Population migration is typically explained through economic factors: job availability, housing costs, wage differentials. But a growing body of evidence suggests that climate is becoming a measurable driver of migration decisions, particularly in the United States where extreme heat, wildfire, drought, and flooding are intensifying unevenly across regions.
TerraFuture's research team has spent the past year analyzing IRS migration data, census records, real estate transaction data, and original survey research to quantify the climate signal in Pacific Northwest migration patterns. Our findings suggest that climate-motivated migration is not a future phenomenon. It is happening now, and its scale is growing.
The Data
Between 2020 and 2024, Oregon experienced net in-migration of approximately 148,000 people. Using IRS county-to-county migration data, we identified the origin states and counties for these new residents and cross-referenced that information with climate impact data including wildfire risk scores, extreme heat days, drought severity indices, and flood insurance claims.
The results show a clear pattern. Net in-migration from states classified as high climate-impact by the National Climate Assessment, including Arizona, Texas, California, Florida, and Louisiana, increased 23 percent over the 2020-2024 period compared to 2015-2019. By contrast, in-migration from low-impact states remained essentially flat, growing just 2.1 percent.
The origin counties with the highest net out-migration to Oregon were disproportionately those with the most severe climate indicators. Counties in the top decile for extreme heat days sent 3.4 times more migrants to Oregon per capita than counties in the bottom decile.
Survey Evidence
To complement the migration data, we conducted a survey of 1,200 recent Oregon transplants who moved from high-impact states between 2021 and 2024. Among respondents, 42 percent cited climate or weather conditions as a factor in their decision to relocate. Eighteen percent identified climate as the primary factor.
The most commonly cited climate concerns were extreme heat at 61 percent, wildfire smoke and risk at 54 percent, water scarcity at 38 percent, and hurricane and flooding risk at 27 percent. Notably, respondents who cited climate as a factor were significantly more likely to be between the ages of 25 and 44 and to have children under 18, suggesting that climate migration decisions are often family-driven.
Climate migration is not a single dramatic event. It is a gradual shift in where people choose to build their lives, driven by a rational assessment of which places will remain livable in the decades ahead.
Implications for the Pacific Northwest
If current trends continue, our projections suggest that climate-motivated in-migration could add 35,000 to 55,000 additional residents to Oregon over the next decade beyond baseline demographic projections. Portland and the Willamette Valley would absorb approximately 60 percent of that growth.
This has significant implications across multiple domains. Housing demand in an already-constrained market will intensify. Portland's housing deficit, currently estimated at 24,000 units by the Home Builders Association of Metropolitan Portland, could grow by 8,000 to 12,000 additional units due to climate migration alone.
Water systems designed for a smaller population will face increased pressure. The Portland Water Bureau's supply system, sourced from the Bull Run watershed and the Columbia South Shore Well Field, currently serves 1 million people and is designed for a population of 1.3 million. Climate migration could accelerate the timeline for reaching that capacity by 5 to 10 years.
Transportation, schools, healthcare systems, and social services will all face demand increases that are not captured in current planning assumptions.
The Equity Dimension
Climate migration is not socioeconomically uniform. Higher-income households have greater capacity to relocate proactively, while lower-income households are more likely to move reactively after a climate disaster. Our survey data shows that climate migrants to Oregon have a median household income 18 percent higher than the state median, suggesting that early-stage climate migration is amplifying existing economic disparities.
Meanwhile, the communities that climate migrants leave behind become less resilient as tax base, social capital, and working-age population decline. This creates a feedback loop that is difficult to reverse.
Planning Ahead
TerraFuture is calling on regional planning agencies to incorporate climate migration projections into their long-range planning documents. We are providing our dataset and methodology to Metro, Portland's regional government, for integration into the 2024 Urban Growth Report.
We are also developing a Climate Migration Readiness Index that assesses community capacity to absorb population growth across dimensions including housing, water, transportation, and social services. Communities that plan proactively for climate-driven growth will be better positioned to maintain livability and equity as the population shifts continue.
The full dataset and methodology are available on our Open Climate Data Portal. We encourage researchers, planners, and community organizations to use this data in their own work. Contact our research team to discuss collaboration opportunities.
