Adapting to Climate Risk? Local Population Dynamics in the United States

Abstract Using a new composite climate-risk index, we show that population in high-risk counties has grown disproportionately over the last few decades, even relative to the corresponding commuting zone. We also find that the agglomeration is largely driven by increases in the (white) working-age population. In addition, we show that high-risk tracts have typically grown more than low-risk tracts within the same county, suggesting the presence of highly localized amenities. We also document heterogeneous population dynamics by degree of urbanization, region and type of natural hazard. Specifically, population has been retreating from high-risk, low-urbanization locations, but continues to grow in high-risk areas with high residential capital. Net migration flows have contributed to the higher growth of high-risk counties in the South and Northeast of the country, but the opposite has happened in the West and Midwest. Last, we provide evidence of microretreat in the case of coastal flooding : tracts with high levels of this risk have grown significantly less than other tracts in the same county, suggesting that residents are willing to relocate within short distances to avoid predictably risky locations.