Income strongly moderates climate-driven migration

Gaurav Khanna, Pascal Polonik, Jessica Wan, Jacopo Lunghi, Idaliya Grigoryeva, Katharine Ricke

Understanding how climate change will reshape human migration remains an open empirical challenge. Migration decisions reflect a complex interplay of environmental and socioeconomic factors, yet existing data and models have struggled to capture this interaction at a global scale. To address this, we assemble spatially granular, long-panel migration data covering nearly the entire world and develop a statistical model that captures how both climate and income dynamics shape rural-to-urban migration responses. Using this new approach, we uncover a strong and robust dependence of climate-driven migration on income levels, as well as a nonlinear relationship between internal migration and climate. We then use these relationships, together with international migration data, to project how migration pressures will be shaped by the interaction between warming and income growth. Our findings show that the magnitude and geography of climate-induced migration will depend critically on how quickly incomes rise across the world.