Guatemala — to empty out, even as its cities grow.

Should the United States and other wealthy countries change the trajectory of global policy, though — by, say, investing in climate mitigation efforts at home but also hardening their borders — they would trigger a complex cascade of repercussions farther south, according to the model. Central American and Mexican cities continue to grow, albeit less quickly, but their overall wealth and development slows drastically, most likely concentrating poverty further. Far more people also remain in the countryside for lack of opportunity, becoming trapped and more desperate than ever.

People move to cities because they can seem like a refuge, offering the facade of order — tall buildings and government presence — and the mirage of wealth. I met several men who left their farm fields seeking extremely dangerous work as security guards in San Salvador and Guatemala City. I met a 10-year-old boy washing car windows at a stoplight, convinced that the coins in his jar would help buy back his parents’ farmland. Cities offer choices, and a sense that you can control your destiny.

These same cities, though, can just as easily become traps, as the challenges that go along with rapid urbanization quickly pile up. Since 2000, San Salvador’s population has ballooned by more than a third as it has absorbed migrants from the rural areas, even as tens of thousands of people continue to leave the country and migrate north. By midcentury, the U.N. estimates that El Salvador — which has 6.4 million people and is the most densely populated country in Central America — will be 86 percent urban.

Our models show that much of the growth will be concentrated in the city’s slumlike suburbs, places like San Marcos, where people live in thousands of ramshackle structures, many without electricity or fresh water. In these places, even before the pandemic and its fallout, good jobs were difficult to find, poverty was deepening and crime was increasing. Domestic abuse has also been rising, and declining sanitary conditions threaten more disease. As society weakens, the gangs — whose members outnumber the police in parts of El Salvador by an estimated three to one — extort and recruit. They have made San Salvador’s murder rate one of the highest in the world.

Cortez hoped to escape the violence, but she couldn’t. The gangs run through her apartment block, stealing televisions and collecting protection payments. She had recently witnessed a murder inside a medical clinic where she was delivering food. The lack of security, the lack of affordable housing, the lack of child care, the lack of sustenance — all influence the evolution of complex urban systems under migratory pressure, and our model considers such stresses by incorporating data on crime, governance and health care. They are signposts for what is to come.

A week before our meeting last year, Cortez had resolved to make the trip to the United States at almost any cost. For months she had “felt like going far away,” but moving home was out of the question. “The climate has changed, and it has provoked us,” she said, adding that it had scarcely rained in three years. “My dad, last year, he just gave up.”

Cortez recounted what she did next. As her boss dropped potato pupusas into the smoking fryer, Cortez turned to her and made an unimaginable request: Would she take Cortez’s baby? It was the only way to save the child, Cortez said. She promised to send money from the United States, but the older woman said no — she couldn’t imagine being able to care for the infant.

Today San Salvador is shut down by the coronavirus pandemic, and Cortez is cooped up inside her apartment in San Marcos. She hasn’t worked in three months and is unable to see her daughters in El Paste. She was allowed a forbearance on rent during the country’s official lockdown, but that has come to an end. She remains convinced that the United States is her only salvation — border walls be damned. She’ll leave, she said, “the first chance I get.”

Most would-be migrants don’t want to move away from home. Instead, they’ll make incremental adjustments to minimize change, first moving to a larger town or a city. It’s only when those places fail them that they tend to cross borders, taking on ever riskier journeys, in what researchers call “stepwise migration.” Leaving a village for the city is hard enough, but crossing into a foreign land — vulnerable to both its politics and its own social turmoil — is an entirely different trial.

Seven miles from the Suchiate River, which marks Guatemala’s border with Mexico, sits Siglo XXI, one of Mexico’s largest immigration detention centers, a squat concrete compound with 30-foot walls, barred windows and a punishment cell. In early 2019, the 960-bed facility was largely empty, as Mexico welcomed passing migrants instead of detaining them. But by March, as the United States increased pressure to stop Central Americans from reaching its borders, Mexico had begun to detain migrants who crossed into its territory, packing almost 2,000 people inside this center near the city of Tapachula. Detainees slept on mattresses thrown down in the white-tiled hallways, waited in lines to use toilets overflowing with feces and crammed shoulder to shoulder for hours to get a meal of canned meat spooned onto a metal tray.

Projected decrease in percentage of annual rainfall by 2070 in many parts of Guatemala:

On April 25, imprisoned migrants stormed the stairway leading to a fortified security platform in the center’s main hall, overpowering the guards and then unlocking the main gates. More than 1,000 Guatemalans, Cubans, Salvadorans, Haitians and others streamed into the Tapachula night.

I arrived in Tapachula five weeks after the breakout to find a city cracking in the crucible of migration. Just months earlier, passing migrants on Mexico’s southern border were offered rides and tortas and medicine from a sympathetic Mexican public. Now migrant families were being hunted down in the countryside by armed national-guard units, as if they were enemy soldiers.

Mexico has not always welcomed migrants, but President Andrés Manuel López Obrador was trying to make his country a model for increasingly open borders. This idealistic effort was also pragmatic: It was meant to show the world an alternative to the belligerent wall-building xenophobia he saw gathering momentum in the United States. More open borders, combined with strategic foreign aid and help with human rights to keep Central American migrants from leaving their homes in the first place, would lead to a better outcome for all nations. “I want to tell them they can count on us,” López Obrador had declared, promising the migrants work permits and temporary jobs.

The architects of Mexico’s policies assumed that its citizens had the patience and the capacity to absorb — economically, environmentally and socially — such an influx of people. But they failed to anticipate how President Trump would hold their economy hostage to press his own anti-immigrant crackdown, and they were caught off-guard by how the burdens brought by the immigration traffic weighed on Mexico’s own people.

In the six months after López Obrador took office in December 2018, some 420,000 people entered Mexico without documentation, according to Mexico’s National Migration Institute. Many floated across the Suchiate on boards tied atop large inner tubes, paying guides a couple of dollars for passage. In Ciudad Hidalgo, a border town outside Tapachula, migrants camped in the square and fought in the streets. In a late-night interview in his cinder-block office, under the glare of fluorescent lights, the town’s director of public security, Luis Martínez López, rattled off statistics about their impact: Armed robberies jumped 45 percent; murders increased 15 percent.

Whether the crimes were truly attributable to the migrants was a matter of significant debate, but the perception that they were fueled a rising impatience. That March, Martínez told me, a confrontation between a crowd of about 400 migrants and the local police turned rowdy, and the migrants tied up five officers in the center of town. No one was hurt, but the incident stoked locals’ concern that things were getting out of control. “We used to open doors for them like brothers and feed them,” said Martínez, who has since left his government job. “I was disappointed and angry.”

In Tapachula, a much larger city, tourism and commerce began to suffer. Whole families of migrants huddled in downtown doorways overnight, crowding sidewalks and sleeping on thin, oil-stained sheets of cardboard. Hotels — normally almost sold out in December — were less than 65 percent full as visitors stayed away, fearful of crime. Clinics ran short of medication. The impact came at a vulnerable moment: While many northern Mexican states enjoyed economic growth of 3 to 11 percent in 2018, Chiapas — its southernmost state — had a 3 percent drop in its gross domestic product. “They are overwhelmed,” said the Rev. César Cañaveral Pérez, who earned a Ph.D. in the theology of human mobility in Rome and now runs Tapachula’s largest Catholic migrant shelter.

Models can’t say much about the cultural strain that might result from a climate influx; there is no data on anger or prejudice. What they do say is that over the next two decades, if climate emissions continue as they are, the population in southern Mexico will grow sharply.

At the same time, Mexico has its own serious climate concerns and will most likely see its own climate exodus. One in six Mexicans now rely on farming for their livelihood, and close to half the population lives in poverty. Studies estimate that with climate change, water availability per capita could decrease by as much as 88 percent in places, and crop yields in coastal regions may drop by a third. If that change does indeed push out a wave of Mexican migrants, many of them will most likely come from Chiapas.

Yet a net increase in population at the same time — which is what our models assume — suggests that even as one million or so climate migrants make it to the U.S. border, many more Central Americans will become trapped in protracted transit, unable to move forward or backward in their journey, remaining in southern Mexico and making its current stresses far worse.

Percentage of future urban growth that, according to the International Committee of the Red Cross, is likely to take place in some of the world’s most fragile cities, where risk of social unrest is high:

Already, by late last year, the Mexican government’s ill-planned policies had begun to unravel into something more insidious: rising resentment and hate. Now that the coronavirus pandemic has effectively sealed borders, those sentiments risk bubbling over. Migrants, with nowhere to go and no shelters able to take them in, roam the streets, unable to socially distance and lacking even basic sanitation.

It has angered many Mexican citizens, who have begun to describe the migrants as economic parasites and question foreign aid aimed at helping people cope with the drought in places where Jorge A. and Cortez come from.

“How dare AMLO give $30 million to El Salvador when we have no services here?” asked Javier Ovilla Estrada, a community-group leader in the southern border town Ciudad Hidalgo, referring to López Obrador’s participation in a multibillion-dollar development plan with Guatemala, Honduras and El Salvador. Ovilla has become a strident defender of a new Mexico-first movement, organizing thousands to march against immigrants. Months before the coronavirus spread, we met in the sterile dining room of a Chinese restaurant that he frequents in Ciudad Hidalgo, and he echoed the same anti-immigrant sentiments rising in the U.S. and Europe.

The migrants “don’t love this country,” he said. He points to anti-immigrant Facebook groups spreading rumors that migrants stole ballots and rigged the Mexican presidential election, that they murder with impunity and run brothels. He’s not the first to tell me that the migrants traffic in disease — that Suchiate will soon be overwhelmed by Ebola. “They should close the borders once and for all,” he said. If they don’t, he warns, the country will sink further into lawlessness and conflict. “We’re going to go out into the streets to defend our homes and our families.”

One afternoon last summer, I sat on a black pleather couch in a borrowed airport-security office at the Tapachula airfield to talk with Francisco Garduño Yáñez, Mexico’s new commissioner for immigration. Garduño had abruptly succeeded a man named Tonatiuh Guillén López, a strong proponent of more open borders, whom I’d been trying to reach for weeks to ask how Mexico had strayed so far from the mission he laid out for it.

But in between, Trump had, as another senior government official told me, “held a gun to Mexico’s head,” demanding a crackdown at the Guatemalan border under threat of a 25 percent tariff on trade. Such a tax could break the back of Mexico’s economy overnight, and so López Obrador’s government immediately agreed to dispatch a new militarized force to the border. Guillén resigned as a result, four days before I hoped to meet him.

Number of people projected to be displaced from their homes by rising sea levels alone by 2050:

Garduño, a cheerful man with short graying hair, a broad smile and a ceaseless handshake, had been on the job for less than 36 hours. He had flown to Tapachula because another riot had broken out in one of the city’s smaller fortified detention centers, and a starving Haitian refugee was filmed by news crews there, begging for help for her and her young son. I wanted to know how it had come to this — from signing an international humanitarian migrant bill of rights to a mother lying with her face pressed to the ground in a detention center begging for food, in the space of a few months. He demurred, laying blame at the feet of neoliberal economics, which he said had produced a “poverty factory” with no regional development policies to address it. It was the system — capitalism itself — that had abandoned human beings, not Mexico’s leaders. “We didn’t anticipate that the globalization of the economy, the globalization of the law … would have such a devastating effect,” Garduño told me.

It seemed telling that Garduño’s previous role had been as Mexico’s commissioner of federal prisons. Was this the start of a new, punitive Mexico? I asked him. Absolutely not, he replied. But Mexico was now pursuing a policy of “containment,” he said, rejecting the notion that his country was obligated to “receive a global migration.”

No policy, though, would be able to stop the forces — climate, increasingly, among them — that are pushing migrants from the south to breach Mexico’s borders, legally or illegally. So what happens when still more people — many millions more — float across the Suchiate River and land in Chiapas? Our model suggests that this is what is coming — that between now and 2050, nearly nine million migrants will head for Mexico’s southern border, more than 300,000 of them because of climate change alone.

Before leaving Mexico last summer, I went to Huixtla, a small town 25 miles west of Tapachula that, because it sat on the Bestia freight rail line used by migrants, had long been a waypoint on Mexico’s superhighway for Central Americans on their way north. Joining several local police officers as they headed out on patrol, I watched as our pickup truck’s red and blue lights reflected in the barred windows of squat cinder-block homes. Two officers stood in back, holding tight to the truck’s roll bars, black combat boots firmly planted in the cargo bed, as the driver, dodging mangy dogs, navigated the town’s slender alleyways.

The operations commander, a soft-spoken bureaucratic type named José Gozalo Rodríguez Méndez, sat in the front seat. I asked him if he thought Mexico could sustain the number of migrants who might soon come. He said Mexico would buckle. There is no money from the federal government, no staffing to address services, no housing, let alone shelter, no more good will. “We couldn’t do it.”

Rodríguez had already been tested. When the first caravan of thousands of migrants reached Huixtla in late 2018, throngs of tired, destitute people — many of them carrying children in their emaciated arms — packed the central square and spilled down the city’s side streets. Rodríguez and his wife went through their cupboards, gathering corn, fried beans and tortillas, and collected clothing outgrown by their children and hauled all of it to the town center, where church and civic groups had set up tents and bathrooms.

But as the caravans continued, he said, his good will began to disintegrate. “It’s like inviting somebody to your place for dinner,” he said. “You’ll invite them once, even twice. But will you invite them six times?” When the fourth caravan of migrants approached the city last March, Rodríguez told me, he stayed home.

In the center of town, the truck lurched to a stop amid a busy market, where stalls sell vegetables and toys under blue light filtered through plastic tarps overhead. A short way away, five men sheltered from the searing heat under the shade of a metal awning on the platform of a crumbling railway station, never repaired after Hurricane Stan 14 years earlier. Rodríguez peppered the group — two from Honduras, three from Guatemala — with questions. Together they said they had suffered the totality of misfortune that Central America offers: muggings, gang extortion and environmental disaster. Either they couldn’t grow food or the drought made it too expensive to buy.

“We can’t stand the hunger,” said one Honduran farmer, Jorge Reyes, his gaunt face dripping with sweat. At his feet was a gift from a shopkeeper: a plastic bag filled with a cut of raw meat, pooled in its own blood, flies circling around it in the heat. Reyes had nowhere to cook it. “If we are going to die anyway,” he said, “we might as well die trying to get to the United States.”

III. The Choice

Reyes had made his decision. Like Jorge A., Cortez and millions of others, he was going to the U.S. The next choice — how to respond and prepare for the migrants — ultimately falls to America’s elected leaders.

Over the course of 2019, El Paso, Texas, had endured a crush of people at its border crossings, peaking at more than 4,000 migrants in a single day, as the same caravans of Central Americans that had worn out their welcome in Tapachula made their way here. It put El Paso in a delicate spot, caught between the forces of politically charged anti-immigrant federal policy and its own deep roots as a diverse, largely Hispanic city whose identity was virtually inextricable from its close ties to Mexico. This surge, though, stretched the city’s capacity. When the migrants arrived, city officials argued over who should pay the tab for the emergency services, aid and housing, and in the end crossed their fingers and hoped the city’s active private charities would figure it out. Church groups rented thousands of hotel rooms across the city, delivered food, offered counseling and so on.

Conjoined to the Mexican city of Juárez, the El Paso area is the second-largest binational metroplex in the Western Hemisphere. It sits smack in the middle of the Chihuahuan Desert, a built-up oasis amid a barren and bleached-bright rocky landscape. Much of its daily work force commutes across the border, and Spanish is as common as English.

Downtown, new buildings are rising in a weary business district where boot shops and pawnshops compete amid boarded-up and barred storefronts. The only barriers between the American streets — home to more than 800,000 people — and their Juárez counterparts are the concrete viaduct of a mostly dry Rio Grande and a rusted steel border fence.

To some migrants, this place is Eden. But El Paso is also a place with oppressive heat and very little water, another front line in the climate crisis. Temperatures already top 90 degrees here for three months of the year, and by the end of the century it will be that hot one of every two days. The heat, according to researchers at the University of California, Berkeley, will drive deaths that soon outpace those from car crashes or opioid overdoses. Cooling costs — already a third of some residents’ budgets — will get pricier, and warming will drive down economic output by 8 percent, perhaps making El Paso just as unlivable as the places farther south.

In 2014, El Paso created a new city government position — chief resilience officer — aimed, in part, at folding climate concerns into its urban planning. Soon enough, the climate crisis in Guatemala — not just the one in El Paso — became one of the city’s top concerns. “I apologize if I’m off topic,” the resilience chief, Nicole Ferrini, told municipal leaders and other attendees at a water conference in Phoenix in 2019 as she raised the question of “massive amounts of climate refugees, and are we prepared as a community, as a society, to deal with that?”

Ferrini, an El Paso native, did her academic training as an architect. She worries that El Paso will struggle to adapt if its leadership, and the nation’s, continue to react to daily or yearly spikes rather than view the problem as a systematic one, destined to become steadily worse as the planet warms. She sees her own city as an object lesson in what U.N. officials and climate-migration scientists have been warning of: Without a decent plan for housing, feeding and employing a growing number of climate refugees, cities on the receiving end of migration can never confidently pilot their own economic future.

For the moment, the coronavirus pandemic has largely choked off legal crossings into El Paso, but that crisis will eventually fade. And when it does, El Paso will face the same enduring choice that all wealthier societies everywhere will eventually face: determining whether it is a society of walls or — in the vernacular of aid organizations working to fortify infrastructure and resilience to stem migration — one that builds wells.

Around the world, nations are choosing walls. Even before the pandemic, Hungary fenced off its boundary with Serbia, part of more than 1,000 kilometers of border walls erected around the European Union states since 1990. India has built a fence along most of its 2,500-mile border with Bangladesh, whose people are among the most vulnerable in the world to sea-level rise.

The United States, of course, has its own wall-building agenda — literal ones, and the figurative ones that can have a greater effect. On a walk last August from one of El Paso’s migrant shelters, an inconspicuous brick home called Casa Vides, the Rev. Peter Hinde told me that El Paso’s security-oriented economy had created a cultural barrier that didn’t exist when he moved here 25 years earlier. Hinde, who is 97, helps run the Carmelite order in Juárez but was traveling to volunteer at Casa Vides on a near-daily basis. A former Army Air Forces captain and fighter pilot who grew up in Chicago, Hinde said the United States is turning its own fears into reality when it comes to immigration, something he witnesses in a growing distrust of everyone who crosses the border.

That fear creates other walls. The United States refused to join 164 other countries in signing a global migration treaty in 2018, the first such agreement to recognize climate as a cause of future displacement. At the same time, the U.S. is cutting off foreign aid — money for everything from water infrastructure to greenhouse agriculture — that has been proved to help starving families like Jorge A.’s in Guatemala produce food, and ultimately stay in their homes. Even those migrants who legally make their way into El Paso have been turned back, relegated to cramped and dangerous shelters in Juárez to wait for the hearings they are owed under law.

There is no more natural and fundamental adaptation to a changing climate than to migrate. It is the obvious progression the earliest Homo sapiens pursued out of Africa, and the same one the Mayans tried 1,200 years ago. As Lorenzo Guadagno at the U.N.’s International Organization for Migration told me recently, “Mobility is resilience.” Every policy choice that allows people the flexibility to decide for themselves where they live helps make them safer.

Are you a teacher looking for a way to use this project in your classroom? You can find resources from the Pulitzer Center here .

But it isn’t always so simple, and relocating across borders doesn’t have to be inevitable. I thought about Jorge A. from Guatemala. He made it to the United States last spring, climbing the steel border barrier and dropping his 7-year-old son 20 feet down the other side into the California desert. (We are abbreviating his last name in this article because of his undocumented status.) Now they live in Houston, where until the pandemic, Jorge found steady work in construction, earning enough to pay his debts and send some money home. But the separation from his wife and family has proved intolerable; home or away, he can’t win, and as of early July, he was wondering if he should go back to Guatemala.

And therein lies the basis for what may be the worst-case scenario: one in which America and the rest of the developed world refuse to welcome migrants but also fail to help them at home. As our model demonstrated, closing borders while stinting on development creates a somewhat counterintuitive population surge even as temperatures rise, trapping more and more people in places that are increasingly unsuited to human life.

In that scenario, the global trend toward building walls could have a profound and lethal effect. Researchers suggest that the annual death toll, globally, from heat alone will eventually rise by 1.5 million. But in this scenario, untold more will also die from starvation, or in the conflicts that arise over tensions that food and water insecurity will bring.

If this happens, the United States and Europe risk walling themselves in, as much as walling others out. And so the question then is: What are policymakers and planners prepared to do about that? America’s demographic decline suggests that more immigrants would play a productive role here, but the nation would have to be willing to invest in preparing for that influx of people so that the population growth alone doesn’t overwhelm the places they move to, deepening divisions and exacerbating inequalities. At the same time, the United States and other wealthy countries can help vulnerable people where they live, by funding development that modernizes agriculture and water infrastructure. A U.N. World Food Program effort to help farmers build irrigated greenhouses in El Salvador, for instance, has drastically reduced crop losses and improved farmers’ incomes. It can’t reverse climate change, but it can buy time.

Thus far, the United States has done very little at all. Even as the scientific consensus around climate change and climate migration builds, in some circles the topic has become taboo. This spring, after Proceedings of the National Academy of Sciences published the explosive study estimating that, barring migration, one-third of the planet’s population may eventually live outside the traditional ecological niche for civilization, Marten Scheffer, one of the study’s authors, told me that he was asked to tone down some of his conclusions through the peer-review process and that he felt pushed to “understate” the implications in order to get the research published. The result: Migration is only superficially explored in the paper. (A spokeswoman for the journal declined to comment because the review process is confidential.)

“There’s flat-out resistance,” Scheffer told me, acknowledging what he now sees as inevitable, that migration is going to be a part of the global climate crisis. “We have to face it.”

Our modeling and the consensus of academics point to the same bottom line: If societies respond aggressively to climate change and migration and increase their resilience to it, food production will be shored up, poverty reduced and international migration slowed — factors that could help the world remain more stable and more peaceful. If leaders take fewer actions against climate change, or more punitive ones against migrants, food insecurity will deepen, as will poverty. Populations will surge, and cross-border movement will be restricted, leading to greater suffering. Whatever actions governments take next — and when they do it — makes a difference.

The window for action is closing. The world can now expect that with every degree of temperature increase, roughly a billion people will be pushed outside the zone in which humans have lived for thousands of years. For a long time, the climate alarm has been sounded in terms of its economic toll, but now it can increasingly be counted in people harmed. The worst danger, Hinde warned on our walk, is believing that something so frail and ephemeral as a wall can ever be an effective shield against the tide of history. “If we don’t develop a different attitude,” he said, “we’re going to be like people in the lifeboat, beating on those that are trying to climb in.”

Abrahm Lustgarten is a senior environmental reporter at ProPublica. His 2015 series examining the causes of water scarcity in the American West, “Killing the Colorado,” was a finalist for the 2016 Pulitzer Prize for national reporting. Meridith Kohut is an award-winning photojournalist based in Caracas, Venezuela, who has documented global health and humanitarian crises in Latin America for The New York Times for more than a decade. Her recent assignments include photographing migration and childbirth in Venezuela, antigovernment protests in Haiti and the killing of women in Guatemala.

Reporting and translation were contributed by Pedro Pablo Solares in Guatemala and El Salvador, and Louisa Reynolds and Juan de Dios García Davish in Mexico.

Data for opening globe graphic from “Future of the Human Climate Niche,” by Chi Xu, Timothy A. Kohler, Timothy M. Lenton, Jens-Christian Svenning and Marten Scheffer, from Proceedings of the National Academy of Sciences. Graphic by Bryan Christie Design/Joe Lertola.

Maps in Central America graphics sequence show total population shift under the SSP5 / RCP 8.5 and SSP3 / RCP 8.5 scenarios used by the U.N.’s Intergovernmental Panel on Climate Change, and it is calculated on a 15-kilometer grid. A cube-root scale was used to compress the largest peaks.

Projections based on research by The New York Times Magazine and ProPublica, with support from the Pulitzer Center. Model graphics and additional data analysis by Matthew Conlen.

Additional design and development by Jacky Myint and Shannon Lin.

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Climate Migration: An Impending Global Challenge

For months, we have watched the crisis at the Mexican border as migrants tried to enter the U.S. In March, the U.S. Customs and Border Protection office estimated that there were 171,700 people attempting to cross the border—the highest number in 20 years. About 30 percent were families, of which one third were refused entry under Title 42, a public health statute.

The number of unaccompanied children arriving and being held in custody in U.S. border shelters hit over 5,700 in March. And this week, five unaccompanied girls between the ages of seven and 11 months were found at the Texas-Mexico border. While a migrant surge occurs every year as people come to the U.S. for seasonal work, the record number of children being sent by themselves is likely a sign of desperate conditions back home.

Most of those coming to the U.S. are residents of Guatemala, Honduras, and El Salvador, which are considered some of the most dangerous places on Earth. These countries are poor and plagued by gang violence, extortion, and government corruption.

Last year, they were hard hit by COVID, and then two back-to-back hurricanes in November, which killed more than 200 people. The storms displaced over half a million people, buried houses under mud, and destroyed 40 percent of the corn crop and 65 percent of the beans. Many people lost homes, access to clean water, and their livelihoods. The governments did not offer much help.

Climate change — as embodied by the hurricanes — may have been the precipitating factor that pushed many to try to cross the Mexican border into the U.S., but it is usually one of many reasons that people decide to move.

Alex de Sherbinin, associate director for Science Applications and a senior research scientist at the Earth Institute’s Center for International Earth Science Information Network, said, “Climate change, if it’s not currently the main driver of migration, tends to operate indirectly, and will continue to do that. But as the number of severe and extreme weather events or climate-related disasters increases, we’re going to see more migration and more of that may be directly triggered by it.”

Most ongoing migration occurs in response to fast-onset events, such as extreme weather, and usually results in short-term displacement within the person’s own country. This is naturally easier than migrating to another country, and occurs more than three times as often as international migration. But recurring temporary displacements can often lead to permanent displacement. As climate change impacts intensify and living conditions in certain areas gradually worsen, affecting land productivity, access to clean water, food security, and livelihoods, more and more people will likely be forced to leave their homes and potentially cross borders into other countries.

Climate change and migration

For thousands of years, humans have lived mostly on lands where a limited range of comfortable temperatures enabled an abundance of food to grow. Today, only one percent of the world is barely tolerable due to heat; but by 2070, extremely hot zones could make up almost 20 percent of the land, which means that a third of humanity could potentially be living in uninhabitable conditions. For every degree of temperature increase, it’s estimated that one billion people are pushed out of the hospitable zone.

The impacts of climate change — sea level rise, heat waves, storms, drought, and wildfires — will influence global migration. The New York Times reported that 40.5 million people across the planet were displaced in 2020—the most in 10 years—largely due to these impacts. The 2018 World Bank report Groundswell , which the Earth Institute’s de Sherbinin and Susana Adamo worked on, cited estimates that 30 to 143 million climate migrants may be forced from their homes by climate change impacts by 2050. The Groundswell II report, due out in July and covering all developing countries, pushes the upper bound to more than 200 million.

By 2035, the frequency of major hurricanes is expected increase by 12 percent in the South Indian Ocean, 14 percent in the Atlantic, and 41 percent in the South Pacific compared to 1986-2005 averages. Between now and 2100, sea levels could rise between two and 6.9 feet, submerging millions of homes around the world; sea level rise also creates larger storm surges and can cause saltwater contamination of farmland and drinking water supplies.

Drought has displaced 800,000 within their own countries each year since 2017; in the future, dry regions are expected to get drier still. And over the last decade, wildfires around the world have forced more than 200,000 people per year to leave home; 75 percent of them were in the U.S. Moreover, scientists also believe that there will be more compound weather events , such as flash floods and mud slides that occur after wildfires.

In 2017, approximately 23 million people around the world were displaced due to sudden extreme weather events. Another 44 million or so were displaced due to “humanitarian crises,” likely exacerbated by the cascading effects of climate change. For example, climate experts believe the extreme drought in Syria led to its civil war in 2011. And as crops fail and livelihoods are lost, terrorist groups recruit more desperate people and violence spreads. In countries without the resources to deal with climate change impacts and care for their people, conflicts over resources arise. A recent report by the National Intelligence Council predicted that climate change effects will increase migration, which in turn will put a strain on both origin and destination countries and potentially trigger disputes that could become national security concerns.

Climate migrants of the future

The Groundswell report focused on migration in sub-Saharan Africa, South Asia, and Latin America, which together comprise 55 percent of the developing world’s population. It projected that, if we do not take bold climate action to reduce greenhouse gas emissions and help developing countries, 143 million people from these regions could be forced to move within their own countries to flee the effects of climate change. Migration could also accelerate after 2050 due to stronger climate impacts and population growth. If we can act to stem climate change, the number could be reduced to between 31 and 72 million. Extreme heat events, declining water availability, diminishing snowpack that feeds river basins, and sea level rise will drive people from “hot spots”— such as low-lying cities, coastlines, and places with water scarcity and decreasing crop yields. These migrants will gravitate toward places with a more hospitable climate for agriculture and more job opportunities.

Another study found that higher tides due to sea level rise could affect the land that 150 million people live on by 2050. If the melting of the Antarctic ice sheets picks up speed, 300 million could be affected and up to 480 million by 2100. Seventy percent of the people who would be affected live in eight Asian countries: China, Bangladesh, India, Vietnam, Indonesia, Thailand, the Philippines, and Japan.

Sea level rise has already overtaken eight Pacific islands, forcing the residents to migrate, and two more islands will soon disappear. By 2100, it’s estimated that 48 islands will have been submerged.

Parts of the U.S. are increasingly difficult to live in because of drought, floods, hurricanes, wildfires and sea level rise. A collaborative effort between ProPublica and the New York Times predicted that 162 million Americans will experience a decline in the quality of their environment and by 2070, four million could be living outside of their comfort zone. Because California has experienced record-breaking heat waves and rampant wildfires, with the wildfire season getting longer each year, many Californians are already moving to Idaho, Texas, Oregon and Washington.

Another researcher projected that rising sea levels will force 13 million Americans to move away from the coasts, and that in-land cities such as Atlanta, Orlando, Houston and Austin could each get 250,000 new residents by 2100.

Flooding and high tide are jeopardizing the Quileute Tribe’s school in northwest Washington, forcing the tribe to move the school and tribal government seat 2.5 miles away. In Louisiana, residents of low-lying Isle de Jean Charles are being moved 40 miles to higher ground in the first federally funded U.S. community resettlement project resulting from climate change.

Migration can be considered an adaptation to climate change, as those facing increasingly dire living situations who have the means will likely move. Most people don’t want to leave home, but if they feel they have no choice, they will usually first move from the countryside to a nearby city. If these cities lack the infrastructure or resources to support new residents, they could become overwhelmed.

And migrants with few resources and opportunities often end up living in slums, which are more susceptible to the impacts of climate change and chaos. Today half the global population is urban; the World Bank has estimated that by 2050, 67 percent of humanity will live in cities, with 40 percent of them living in slums by 2030.

Governments in many countries are already reacting to the waves of migrants by holding them in detention centers and erecting walls—Hungary closed off its border with Serbia, India constructed a fence on its Bangladesh border, and under Trump, the U.S. built its own wall. The anti-immigration sentiment has also ushered into office more nationalist governments around the world.

Meanwhile, as the wealthy are able to move to higher or cooler ground or to a more resilient location, some of the most vulnerable people without the means to move—like the poor or elderly—become trapped. This becomes a vicious cycle: As people abandon the community, there is less of a tax base to pay for social services, and those who are left behind and need public support suffer more as they become increasingly desperate. The disparity between rich and poor and their ability or inability to deal with climate change will almost certainly end up creating even more social division than exists now.

Climate migrants have no legal protection

Right now, the world is unprepared to meet the challenge of climate migration. No country offers asylum or legal protection to climate migrants. Because climate change cannot always be identified as the sole or principal reason for migrating, climate migrants have little recourse within current international or U.S. laws. They are not considered “refugees” because they do not fit under the 1951 U.N. Refugee Convention, the U.N.’s legal document that protects refugees—defined as displaced people “who have a well-founded fear of being persecuted because of their race, religion, nationality, membership of a particular social group or political opinion , and are unable or unwilling to seek protection from their home countries.”

While some experts believe climate migrants should be included under the “refugee” rubric, others argue that doing so would water down a convention that is already ignored by many countries. De Sherbinin said, “The fact is that Western governments have shown very little desire or inclination to receive migrants from other parts of the world—refugees—even by current standards, so to broaden the definition, you run the risk that people or governments will just say, ‘I’m opting out,’ or ‘I’m not even going to be part of this convention.’ It may be more appropriate to have this be a matter of national decision-making, so governments can decide whether they want to expand the definitions under which they receive refugees.”

The U.N. High Commissioner for Refugees does provide relief help and planned relocation guidance to the “disaster displaced,” and in 2019, appointed a special advisor to help shape the agency’s climate change agenda.

The Global Compact for Safe, Orderly and Regular Migration , an agreement adopted in 2018 by 164 countries, but not the U.S., helps countries prevent displacement due to climate change and provide support to those who are forced to migrate. It is the first international agreement to clarify how countries should deal with international migration, but it is not legally binding.

Because there is no organization that oversees migration, displaced people go wherever they can and not necessarily where it would be best for them to go. As climate migration increases, the situation will likely become more chaotic and overwhelming unless legal and social frameworks are created for the displaced. However, given the current nationalistic and anti-immigrant atmosphere, trying to create an international legal framework to protect climate migrants might actually lead to reducing refugee protections, not extending them.

There are no easy solutions

While there are no easy answers to the complex challenge of climate migration, here are some ideas that have been proposed to make it less chaotic and more humanitarian.

-Enable free movement between member states. For example, the Caribbean has Free Movement Agreements for climate migration. During the 2017 hurricane season, the governments allowed displaced people to move to other islands, waived the need for travel documents and work permits, granted indefinite stays to the displaced, and helped with resettlement.

-Create a Western Hemisphere regional compact on permanent displacement to expand protection and status for those who have been permanently displaced over an international border by climate change impacts.

-Plan relocation of villages and communities from areas where climate change impacts are threatening. In the Pacific Islands, Vanuatu has developed safeguards and operating procedures for relocation which include technical expertise and financial assistance.

-Ensure that cities are better able to deal with an influx of migrants through investments in infrastructure, sanitation and health services, education, and opportunities for skills and job training.

-Fund more research on how climate change will shape migration so that governments can better predict migration and prepare for it.

-Set up a system of criteria and proof to determine if someone has a credible claim that they were harmed by climate impacts, since this is necessary for the application of laws and rules.

-Build climate migration into policies and long-term planning. This would include helping communities stay where they are by investing in resilience, job opportunities, education and social safety nets. For climate migrants, create incentives to move to low-risk, high-opportunity places. For example, Bangladesh is creating “climate-resilient, migrant-friendly” towns to encourage migrants to move to secondary cities rather than to already overcrowded major cities.

-Pay climate reparations. “The historically largest emitters owe something to the countries that are now being impacted most heavily by climate impacts,” said de Sherbinin. “And providing them with assistance is no longer just a matter of giving handouts—it’s actually an obligation. Because we [wealthy countries] set up the whole climate problem [through our emissions] for many of these countries that have contributed so little to it.”

What President Biden is doing

In an attempt to address the factors that make people want to enter the U.S., President Biden has proposed $4 billion in aid to help Honduras, El Salvador and Guatemala deal with poverty, lack of jobs, government corruption, violence and climate change. He has also announced $310 million of emergency funding to help displaced people. These measures, however, could paradoxically increase migration by giving more people the means to move.

Biden has also issued an executive order for the creation of a report on climate change and migration, with recommendations for the resettlement and protection of migrants. The mayors of 15 cities, including New York, Los Angeles, Chicago, Houston and others, have asked to be consulted for the report, as they “deal with the impacts of climate change and migration on a daily basis.” De Sherbinin is also part of an expert group organized by Refugees International to advise the Biden administration on shaping policies for climate migration.

Under Trump, the number of refugees allowed into the U.S. was set at an historic low of 15,000. President Biden has now raised the refugee cap to 62,500, and plans to increase it to 125,000 in 2022. A number of Republicans criticized the decision as irresponsible and dangerous.

“People in the U.S. perceive that migrants are a burden,” said de Sherbinin. “The reality is the data just don’t prove that in any way. Look at migrants who pay taxes—I’m talking about the undocumented—who are working hard contributing to society. They’re not on welfare, they don’t even qualify for welfare. They’re the ultimate ‘sink or swim’ people who are going to have to pull their own weight. Definitely, there’s a need to recognize and dispel some of the myths about migrants being parasites. But I think, frankly, most of the fear and concern is borne out of a racist reaction to people who are Brown and Black and other colors, and don’t speak our language. They are perceived as a threat.”

The U.S. could actually stand to benefit from an influx of immigrants because it, like other industrialized countries, is facing a demographic decline, which could lead to slow growth and a weakening economy. Migrants who come to the U.S. for better job opportunities would stimulate economic growth through their labor, their buying power and the taxes they pay.

ProPublica and the New York Times modeled international climate migration, as well as political responses to climate change and migration. It showed that how leaders respond to climate change and migration will make a huge difference in how much human suffering there will ultimately be. If they fight climate change aggressively, manage migration humanely, and invest in resiliency, there will be less poverty, less migration, and enough to eat, and these outcomes could help the world be a more stable and peaceful place.

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Global Migration in the 21st Century: Navigating the Impact of Climate Change, Conflict, and Demographic Shifts

Story highlights.

World Development Report 2023: Migrants, Refugees, and Societies synthesizes over two decades of research on migration, offering insights from the World Bank and other experts.
It introduces the Match and Motive Matrix, a tool combining labor economics and international law to enhance migration policy effectiveness, identifying four distinct types of cross-border movement.
The report emphasizes the urgent need for new research on migration, highlighting the significant role of global factors like climate change, conflict, and demographic changes in shaping future migration trends.

Globally, approximately 184 million people, or 2.3% of the world population, live outside their country of citizenship. This highlights the growing complexity of human mobility, which will increasingly be driven by factors like climate change, conflict, divergent demographic trends, and income inequality. These forces are not only pushing more people to relocate for better opportunities but also presenting growing challenges and opportunities for migration policy across various levels of development in the decades to come.

The debate over migration policy is often polarized and contentious. While empirical studies show positive impacts of migration on labor markets , business performance , and health outcomes in host countries, public opinion often views immigration with apprehension and fear.

While destination countries grapple with the trade-offs of hosting migrants, origin countries face challenges such as brain drain and education system costs. With migration expected to increase, effective policy-making is crucial in both origin and destination countries.

World Development Report 2023 and the Match and Motive Matrix

In a recent Policy Research Talk, World Bank economists Quy-Toan Do and Çağlar Özden delved into the subject of migration, highlighting key findings from World Development Report 2023: Migrants, Refugees, and Societies . Both migrants themselves and seasoned researchers in the topic, Do and Özden co-directed the report (along with Xavier Devictor ), which starts with the recognition that cross-border movements inherently involve complex policy trade-offs. At the same time, it distinguishes between the different factors motivating migration in order to better tailor policy responses to distinct types of movement.

To shed light on the decision-making process and policy trade-offs, Do and Özden presented the primary framework featured in the report—the innovative Match and Motive Matrix (Figure 1). The Matrix gives policy makers a powerful tool by integrating many key issues related to migration into a single graph. The Matrix focuses on two factors: the alignment of migrants' skills and attributes with the needs of destination countries, and the motives driving their movements. “Fundamentally, this framework allows us to understand that all migration does not have to be seen as the same phenomenon,” explained Do. “The migrants’ objectives are different, which means the policy trade-offs are different, so the resulting policies need to be different.”

Figure 1: The Match and Motive Matrix

The Matrix combines two perspectives on migration. The match considers whether the migrant's contribution to the destination country outweighs the costs they impose. A strong match occurs, for example, when the labor market benefits of the migrant exceed the costs of integration, while a weak match arises when the costs outweigh the benefits. Meanwhile, the motive dimension of the matrix takes into account whether the destination country has an obligation to host the migrant under international law obligations. Individuals who relocate due to a well-founded fear of harm or persecution in their home country fall under the definition of refugees and are entitled to international protection.

For migrants with a strong match to begin with, the report recommends that destination countries focus on maximizing gains through policies like providing migrants access to labor markets, recognizing their skills and qualifications, and protecting their rights. When the match is weaker the focus then shifts towards reducing the need for migration in the case of distressed migrants, and towards ensuring sustainability and sharing costs across the international community in the case of refugees. By highlighting the diversity of migration motivations as well as the range of appropriate policy approaches, this matrix serves as a valuable guide for policy makers navigating a complicated set of decisions. The overarching aim is to underscore that migration should ideally be driven by choice rather than desperation or necessity, with benefits for destination countries outweighing the associated costs.

Growing Global Pressures Demand a Renewed Migration Research Agenda

While World Development Report 2023 compiles new research and introduces an innovative framework, it also brings attention to the existing gaps in our knowledge. A large body of research documents traditional factors driving migration like the vast disparities in wages between countries, but significant uncertainties remain. Three global forces in particular will shape migration in the 21 st century in ways that are still only partially understood.

The first uncertainty stems from rapid demographic shifts occurring worldwide. “We are at an inflection point because of demography,” said Özden. “It is the first time in human history that we are witnessing a peaceful population decline in a large number of countries.” High-income countries are aging as people live longer and fertility rates decrease. Simultaneously, middle-income countries like Mexico and India are rapidly transitioning to lower fertility rates, becoming rich before becoming old. Lower-income countries are now leading in terms of fertility; their young populations will be in high demand if they have the human capital demanded in the global labor markets, but will be struggling otherwise. Middle-income countries, whose fertility rates are falling rapidly, may shift from being predominantly origin countries to destination countries (Figure 2). As a result of declining working-age populations in high- and middle-income countries, in the next few decades migration may increasingly be driven by the needs of destination countries, which will have to compete for a shrinking pool of qualified workers.

Figure 2: The Number of Children Born per Woman in Middle-income Countries

Figure 2: Number of Children Born per Woman

Second, challenges brought about by climate change are becoming increasingly influential in reshaping patterns of human movement. To date, there is evidence that climate-related cross-border migration has occurred on a small scale. However, a much larger question remains: what will happen when climate change begins to push entire groups of people across national borders? With approximately 40 percent of the global population living in places of high vulnerability to climate change, this remains a pressing issue which demands deeper exploration. Whether and how much climate change will amplify international movements in the coming decades depends on global collaboration to adopt and implement policies for mitigation and adaptation now.

Third, conflict and violence will undoubtedly continue to cause mass movements of refugees, as recent conflicts in Ukraine and the Middle East attest.

Compounding all of these uncertainties is the fact that these drivers of mobility are often closely correlated. The very same countries are often facing the combined challenges of demographic transition, climate vulnerability, poverty, and high fragility (Figure 3). At the same time, Özden emphasizes that “these compound drivers of mobility are big development challenges, and you cannot address one at a time. The difficult types of mobility we see are symptoms of underlying development challenges.”

The interconnected web of development challenges underscores the complexity of addressing migration issues, emphasizing the need for comprehensive approaches that address root causes. Furthermore, mitigating the compounding drivers of migration requires a united global effort, pointing to the critical role of international cooperation in shaping the future of human mobility.

Figure 3: Four Maps Highlight the Correlation between GDP per Capita, Conflict and Fragility, Vulnerability to Climate Change, and Fertility

World Development Report 2023 Is Only the First Step in Understanding Migration in the 21 st Century

Given the growing significance of migration policy and the yet unknown impacts of shifting demographics and climate change, it’s evident that a substantial research agenda lies ahead. While World Development Report 2023 has initiated this exploration, there remains a vast landscape to be covered and substantial research to be completed. Over the past 20 years, researchers from the World Bank’s Development Research Group have been actively engaged in studying human migration. For instance, in examining successful models, Columbia stands out for its refugee regularization programs . Other research notes that deciding to migrate is not a purely economic decision; the “ fears and tears ” faced by an individual also present barriers to movement, highlighting the importance of addressing the individual perspective while implementing policies at the state level.

“Migration is necessary, not only for developing countries, but for all countries at all levels of income,” said Do. Investing in a renewed research agenda will help individual migrants, origin and destination countries, and the global community reap the greatest benefits from it.

World Development Report 2023: Migrants, Refugees and Societies

Event Information
World Development Report 2023
Summary of the World Development Report 2023 Key Findings
Quy-Toan Do (Co-Director, 2023 World Development Report, & Lead Economist)
Çağlar Özden (Co-Director, 2023 World Development Report, & Lead Economist)
Development Research Group

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Climate Change and Migration: An Overview for Policymakers and Development Practitioners

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POLICY PAPERS

This brief is based on the CGD policy paper, “Climate Change and Migration: An Omnibus Overview for Policymakers and Development Practitioners” (Sam Huckstep and Michael Clemens, 2023). Read the full paper here .

Climate change will have major ramifications for migration at every level: domestic, regional, and international. While most migration affected by climate change will be internal, the international system is unprepared and inadequate for the needs that will arise. This brief reviews issues faced in the governance of climate-affected migration at the internal, regional, and international levels and proposes policy actions in numerous spheres of action. Additional details are available in the related paper.

Key policy recommendations

1. regional free movement should be facilitated.

Most migration in the context of climate change remains regional. In several regions, free movement is already de jure established through agreed protocols, but requires implementation support. This is a high-potential governance option, allowing climate-vulnerable populations:

Access to safe territory
Rights in a foreign country
Lasting solutions elsewhere
Circular movement
Pre-emptive mobility

Crucially, regional free movement does not require migrants to justify the cause of their mobility. The regional economic communities implementing free movement may however lack implementation capacity. Where possible, this should be supported. Actors external to the region supporting border securitisation should consider whether this maintains policy coherence with development and climate adaptation objectives. Actions to support regional free movement include:

Supporting capacity-building of secretariats
Supporting increased access to travel documents
Facilitating bilateral pilot free movement regimes, to be scaled up
Undertaking bilateral border fee waivers
Reducing border corruption
Ensuring that populations are aware of their rights within free movement areas

2. A new institutional arrangement for climate-conscious labour migration is needed

Beyond the regional level, few options currently exist for adaptive international movement in the context of climate change. The refugee system does not protect those moving due to disaster. Reforms are unlikely to be possible. Any effort to introduce a protection category for ‘climate migrants’ or similar would face major conceptual and operational challenges.

There are currently three main pathways through which protective stay in third countries can be made possible:

Humanitarian pathways broadly defined, most prominently asylum under the 1951 Convention
Family reunification
Labour visas

Humanitarian pathways face political challenges and operational issues. Family reunification will very seldom offer access to adequate numbers of people in need of mobility. Educational pathways are not mentioned due to their temporary nature.

Labour pathways are the sole realistic means of providing international mobility to climate-affected persons moving beyond their region or living in regions without free movement agreements.

Labour pathways are however institutionally wholly demand-driven. We propose that states should urgently incorporate supply-side needs, assessing the need for and benefits from movement in areas of origin in a timely manner. This would allow states to prioritise certain populations for access to movement. Implementing this requires:

A labour migration research agency with a mandate and capacity to assess the external as well as internal impacts of migration
Either a whole-of-government approach to labour migration or, more likely, an Office of the Special Commissioner for Migration, learning from trade policy to govern migration coherently

Mobility could be permanent, from an uninhabitable area, or temporary, allowing remittances for reconstruction and adaptation.

3. Adaptive internal migration should be supported

For populations vulnerable to climate shocks –such as those dependent on agriculture; members of marginalised communities; or those in debt— internal migration can spread risk and allow adaptation. Internal migration may however be inaccessible due to lack of information and high costs.

Governments should evaluate assisting populations in undertaking circular internal mobility, especially during agricultural communities’ ‘famine seasons’. This can be supported through:

Subsidised rural-urban transport
Training for urban jobs in rural areas or upon arrival
Assistance with finding jobs in areas of destination
Facilitated skill recognition portability
Provision of information on jobs and wages outside the area of origin

4. Preparations for internal migration must be made

Migration can be highly effective, even transformative, for climate-affected households. It can however cause negative externalities. These include the spread of infectious diseases, which may accelerate as climates continue to warm; strain on urban services; and exploitation of migrants themselves.

Governments should be aware of the inter-relationships between migration and numerous other policy areas. Migration should be mainstreamed into other policy areas, and climate change should be mainstreamed into all policy areas. Preparations should include:

Climate-conscious zoning of urban construction options, to avoid incentivising the construction of properties in areas vulnerable to future weather shocks
Preparations of assistance in planned relocation, including establishing transparent criteria for movement and funding regimes for relocation
Increased awareness of internal labour market needs, to support internal adaptive migration
Support for urban areas in receiving migrants, including in service provision
Reform of social protection arrangements where necessary, especially increasing the portability of social protection access
Evaluating the risk of exploitation of migrant workers, and preparing processes for their protection
Preparing healthcare systems for potential increases in transmission of diseases, by mapping the epidemiological profiles of areas of origin vs. areas of destination and preparing to provide health interventions where necessary
Preparing targeted support towards those ‘left behind’ in areas of origin, who may (potentially for a short time) be more vulnerable

5. A better understanding of the impacts of climate change on displaced populations is needed

Most attention in the climate-migration nexus has been given to those perceived, or expected, to move as a result of climate change . Less research has been conducted on the impacts of climate change upon those already displaced due to conflict or other shocks.

Displaced populations are not necessarily more vulnerable than other vulnerable populations, but in many contexts they will be. Those living in camps may have less access to energy, healthcare, and food; they also, depending on their context, may have fewer rights, including the right to work or to move.

Camps may be located in areas that themselves face climate shocks, often through flooding. More research in this area is required. In the meantime, governments and other actors should:

Ensure that where possible refugees and IDPs are not located in areas exposed to climate hazards
Provide displaced populations with rights, including to work and to move
Ensure that displaced populations have access to healthcare and adequate provision of water, sanitation and hygiene needs, which can become more challenging in flood-affected contexts
Where possible limit the impact of displaced populations upon the local environment, such as by providing alternative energy sources to biofuels

6. Diaspora engagement for climate adaptation should be stepped up

Remittance flows far outstrip ODA and FDI provision. Where possible, governments should seek to engage with diasporas and migrants abroad to channel remittances towards adaptation projects. This should not be taken for granted: remittances are private capital, the result of a household investment in mobility, and are used for the priorities of the migrant’s local network. Nor should migration and remittance-sending be allowed to substitute for state actions.

Where options exist for mobilising remittances in ways that are attractive to migrants, their communities of origin, and governments, they should be pursued:

The cost of sending remittances should be reduced, allowing migrants to send more in response to or in preparation for shocks
Early-warning systems should be publicised to households in hazard-exposed areas, allowing them to request funds from migrant connections in advance of shocks for better results
Circular migration programmes should incorporate efforts to increase ‘non-financial remittances’, training migrants for climate adaptation in their area of origin
Diaspora networks should be tapped for their expertise
Individuals deciding remittance uses in areas of origin should be engaged with to inform their choices, including via local community leaders, to avoid maladaptive investments
Migrants retuning can be provided with business support to create growth and diversification
Green diaspora bonds could be trialled, allowing diasporas to invest their savings in adaptation efforts (dependent on conditions in the country of origin)
Remittance matching programmes can provide a discount for state adaptation financing
Crowdfunding initiatives can be used to pool funding and support enterprises or initiatives in countries of origin, potentially with returns for funders
Remittances can be pooled at the community level or above to fund local public goods

Key takeaways

The climate-migration nexus is complex. Climate change is having, and will have, multi-faceted impacts on a very wide range of issues. These will affect migration through direct and indirect pathways. Migration is multicausal, and while climate change will affect mobility choices, so too will many other factors. Attributing causality in cases of movement is therefore almost always hard.

The issue’s complexity is not a justification for inaction . Preparations for the effects of climate change on migration must be made, and they must be holistic, without neglecting any of the many different affected policy areas.

Migration is mostly internal. Those moving in the context of climate change are most likely to remain within their country, moving in rural-urban circular patterns to make up climate-induced income shortfalls. This is not a universal rule: citizens of Small Island Developing States, for example, may ultimately need to leave their countries. In other contexts, similarly, the trend may not be permanent.

Where migration crosses borders, it generally remains regional . Persistent climate shocks reduce the assets of those exposed to them; this makes it harder to access long-distance migration. The spectre of a ‘tidal wave’ of international ‘climate refugees’ is to be treated with high scepticism.

At the international level, few options exist for those moving in the context of climate change . The refugee system offers scant protection to those not fleeing persecution, and there is little prospect of reform. While some humanitarian pathways are being created for those affected by sudden-onset disasters, people affected by slow-onset disasters are more numerous and have little recourse. New approaches are necessary. Labour migration options are the most likely to succeed, and should be adapted for emerging needs.

Predicting climate-affected migration is highly challenging . Both climate modelling and migration modelling present problems. Conceptual challenges regarding causality; poor historical data; our inability to predict border governance choices; the inherent unpredictability of shocks; and uncertainty regarding future adaptation choices all hinder our ability to make accurate forecasts of movement.

If factors other than climate change militate against migration, international movement could go down. Other factors, such as border governance choices and economic trends, have a far bigger role in determining migration outcomes than climate events.

People most affected by climate hazards will often become involuntarily immobile . Those whose assets are depleted by sudden- or slow-onset disasters will have lower mobility capacity. In many areas climate change will therefore cause migration to decrease. Over the longer term, however, this may not be a trend that holds, and internal ‘distress migration’ of destitute populations away from areas of shattered livelihoods must be anticipated. Indeed, ‘distress migration’ is already happening in some areas, notably the Horn of Africa.

People highly exposed to climate hazards will increasingly need relocation support . Without support, they may face unacceptably degraded living conditions in areas of origin; injury and death; or movement without dignity into further vulnerability. Few governments are yet prepared for this, and private sector actors, such as insurance providers, are currently of greater importance in deciding who can move where. Action should be taken sooner rather than later to reduce vulnerability and limit future costs. This should be culturally and socially sensitive.

Migration can allow adaptation against climate shocks. Migration can offer an insurance option to those whose livelihoods are harmed by climate shocks and increased variability, allowing them to access wages in economies not correlated with their area of origin. Money remitted back to the community of origin can be used for adaptation, such as income diversification; the payment of healthcare costs; the purchase of food; and the reconstruction or reinforcement of dwellings.

Migration can also be maladaptive . Poverty exacerbated by climate change may also, for example, make affected populations more vulnerable to exploitation when moving. If this occurs, migration meant to aid adaptation could worsen the situation. Climate-affected populations are especially exposed to debt traps, trafficking, and human slavery. Support should be provided to vulnerable populations before vicious cycles become entrenched; credit providers and intermediaries should be carefully regulated; and abusive situations should be rectified.

Members of migrant-sending households may require support in areas of origin . Those who do not migrate may remain in situ out of preference. They can however often be vulnerable in the absence of household members, and local policy should be attuned to potentially heightened challenges, especially during the period before remittances start to arrive.

Remittances are the crucial mechanism by which migration assists vulnerable populations . Movement allows higher earnings, and money can be sent back to communities of origin. This money can be used to support households during and after shocks; to facilitate movement away from hazards; and to diversify incomes away from climate-vulnerable activities. Remittances are however often not used for climate-adaptive purposes.

Opportunities to earn remittances should be facilitated . At the internal level, this could mean that subsidised transport; vocational training; and information should be provided to vulnerable populations in climate-affected areas. At the regional level, free movement should be supported where possible. At the international level, climate-vulnerable populations should where possible be prioritised for mobility pathways.

The ease of sending remittances should be increased . Remittance-sending costs are currently too high. This reduces access to adaptation funding. Where fees can be reduced, they should be.

More can be done to channel international remittances towards climate adaptation, development, and disaster risk reduction . This should not be taken for granted: remittances are household assets, and most remittances will already be earmarked for vital household uses. Remittance pooling; crowdfunding; green diaspora bonds; and climate-anticipatory remittance mechanisms may however all present options. Success requires project transparency; accountability on the part of governments and other actors involved; and trust on the part of diasporas. Remittances may supplement state or international adaptation spending, but they are not adequate in themselves, and should not be viewed as a way to reduce state obligations.

International labour pathways should be targeted towards climate-vulnerable populations where possible . Earnings from international mobility, even in low-skilled jobs, can be transformational for adaptation. This requires attention to comparative vulnerability and facilitated access for vulnerable populations. It is also likely to require new institutional arrangements.

Cities require preparation for climate-accelerated urbanisation . Rural-urban migration to support climate-affected rural livelihoods may put strain on urban services. Migrants may find themselves moving into urban sites of increased hazard, such as flood-prone informal settlements. Migrants may also become more vulnerable to shocks in urban areas, due to difficulties finding work; lack of knowledge of their new context; and disconnection from support networks and their identity. Local governments need to partner with vulnerable communities; the private sector; national government bodies; and international actors to prepare for climate-related migration into cities and intra-city movements due to climate events.

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Research for Development Outputs

Rapid evidence assessment on the impacts of climate change on migration patterns

This publication provides an assessment of the extent and quality of existing evidence on the relationship between climate change and migration

This rapid evidence assessment (REA) synthesises findings from 273 quantitative and qualitative studies published between 2005 and 2021 on the relationship between climate change and migration, with particular attention to small island states, the Bay of Bengal, East Africa, and the Sahel.

The overarching question guiding this analysis is: What are the current and likely future impacts of climate change on migration and displacement?

The authors consider:

how climate change is affecting and likely to affect patterns of migration;

how different countries and regions are affected and likely to be affected;

confidence in existing estimates and projections of climate change-related migration.

The REA finds that:

Climate-related shocks can contribute to increases and decreases in migration, and there is no upward trend in weather shock-related migration.

There is little evidence of existing impacts of long-term climatic and related changes on migration.

The is strong evidence that adaptations to climate-related shocks and hazards can reduce migration pressures, but that ‘maladaptation’ contributes to displacement and migration.

There is strong evidence that perceptions and narratives of climate change, weather shocks and local environments affect migration practices and decisions.

Poverty-affected individuals and households are particularly affected by both migration pressures and barriers to movement, and young people are the most likely to move in response to climatic pressures.

There are no rigorous global estimates of the number of people displaced by or migrating in response to weather shocks or climate change, and high-end projections of future climate-related migration are not considered credible

Selby J, Daoust G (2021) Rapid evidence assessment on the impacts of climate change on migration patterns. London: Foreign, Commonwealth and Development Office.

Rapid evidence assessment of climate change impacts on migration

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Climate Change and Migration

A story that begins with case studies of small communities facing severe threats from climate change effects and continues with a look at large populations made vulnerable by human-induced changes to Earth's climate, leveraging data from a variety of sources such as academic journals and scientific agencies.

*References to Kosovo shall be understood to be in the context of United Nations Security Council resolution 1244 (1999).

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Migration in the Context of Climate and Environmental Changes within Central Asia and to the European Union and the Russian Federation

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Preview of pub2023-041-el-migration-in-the-context-of-climate-ca-eu-rf.pdf

This report focuses on the intersection of environmental change with movements into the European Union from Central Asia. It contributes to a growing body of literature on migration in the context of climate and environmental changes,1 including movements affected by the slow- and sudden-onset impacts of climate change. The report identifies new trends in migration affecting the European Union and Central Asia and discusses the current state of legal and policy responses to these movements. It helps countries in the European Union and Central Asia fulfil commitments made in the Global Compact for Safe, Orderly and Regular Migration (hereafter the Global Compact for Migration) related to understanding the drivers of migration in the context of climate and environmental changes. The recommendations made in the report should also help European and Central Asian governments to develop policies that will enable them to respond to these movements more effectively.

Why migration in the context of climate and environmental changes

During the past 15 years, European countries and institutions, within and beyond the European Union, have given increasing attention to migration in the context of climate and environmental changes as an issue affecting Europe as a continent. In 2009, the Parliamentary Assembly of the Council of Europe adopted Resolution 1655 entitled “Environmentally induced migration and displacement: a 21st century challenge”, which outlines the importance of the issue and makes recommendations for Member States and the broader international community (Parliamentary Assembly of the Council of Europe, 2009). In 2011, the Government of the United Kingdom released a groundbreaking report on migration in the context of climate and environmental changes, often referred to as the Foresight Project, which concluded that environmental drivers interacted with economic, political, social and demographic factors to stimulate additional movements of people. In 2013, the European Commission issued a commission staff working document on climate change, environmental degradation and migration (European Commission, 2013). It called for greater knowledge, dialogue and cooperation in addressing the intersection of environmental and migration issues. More recently, the European Parliament’s Policy Department for Citizens’ Rights and Constitutional Affairs issued a report examining legal and policy responses to migration in the context of climate and environmental changes and displacement. The report recommended that the European Parliament gather “evidence on the effects of climate change and environmental change more generally on migration and displacement. It should do this in cooperation with third countries and regions that are facing mobility issues in the context of climate change and environmental degradation” (Kraler et al., 2020:89). Finally, in July 2022, the European Commission released a new staff working document on addressing displacement and migration related to disasters, climate change and environmental degradation, where it outlines the priority actions it will pursue to complement ongoing efforts “to address this truly global challenge” (European Commission, 2022:1). In particular, it aims to strengthen existing humanitarian and development actions in third countries vulnerable to climate change, and to enhance available research and knowledge production activities. In doing so, the European Commission privileges external actions to be carried out in affected third countries. No measure of protection or legal pathway to the European Union is foreseen for migrants coming from those regions.

All in all, a clear message of all these documents is the need for European countries and institutions to work more closely with developing countries in regions in which migration in the context of climate and environmental changes was likely to increase in the future.

Earlier Springs Cause Problems for Birds

A climate change induced mismatch between green up and migration may prove too much for some species. But researchers say there’s still hope

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Match Made in Migration

Birds have evolved myriad migration strategies. Some have stayed closer to home, tolerating harsh winters and readying themselves for the first food of spring. Some migrated just a bit, maybe a few hundred miles or a thousand feet in elevation. Many others learned to migrate sometimes as far as the top of North America to the bottom of South America and back. The costly journeys, often thousands of miles long, allow birds to be able to overwinter in areas with good food and breed and reproduce in similarly abundant spots.

But as climate change warms our planet, causing spring to arrive weeks earlier than it has historically, birds are struggling to keep up. It’s not just the green vegetation they miss, but the pulse of protein-rich insects many bird species consume on both their breeding grounds and their migratory stop-over points.

Biologists have been studying this over the last decade or so, and most recently a team of researchers from the universities of Oklahoma State, Yale, Cornell and other institutions, looked at the migration timing of 150 species using eBird data across the Western Hemisphere. They then contrasted that information with 20 years of satellite imagery of vegetation green up.

They found that as green up changed, largely earlier and earlier though also more erratically, birds were not keeping up.

The study looked at species spanning a breadth of sizes and life history patterns and found that the short-distant migrants may fare best. Those birds who stick closer to their breeding grounds year-round are better able to track green up more closely.

“The ones we’re most concerned with are long distance migrants,” says Ellen Robertson, co-author on the recent paper “ Decoupling of bird migration from the changing phenology of spring green-up. ” “They’re the ones flying 5, 6, 7,000 kilometers from where they winter to where they breed.”

Like the veery in Brazil, long-distance migrants have no way of knowing that when the sun tells them to leave, spring in Canada is well underway.

Scientists are only now beginning to understand what this may mean. A 2023 paper by University of California Los Angeles professor and researcher Morgan Tingley and many others looked at 41 species of migratory and resident North American birds and found that changing green up in the prior 18 years resulted in fewer eggs and chicks. Projected out another 80 or so years, and the shifts are expected begin to take a dramatic toll on populations.

Birds will still breed, Tingley says, but not quite as successfully because food will be more limited. Instead of chicks hatching as insect populations boom, those chicks may catch the end of the insect pulse. Put simply, birds may still find a buffet, just with a lot less food.

bird on the forest floor staring at the camera

Can They Evolve?

The news of a seasonal mismatch resulting in even fewer birds feels dire in the face of bird populations that are already struggling. But as countries globally attempt to address warming, individuals, local governments and land managers can also make a difference. It’s entirely possible that preventing monocultures and encouraging diverse plant species could likely help, says Scott Loss, a University of Oklahoma professor and a co-author on the most recent paper.

Tingley recommends anything to support broader bird populations, protect winter ranges and breeding grounds, and conserve migratory corridors.

Meanwhile, some amount of natural selection could support those individuals that better match the changing green up, as in, the birds who migrate earlier will make more babies. But that kind of selection will only get them so far. At some point, few or no birds will have the genetic variations required to leave winter range even earlier. At that point, populations would rely on genetic mutations, which is an evolutionary process that “takes much longer than we have,” Tingley says.

Yet he and the other researchers remain hopeful.

“I’ve generally always been impressed and surprised,” he says, “by the wide variety of creative ways that birds in the natural world are adapting to the really difficult conditions that we throw at them.”

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Published: 26 November 2019

Climate migration myths

Ingrid Boas ORCID: orcid.org/0000-0001-7842-5883 1 ,
Carol Farbotko ORCID: orcid.org/0000-0001-8257-2085 2 ,
Helen Adams ORCID: orcid.org/0000-0003-1732-9833 3 ,
Harald Sterly 4 ,
Simon Bush 1 ,
Kees van der Geest 5 ,
Hanne Wiegel ORCID: orcid.org/0000-0003-1587-7721 1 ,
Hasan Ashraf 6 ,
Andrew Baldwin 7 ,
Giovanni Bettini ORCID: orcid.org/0000-0002-1191-1913 8 ,
Suzy Blondin 9 ,
Mirjam de Bruijn ORCID: orcid.org/0000-0002-0499-8758 10 ,
David Durand-Delacre ORCID: orcid.org/0000-0001-8847-6174 11 ,
Christiane Fröhlich ORCID: orcid.org/0000-0002-1802-0419 12 ,
Giovanna Gioli 13 ,
Lucia Guaita 14 ,
Elodie Hut 15 ,
Francis X. Jarawura 16 ,
Machiel Lamers 1 ,
Samuel Lietaer 17 ,
Sarah L. Nash 18 ,
Etienne Piguet ORCID: orcid.org/0000-0002-5114-8385 9 ,
Delf Rothe ORCID: orcid.org/0000-0003-0425-262X 19 ,
Patrick Sakdapolrak 4 ,
Lothar Smith 20 ,
Basundhara Tripathy Furlong 14 ,
Ethemcan Turhan 21 ,
Jeroen Warner 14 ,
Caroline Zickgraf 15 ,
Richard Black 22 &
Mike Hulme ORCID: orcid.org/0000-0002-1273-7662 11

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Misleading claims about mass migration induced by climate change continue to surface in both academia and policy. This requires a new research agenda on ‘climate mobilities’ that moves beyond simplistic assumptions and more accurately advances knowledge of the nexus between human mobility and climate change.

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Acknowledgements

This work was funded by the Netherlands Organization for Scientific Research under grant no. VENI 451‐16‐030 and the Wageningen University Department of Social Sciences Excellence Fund.

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Ingrid Boas, Simon Bush, Hanne Wiegel & Machiel Lamers

Griffith Centre for Social and Cultural Research, Griffith University, Nathan, Queensland, Australia

Carol Farbotko

Department of Geography, King’s College London, London, UK

Helen Adams

Department of Geography and Regional Research, University of Vienna, Vienna, Austria

Harald Sterly & Patrick Sakdapolrak

United Nations University Institute for Environment and Human Security, Bonn, Germany

Kees van der Geest

Department of Anthropology, Jahangirnagar University, Dhaka, Bangladesh

Hasan Ashraf

Department of Geography, Durham University, Durham, UK

Andrew Baldwin

Lancaster Environment Centre, Lancaster University, Lancaster, UK

Giovanni Bettini

Institute of Geography, Faculty of Arts and Social Sciences, University of Neuchatel, Neuchatel, Switzerland

Suzy Blondin & Etienne Piguet

African Studies Centre, Faculty of Social Sciences, Leiden University, Leiden, the Netherlands

Mirjam de Bruijn

Department of Geography, University of Cambridge, Cambridge, UK

David Durand-Delacre & Mike Hulme

German Institute of Global and Area Studies, Hamburg, Germany

Christiane Fröhlich

School of GeoSciences, University of Edinburgh, Edinburgh, UK

Giovanna Gioli

Sociology of Development and Change Group, Wageningen University, Wageningen, the Netherlands

Lucia Guaita, Basundhara Tripathy Furlong & Jeroen Warner

Hugo Observatory, Department of Geography, University of Liège, Liège, Belgium

Elodie Hut & Caroline Zickgraf

Department of Planning, University for Development Studies, Wa, Ghana

Francis X. Jarawura

Centre for Sustainable Development Studies, Institute for Environmental Management and Land Use Planning, Université Libre de Bruxelles, Brussels, Belgium

Samuel Lietaer

University of Natural Resources and Life Sciences, Institute of Forest, Environment and Natural Resource Policy, Wien, Austria

Sarah L. Nash

Institute for Peace Research and Security Policy at the University of Hamburg, Hamburg, Germany

Human Geography, Institute for Management Research, Radboud University, Nijmegen, the Netherlands

Lothar Smith

KTH, Division of History of Science, Technology and Environment, Stockholm, Sweden

Ethemcan Turhan

College of Social Sciences, University of Birmingham, Birmingham, UK

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Boas, I., Farbotko, C., Adams, H. et al. Climate migration myths. Nat. Clim. Chang. 9 , 901–903 (2019). https://doi.org/10.1038/s41558-019-0633-3

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Published : 26 November 2019

Issue Date : December 2019

DOI : https://doi.org/10.1038/s41558-019-0633-3

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5 Decisions Everyone Will Have to Make as Climate Change Intensifies

Abrahm Lustgarten is an investigative climate reporter for ProPublica and works often with the New York Times , The Atlantic , and PBS. Previously, he was a staff writer at Fortune .

Below, Abrahm shares five key insights from his new book, On the Move: The Overheating Earth and the Uprooting of America . Listen to the audio version—read by Abrahm himself—in the Next Big Idea App.

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1. We are slowly being displaced from the climate niche for human habitat.

Throughout history, people have always moved in response to their climate. But now it is different: climate change is happening faster than any previous change. The population of the planet is unfathomably larger. 200 million people inhabited the earth when the Mayan civilization collapsed. There were 4 billion people by 1980. There could be 9 to 12 billion people by the end of the century. So, I set out to investigate how many people might move, when, and to where—to tell the story of the next great human migration.

There is an optimal temperature range for human life on this planet—a climate niche —and it is shifting towards the poles. Research suggests that between one-third and one-half of humanity (two to six billion people) will face degrading climate conditions that will force them to consider migrating as a solution, and that includes about 160 million Americans. In 2020, only 1 percent of land on the planet was too hot for traditional civilization. By 2070, 19 percent of Earth’s surface could be outside of habitable parameters for human life.

There is no place in America where we won’t have to deal with climate change; it is inescapable. Large numbers of Americans are already beginning to migrate. For the past several hundred years, the climatic sweet spot in the U.S. has straddled the middle of this country, keeping the Plains fertile, and the Southeast verdant. But within the next five decades, that sweet spot is forecast to shift sharply northward, hovering over the northern Midwest and Chicago. In a more extreme warming scenario, it moves all the way to the border of Canada, and eventually, to the other side of it.

Climate models and migration data suggests that between 13 and 160 million people (up to half of all Americans) will face the kind of degrading environment that has driven historical climate-influenced migrations. At least 13 million Americans will be displaced by coastal flooding alone. This will cause a sweeping change in the shape and location of communities across America, with vast implications for politics and economy.

2. What we do next makes a huge difference.

The same data that suggests half of humanity will fall out of our climate niche also shows that enforcing aggressive policies that cut emissions now will sharply lower the number of people displaced by warming. By limiting global average temperature increases to 1.5 degrees Celsius from the 2.7 degrees we are now tracking towards, the number of global climate migrants could be reduced by half, and the number exposed to extreme heat can reduce fivefold, from 22 percent to just five percent of people on the planet.

For the U.S., there is both ample opportunity to steer what happens and to seize on the change that is going to happen if tens of millions of people move into cities and repopulate northern regions that passed their peaks decades ago. Past migrations out of the South or away from the Dust Bowl transformed American culture: our cities, music, arts, literature, sports–everything. Success in the next migration requires planning, investment, anticipation, and equity. It will demand affordable housing, infrastructure, and new schools. This can lead to new jobs, entrepreneurship, and booming growth as those things are built out.

“Success in the next migration requires planning, investment, anticipation, and equity.”

Large-scale climate driven migration within the United States is only bad news if it is ignored. Planning for it, capitalizing on it, and adjusting to it with foresight can make the United States a stronger place, full of opportunity in a warmer world.

The laws and pledges made in the U.S. so far demonstrate that while they are not painless, they are possible and have an effect: 80 percent of new energy installation is renewable and the EV battery market taking off. Evidence suggests electrifying home appliances and autos with technology already on the market could cut U.S. emissions enough to reach these global goals.

We all stand to benefit. The U.S. government estimates that holding global warming to 1.5 degrees Celsius would also sharply reduce the economic fallout of climate change, allowing our GDP to grow between one and four percent faster over the next several decades.

3. Climate migration will be an economic decision, not an environmental one.

Americans will ultimately respond to environmental change when it shows up as economic change. We are talking about a slow-moving change that will accelerate and unfold over decades, but we can see the signs now.

Americans increasingly face greater personal financial risk as climate change costs soar and insurance and other policy subsidies go away. This is changing the perception of climate change from a cultural-political issue to a household economics issue. That is the shift that will transform where people choose to live.

Farm production in the U.S. has already dropped by more than 12 percent since 1961 because of warming. Scientists estimate that by 2050, Dust Bowl–era yields will become the new norm across the Great Plains, and yields in Texas could drop by 90 percent. By 2080, crop failure will spread to more than 1,900 U.S. counties—representing more than half the country. Many places will become unfarmable, and the livelihoods they make possible will disappear.

“As household utility bills skyrocket, people will find reason to move to places with more opportunities to save.”

Coastal flooding is already ten times more common than it was in 1960. The Union of Concerned Scientists estimates that more than half a million more Americans could see their homes and streets flood at least every other week before their current 30-year mortgages are paid off. Across the country, Americans are facing suddenly unaffordable insurance premiums for flooding, wind, and wildfires–or losing that coverage entirely.

The cost of and demand for energy is also shifting. Consider this: For more than 100 years, only three U.S. cities topped 105 degrees for more than a month out of the year. By the second half of this century, 152 American cities will sustain such temperatures, requiring air conditioning in homes and factories. As household utility bills skyrocket, people will find reason to move to places with more opportunities to save.

867 counties are estimated to see economic damages of greater than $1 million each year directly due to climate change by 2040. Nationally, GDP will be reduced by 1.2 percent for every degree of future warming, costing $8.4 trillion each decade by mid-century.

4. Subsidies in the U.S. have made dangerous places seem safer than they are.

Do you ever wonder why Americans live in the places they do? We’ve known about disastrous hurricanes and sea level rise for decades, and yet the population of south Florida–the most at-risk-part–has grown ten-fold. How could it be that after five straight years of headlines about record-breaking strings of 115-degree weather (so hot that airplanes can’t take off), Phoenix, Arizona remains one of the fastest-growing cities in America?

These are dangerous places to live with potentially fiscally disastrous consequences. But Americans have moved to these places and remained blind to the risk to their savings, security, and safety because a host of subsidies and policies have hidden the true costs.

In Florida, for example, after Hurricane Andrew wiped tens of thousands of properties off the map in 1992, the free market for insurance collapsed, and companies stopped offering policies. In answer, the State of Florida created its own subsidized public plan and not only guaranteed insurance to anyone who wanted it, but promised to discount it below market rates. Now 30 states have similarly subsidized plans, from Massachusetts to California. They hold trillions of dollars in liabilities that their citizens can be assessed for as disasters mount.

The cost and availability of insurance is an indispensable signal. It is one of the most explicit ways that anyone who takes out a mortgage confronts the sustainability of their environment. Subsidizing that insurance distorts the perception of the real risks people face and shifts the fiscal responsibility onto the shoulders of taxpayers.

“Nine out of the ten fastest-growing regions in the country are most at risk from climate impacts.”

The same can be said about how the federal government has piped the Colorado River over mountain ranges and hundreds of miles to deliver water into the heart of the desert, where people pay less to use it than they do in Wisconsin. Or about the ways the U.S. Department of Agriculture pays farmers income subsidies to keep growing water-intensive crops, like cotton, in the middle of the Sonoran Desert.

Americans have gravitated toward some of the country’s most dangerous environments because government-subsidized insurance schemes and incentives steer them there. Nine out of the ten fastest-growing regions in the country are most at risk from climate impacts. As those programs begin to end, Americans face greater financial risk for remaining in dangerous places and must now recalibrate those decisions.

5. This is a highly personal dilemma.

Not a day goes by that I do not dwell on the unresolved questions of how to navigate this seismic change. But as I share in the book, I have not concluded yet that I need to move. While a part of this book is about the science, another part is about the human dilemma—the painful reckoning that goes along with deciding how and where to live in the future. That’s the universal part of this story, which every single American is going to face regardless of their politics.

We all need a guidebook of sorts for how to recognize slow-moving, imperceptible change. What does that actually look like? What does experiencing such a change feel like? Those are questions I try to answer. It’s not meant to be scary. It’s meant to help you understand the context and implications of what’s unfolding in your life, and give you signposts for the decisions you will, unfortunately, be forced to make.

Many people may never move, but there are things that you and your community will have to do so that you don’t ever have to. You may want to invest. You might want to become an activist. This will show you who needs help and what issues might benefit from your contributions. You might not think small changes matter. On the Move is meant to show you the difference in results between small change and big change. You might wish to ignore climate change in its entirety. This book will show you why you can’t, but that facing it might not mean what you think.

To listen to the audio version read by author Abrahm Lustgarten, download the Next Big Idea App today:

Listen to key insights in the next big idea app

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As climate change pushes deer north, other animals may lose out

Researchers say woodland caribou could be at risk.

As winters warm, white-tailed deer push ever northward in North America. A recent study in Global Change Biology suggests that climate change is driving these habitat shifts — changes that may further threaten woodland caribou in northern Canada.

The study used 300 remote cameras across the northern Alberta-Saskatchewan border, collecting nearly 80,000 images of white-tailed deer from 2017 to 2021 and using the images to estimate white-tailed deer density in the region over time.

Researchers chose the area because it contains a variety of landscapes altered by humans, providing an opportunity to tease out whether climate or human-caused habitat changes have a bigger influence on deer density.

Habitat alteration by humans affected the number of deer, but the effects of climate were stronger, the scientists said. When the winter was more severe, the researchers found, deer densities declined regardless of habitat alteration due to human activity. Warmer winters, in contrast, meant higher numbers of deer.

Because climate change is expected to reduce winter severity, the researchers predict that deer will push farther north as less severe winters make the habitat there more appealing.

That could have serious effects for the other animals that live in the deer’s new homes.

“Deer are ecosystem disruptors in the northern boreal forests,” Melanie Dickie, a doctoral student at the Wildlife Restoration Ecology Lab at the University of British Columbia’s Okanagan campus and a co-author of the study, explains in a news release . “Areas with more deer typically have more wolves, and these wolves are predators of caribou — a species under threat. Deer can handle high predation rates, but caribou cannot.”

Woodland caribou in northern Canada’s forests have long been threatened by habitat loss. According to Natural Resources Canada-Canadian Forest Service, these caribou tend to avoid areas with shrubs favored by deer. Parasites and diseases can also accompany deer expansion, the researchers note.

Though the region studied is relatively small given the wide distribution of white-tailed deer, the researchers conclude that even a small change in winter severity could prompt a “substantial” increase in deer in the north. The scientists call for more habitat restoration and protection to stop caribou declines, but write that climate should also be taken into account by conservationists.

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Guatemala to host ministerial summit on migration and protection

May 7, 2024

The Foreign Ministry issued a statement explaining that prior to the event at the National Palace of Culture, three parallel events involving the private sector, civil society, the academia and governments will take place.

“In this context, bilateral meetings will be held with the participating States, above all, at the headquarters of the Foreign Ministry,” the statement added.

The meeting will also be attended by officials from the United Nations High Commissioner for Refugees (UNHCR) and the International Organization for Migration (IOM), among others.

“This is a regional effort designed to promote initiatives to achieve safe, orderly, regular and humane migration and the protection of people in the context of mobility,” the Foreign Ministry stressed.

Foreign Minister Carlos Ramiro Martínez confirmed that US Secretary of State Anthony Blinken will participate in the summit and will hold a separate meeting with President Bernardo Arévalo, at which immigration, security and fighting drug trafficking will be discussed.

Mexican Foreign Secretary Alicia Bárcena said on Monday that she will meet with the Guatemalan president and Blinken to discuss the migration phenomenon at the regional level.

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COMMENTS

How does climate change affect migration?
Bower: Climate change is a threat multiplier - it can exacerbate economic insecurity or political instability, which in turn may lead to migration. In the "dry corridor" of Central America, for example, climate change extremes such as droughts may hinder crop production. Without a consistent source of food or income, a farmer may seek ...
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The migration-climate nexus is real, but more scrutiny and action are required. In 2018, the World Bank estimated that three regions (Latin America, sub-Saharan Africa, and Southeast Asia) will ...
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Understanding how climate change will shape migration in the future could help policymakers and communities prepare for these shifts. But modeling and projecting climate-related migration is a complex challenge, one that was explored by scientists from many disciplines who gathered at a National Academies workshop last month.
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Climate change and migration. For thousands of years, humans have lived mostly on lands where a limited range of comfortable temperatures enabled an abundance of food to grow. Today, only one percent of the world is barely tolerable due to heat; but by 2070, extremely hot zones could make up almost 20 percent of the land, which means that a ...
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Given the growing significance of migration policy and the yet unknown impacts of shifting demographics and climate change, it's evident that a substantial research agenda lies ahead. While World Development Report 2023 has initiated this exploration, there remains a vast landscape to be covered and substantial research to be completed.
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Climate change is likely to increase human migration, but future climate-related migration flows will depend heavily on the adaptive capacity of people living in vulnerable regions and on the ...
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There are a few things we know at this point: (1) migration is a fundamental strategy for addressing household risk arising from the environment; (2) environmental factors interact with broader ...
American climate migration
On the Move, by journalist Abrahm Lustgarten, is a poignant and meticulously researched exploration of climate change and both its imminent and long-term effects on human migration in the US.Through analysis, personal narratives, and projected future scenarios, Lustgarten unveils the stark reality of a world on the brink of massive demographic shifts driven by an increasingly inhospitable climate.
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Climate Migration. Human migration is an important climate change adaptation strategy, but there are many gaps in our understanding of the complex, multi-faced interaction between environmental ...
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In doing so, we consider new ways to connect the literature on climate change and migration to migration theory. Climate change is disruptive (Call et al. 2017). It disrupts processes that are already dynamic inasmuch as migration is related to life course transitions, evolving household strategies, and endogenous changes in social networks at ...
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The connection between climate change and migration - with or without conflict as a causal mediator - is by no means deterministic. Rather, it depends on a wide range of factors relating to considerations such as the vulnerability of the people and the region in question (Perch-Nielson et al., 2008).
Climate Change and Migration: An Overview for Policymakers and
The climate-migration nexus is complex. Climate change is having, and will have, multi-faceted impacts on a very wide range of issues. These will affect migration through direct and indirect pathways. Migration is multicausal, and while climate change will affect mobility choices, so too will many other factors.
Climate change and migration
Climate change and migration. Oscar A. Gómez. Published 30 November 2013. Environmental Science, Sociology. The present literature review aims to provide a panoramic view of the different ways in which the link between climate change and migration has been addressed in the existing literature, building on the recent non-annotated bibliography ...
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The protection of refugees is a fundamental part of the international community's mitment to sustainable development,49 and is a key policy concern when considering plan for future adaptation to climate change. Yet, the international policy framework on what should be done about climate change-related migration.
PDF Climate Change and Migration
Figure 1: Research on migration and climate change 17 Figure 2: Environmental change and drivers of migration 21 Figure 3: Mobility outcomes of environmental change 32 Figure 4: Disaster vs. conflict/violence -related internal displacement, 20082019 (in millions)- 34 Figure 5: Stock of internally displaced persons (IDPs) by cause of ...
Rapid evidence assessment on the impacts of climate change on migration
Policy papers and consultations. ... findings from 273 quantitative and qualitative studies published between 2005 and 2021 on the relationship between climate change and migration, with ...
Climate Change and Migration
Climate Change and Migration. A story that begins with case studies of small communities facing severe threats from climate change effects and continues with a look at large populations made vulnerable by human-induced changes to Earth's climate, leveraging data from a variety of sources such as academic journals and scientific agencies.
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As climate change affects countries, regions, and economic sectors in different ways, migration patterns will be altered and intensified. The World Bank's Groundswell report estimates up to 40 million climate migrants in South Asia alone by 2050, and a large body of literature suggests that climate change - and related disasters - are already ...
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The rapid anthropogenic climate change that is being experienced in the early twenty-first century is intimately entwined with the health and functioning of the biosphere. ... The papers in this section advance our thinking about the effects of climate change on ecosystem properties (biological diversity, trophic webs or energy flux, nutrient ...
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It contributes to a growing body of literature on migration in the context of climate and environmental changes,1 including movements affected by the slow- and sudden-onset impacts of climate change.
Global trends and scenarios for terrestrial biodiversity and ...
In addition, our projections assumed no species migration with climate change, whereas some models allowed for species migration or increased species richness in response to land-use change (table S2). Assumptions about dispersal can drive large differences in projections of climate change on biodiversity impacts . For instance, in the AIM ...
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3. Climate migration will be an economic decision, not an environmental one. Americans will ultimately respond to environmental change when it shows up as economic change. We are talking about a slow-moving change that will accelerate and unfold over decades, but we can see the signs now.
Immigration is surging, with big economic consequences
T he rich world is in the midst of an unprecedented migration boom. Last year 3.3m more people moved to America than left, almost four times typical levels in the 2010s. Canada took in 1.9m ...
Council Conclusions on Small Island Developing States (SIDS)
This Agreement is particularly relevant for SIDS, as almost all are members of the OACPS. It sets a high level of ambition for EU-OACPS cooperation on key common principles such as human rights, democracy, peace and security, human and social development, climate change and the environment, and migration and mobility.
As climate change pushes deer north, other animals may lose out
As winters warm, white-tailed deer push ever northward in North America. A recent study in Global Change Biology suggests that climate change is driving these habitat shifts — changes that may ...
Guatemala to host ministerial summit on migration and protection
Guatemala, May 7 (Prensa Latina) Guatemala will host a ministerial summit to address migration and protection, to be attended by ministers from 20 Latin American countries which signed the 2022 ...

How does climate change affect migration?

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What does the future hold for climate-related migration at the border? What should we expect, and how should we prepare for it?

How extensive is climate change’s effect on migration within the U.S.?

How might federal and state policy lessen climate change’s impact role as a driver of migration at the border and within the U.S.?

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