Alexandre Gori Maia (UNICAMP) and Stella Zucchetti Schons (Virginia Tech) analyzed the impacts of the main extreme and gradual environmental changes on migration flows in the Brazilian Amazon. Gradual changes include historical changes in deforestation, temperature, and precipitation. Extreme changes include unexpected temperature and precipitation events. The authors show how environmental change has accelerated to the current and growing process of urbanization in the Brazilian Amazon. The paper has been recently published in the journal Population and Environment.

Brazil presents the largest Amazon region population – nearly 17 million people in 2010. Migration flows nowadays in the Brazilian Amazon are primarily characterized by the rural-urban shift of population. With nearly three-thirds of the people living in urban areas, the region presents one of the highest rates of internal migration in Brazil: roughly 10% of the population migrated between 2005 and 2010. Environmental changes, such as widespread deforestation, forest fires, and increasing temperatures may affect migration flows, for example, by affecting the quality of life and the dynamics of the agricultural activity.

One main empirical challenge of this study was to disentangle the complex connections between deforestation of rainforest ecosystems, climate change, and economic and population dynamics measured at the municipality level. The study proposes an empirical strategy that combines macro-level gravity models, zero-inflated models, and instrumental variable estimators. This strategy was able to account for regional push and pull factors, to tackle the large proportion of zero migration flows between the pairs of municipalities, and to control for potential sources of endogeneity in the deforestation variable. 

One main theoretical contribution of this study was to analyze three main hypotheses linking environmental changes to out-migration flows in the Brazilian Amazon: (i) the life cycle channel (the stage of demographic development); (ii) the agricultural productivity channel (land productivity and agricultural dynamics); (iii) the amenity channel (climate-related amenities that retain people in the region). 

The authors found strong evidence that out-migration is mainly affected by changes in the share of deforested land of sending localities. This result is partially linked to the life cycle channel, i.e., the old frontier of colonization is left to an aging population, while a younger generation advances further into the frontier or migrate to nearby urban centers. Moreover, the association between out-migration and environmental change is larger in the case of rural out-migration and intra-regional migration, which may accelerate the process of urbanization in the Amazon region.