Climate change and its impacts — rising seas that lead to land loss, for example, and sustained droughts that make it harder to grow crops in certain areas — are influencing where people live and whether they move.

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.

Some speakers at the workshop explained what research has revealed so far, not all of which has reached broader awareness. “International migration grabs a lot of the headlines, but internal migration is way more common,” said Deborah Balk, who directs the Institute for Demographic Research at the City University of New York. “And it is definitely where we will see most of the migration that results from climate stress and weather events.”

Giuliano Di Baldassarre, who spoke about the impact of floods and droughts on human migration, noted this as well. “Climate-related mobility … rarely involves crossing borders,” said Di Baldassarre, a professor of hydrology and environmental analysis at Uppsala University in Sweden. “When we speak about migration in relation to extreme events … this often consists of short-term, local, and/or rural-to-urban migration.” However, not everyone who wants to move has the resources to do so, he added. “The social groups that are most vulnerable to the impacts of climate change are often also unable to move.”

Some speakers presented their own research on migration in particular regions. Serena Ceola of the University of Bologna spoke about the relationship between human settlement patterns in Africa and droughts, which have become more intense, frequent, and widespread on the continent over the past 50 years. Analyzing data from 50 African countries from 1992 to 2013, she and her colleagues found that during drought years, there was increased human displacement toward rivers and urban centers.

“The majority of African countries experienced this,” said Ceola. “This is extremely important, because if there is an increased population in flood plain areas that is taking place during droughts … then if a flood is occurring afterwards, you can imagine the fatalities and the losses that could occur.”

Nina Lam, professor of environmental science at Louisiana University, has studied climate migration in southeastern Louisiana. She surveyed residents to try to understand the factors people consider as they decide whether to relocate in the face of flood risk. The survey revealed economic opportunities as the highest-priority factor — greater than flooding — as people considered whether to move. For relocation to be workable, it “must come with having some economic opportunities available at the new locations,” said Lam.

The complexity of modeling

“When people ask us to think about the future of climate-related migration, it’s tough — because modeling this is tough,” said Lori Hunter, a professor of sociology at the University of Colorado, Boulder.

Part of the challenge springs from the many drivers of migration, which is a complex social process shaped by factors ranging from individuals’ age and ethnicity to social networks to political and economic conditions, Hunter explained. Environmental influences interact with these other elements to shape decisions about migration, such as environmental changes that affect economic opportunities.

People’s responses to climate-related threats are also complex, explained Cristina Cattaneo, who heads research on climate migration for the European Institute on Economics and the Environment. Some projections of future migration are based on estimating the number of people exposed to a particular climate risk. “But we know that being exposed to a climate hazard doesn’t necessarily imply that people decide to move,” said Cattaneo. “There are alternative forms of adaptations” — such as switching occupations, planting a different crop, or purchasing insurance. Sometimes migration is the last-resort solution, she said.

Gaps in data complicate efforts to model and project climate migration as well. Justin Mankin, a professor of geography at Dartmouth College, explained how “data poverty” — a lack of both social and physical data — can reflect and perpetuate inequities. For example, global meteorological stations have data gaps that map to the most vulnerable populations, he said; North America and Europe have plenty of weather data, but Africa, South America, and parts of the Middle East and South Asia have far less.

“We are systematically underestimating the impacts and costs of climate inaction,” said Mankin. “We are unable to track climate impacts for the areas that are least culpable for them, are experiencing them first, and have the fewest resources to manage them. And we have the least data to even articulate what those impacts are and therefore help them develop management strategies.”

The importance of Indigenous knowledge

Multiple speakers stressed the need to incorporate qualitative insights, oral histories, and local and Indigenous knowledge into research on climate migration.

Among them was Jackie Qatalina Schaeffer, who spoke about the value of Alaska Natives’ knowledge of their environment and how they are being affected by a changing climate. Schaeffer, who is Inupiaq and was raised on northern coast of Alaska, serves as director of climate initiatives for the Alaska Native Tribal Health Consortium.

Schaeffer said that while historically tribes had migrated seasonally with their food systems, the U.S. government forced the communities to stay on the lands they exist on now, which are along the coast or river systems. “Every community was placed on fragile ground,” said Schaeffer.

Schaeffer’s ancestors have been in the Arctic for 10,000 years — yielding historical knowledge whose value she sees firsthand when she visits villages and speaks with elders. “They have intimate knowledge of ice systems, and those ice systems are a trigger for the rest of the ecological systems — that’s what changes the water levels, the temperatures, the weather cycles,” she said.

Similarly, Meda Dewitt of the Wilderness Society shared a story that has been transmitted through thousands of years about the experiences of the Tlingit people with climate change and its impacts. “As we move forward, these stories or traditional ecological knowledge help give us guidelines.”

During policy and economic discussions, however, such groups are often out of sight and out of mind, said Schaeffer. “Most vulnerable populations don’t get the opportunity to sit in spaces like this and share this.” She urged the audience to keep in mind that impactful oral histories are an important and effective way to connect different sectors and cross-pollinate siloed systems.

The workshop was part of a series of follow-on activities based on the National Academies report Next Generation Earth Systems Science at the National Science Foundation, which was released in 2021.