Summary Points

• Most people displaced by climate change stay within their country’s borders, but cross-border migration is increasing.
• Migration decisions are typically influenced through economic, political, social, demographic, and environmental channels.
• There is no coordinated system to track long-term climate migration.
• Stronger policies and improved long-term forecasting are essential to address climate migration amid uncertain future conditions.

Growing Migration Induced by Climate Change

The World Bank estimates that by 2050 climate change could lead more than 216 million people across six global regions to migrate within their own countries, due to issues including water scarcity, decreased crop productivity, sea level rise, heat stress, extreme events, land loss, and more.¹ In 2024 alone, there were 45.8 million internal displacements of people due to disasters across 211 countries and territories, led by storms, flooding, earthquakes, drought, and wildfire.²

In 2021, the White House published a “Report on the Impact of Climate Change on Migration.”³ Citing the UN High Commissioner for Refugees Global Trends Report, they highlight the acceleration of cross-border movement:

“Although most people displaced or migrating as a result of climate impacts are staying within their countries of origin, the accelerating trend of global displacement related to climate impacts is increasing cross-border movements, too, particularly where climate change interacts with conflict and violence.”

Professor Barbara F. Walter’s research demonstrates how climate-induced resource scarcity and economic strain can lead to social instability and conflicts.

Professor Hélène Benveniste’s research shows that migration decisions are typically influenced both directly and indirectly through economic, political, social, demographic, and environmental channels. While migration serves as an adaptation option for those seeking better employment, health, and living conditions, climate change creates a paradox: the most vulnerable populations often lack the resources to move away from increasingly at-risk areas, trapping them in harm’s way.

Climate Migration in the US and California

Focusing on the U.S., Professor Joshua Busby examines how climate change may affect domestic security interests. He identifies four main risks for the United States:

1. Threats to overseas assets such as embassies and military bases
2. Increased likelihood of violent conflict
3. Potential for state failure
4. The rise of humanitarian crises

Migration—regardless of whether it leads to conflict—is often cited as a distinct climate-related security concern.

For Californians, catastrophic wildfires have put climate migration front and center, forcing key decisions amid an already strained housing supply—and affecting the communities where displaced residents resettle. Studying displacement from the Camp Fire, Chico State researcher Peter Hansen showed that while many residents resettled within California, they also settled across the country (Figure 1), with those 65 and older more likely to move further away.⁴,⁵

The Urban Institute, supported by the National Academy of Sciences Gulf Research Program, assessed the capacity of communities that receive climate migrants, offering recommendations across five reports.⁶ Separately, they also assessed rebuilding metrics for the LA wildfires, comparing to the Carr, Camp, Marshall, and Maui Fires.⁷

In California, 25% consider climate change a major reason that people immigrate to the US.⁸ An upcoming study on Climate-Induced Human Migration and Displacement in California, conducted as part of California’s Fifth Climate Change Assessment, will shed light on the impacts of climate disasters for California.⁹

<sup>1. World Bank (2021). Groundswell: Part 2.↩
2. Internal Displacement Monitoring Centre. (2025). Global internal displacement database.↩
3. The White House. (2021, October). Report on the impact of climate change on migration.↩
4. California State University, Chico. (2019). Mapping a displaced population.↩
5. Think Global Health. (2024). Move: How climate migration will remake America.↩
6. Urban Institute. (2023). Climate migration and receiving community institutional capacity: US Gulf Coast.↩
7. Urban Institute. (2025). When will Los Angeles rebuild?: Comparing housing recovery timelines after four recent disasters.↩
8. UC Berkeley. (2024). More Californians recognize climate change caused mostly by human activities.↩
9. UC Berkeley Human Rights Center. (2025). California report on climate-induced human migration and displacement.↩</sup>

About CCST
The California Council on Science and Technology is a nonpartisan, nonprofit organization that engages leading experts in science and technology to advise State policymakers — ensuring that California policy is strengthened and informed by scientific knowledge, research, and innovation. Established via a unanimous vote of the California State Legislature, CCST has been making California’s policies stronger with science and technology since 1988.

Disaster Resilience Initiative
CCST’s Disaster Resilience Initiative is generously supported by the State of California through a one-time funding allocation in the 2021-2022 State budget. This allocation supports the transmission of information between science and technology experts and policymakers focused on the overlapping, intersecting, and compounding nature of disasters in California.

Acknowledgements

Contributors: Lyia Jalao, Eric Chu, John Thompson, Mikel Shybut
Editor: Mikel Shybut, PhD, Science Communications and Content Manager

CCST Contacts:

• John Thompson, PhD, Science Services Manager ([email protected])
• Puneet Bhullar, MPPA, Director of Policy Engagement ([email protected])

Partner Contacts

• Nico Pascal, PhD, UC Disaster Resilience Network ([email protected])
• Angelina Soldatos, Institute for Security and Governance ([email protected])