Drought as a driver of Mexico-US migration

Abstract

Emigration from Mexico to the USA represents one of the largest current socioeconomic phenomena in the world. Climate, and particularly drought, has been identified as a key driver of peak migratory flows between the two nations. However, current existing studies are constrained by a reduced spatial scale (e.g., a single community or municipality) or a short time-window (e.g. <10 years), which limits our long-term nationwide understanding of the climate-migration relationship. To tackle this, we employed high-resolution (municipal-level) and long-term databases (1970–2009), which included nation-level interviews, border patrol apprehensions, and high-resolution precipitation. Our results showed that the decadal and maximum migratory fluxes in these four decades corresponded to years with low precipitation. In particular, the migration of low-income rural farmers tripled during drought, representing as much as a third of all historical migration. It is very likely that rural people were pushed to leave their lands as the result of strongly diminished rainfed agriculture and pastureland production, their main livelihood. Our results suggest that policy oriented to reduce the negative impacts of drought (such as livestock drought insurances and the provisioning of drought-resistant seeds), particularly to marginal farmers in arid ecosystems, could be an effective way to reduce current and future migratory peaks between Mexico and the USA.