Climatic shocks and human mobility: Exploring the effect of rainfall on internal migration patterns in Peru

The present research studies the relationship between rainfall occurring during the rainy season (December to March) and internal migration patterns in Peru for the period 20072010. Specifically, it considers inter-province and intra-province migration indicators, and the rural population rate as a “proxy” for rural-to-urban migration. It employs a province-level panel data set built from the National Household Survey (ENAHO) conducted by the Statistics Bureau of Peru and georeferenced climate data from the Climatic Research Unit of the University of East Anglia (CRU TS 4.07). The findings indicate a significant quadratic negative relationship between the inter-province immigration rate and precipitation, demonstrating an inverted “U” shape with a critical threshold at 1,070 millimeters. Beyond this point, the immigration rate starts to decline. Furthermore, the study explores the influence of unexpected precipitation shocks, revealing that both negative (less or equal than -0.75 standard deviations) and positive (greater or equal than 0.75 standard deviations) shocks significantly affect the immigration rate and the rural population rate. These critical points appear as pivotal thresholds, beyond which the effects become perceptible. In assessing precipitation-related disasters -specifically landslides, floods, and farmland loss/damage- the study shows no statistically significant relationship for the overall sample. However, when examining geographical variations, coastal provinces exhibit a positive relationship between the emigration rate and rainfall, when the threshold of 504-615 millimeters is surpassed. Conversely, the Amazon experiences a 3-percentage point increase in the immigration rate for every 10-percentage point increase in rurality. Additionally, emigration increases by 1 percentage point for each 1,000-hectares loss/damage of cropland. This research provides valuable insights into the role of precipitation in shaping internal migration patterns in Peru, emphasizing the need for nuanced regional analysis to fully comprehend the diverse effects considering the geographic particularities within the country.