Dramatic and spontaneous natural disasters garner substantial humanitarian aid—as they should. But long-term chronic environmental pressures such as heat stress also put tremendous strain on rural households, especially households in less developed countries that rely on agriculture.
People migrate in response to immediate disasters as well as to longer-term environmental strains. Humanitarian aid can potentially reduce the need for both kinds of migration.
Migration From Environmental Stress
Environmental factors have always shaped migration. In the ancient Sahara, archaeological and anthropological evidence suggest that humans migrated as shifts in the monsoon patterns allowed them to move deeper into the desert. Alternatively, periods of droughts forced people to leave the desert in search of water and pasture land for their animals—much like contemporary nomadic populations.1
More recent examples are also useful. The dust bowl in the United States from 1931 to 1939 led to massive soil erosion and a drastic reduction in soil productivity. Billowing clouds of dust buried farm equipment and buildings. Hundreds of thousands of residents had no choice but to leave the Great Plains.2
Humanitarian Aid and Migration
Today, environmental catastrophes fill the news. Typhoon Haiyan devastated the Philippines in November 2013; and a massive tornado carved a 12-mile path through Oklahoma City in May 2013. Over $4 billion are spent on emergency relief for natural disasters every year.3 But dramatic environmental disasters aren’t the only reasons people migrate.
Comparing Floods and Heat Stress in Pakistan
To shed light on migration in the face of different environmental challenges, a recent study in Nature Climate Change focused on rural Pakistan over a 21-year period. The migration histories of over 4,000 individuals between 1991 and 2012 were examined by researchers Valerie Mueller from the International Food Policy Research Institute, and Clark Gray and Katrina Kosec from the University of North Carolina’s Population Center. They linked rainfall and temperature data with migration data.
Their research found that heat stress rather than floods was most related to migration. Heat stress in rural Pakistan is intense during the wheat-growing season, from winter to spring. Also, poor households tended to move longer distances, suggesting that migration is important as an adaptive response, especially among the most vulnerable populations.4
Environmental Pressures Act on a Continuum
Research in other regions has also documented the migratory impact of long-term chronic environmental stress. In dry rural regions of Mexico, migration to the United States increases in times of low rainfall.5 In India, a severe drought in 2003 led nearly all households in the small village of Khaliakani to send at least one migrant in search of income elsewhere.6
An environmental driver of migration, drought, as a longer-term chronic stress, is at one end of a continuum. Sudden catastrophic events are at the other end. In the case of chronic long-term migration, a family may not move but will send someone from the household to seek labor elsewhere and send remittances home. On the other hand, acute and sudden natural disasters may result in refugee streams, although relocation may be short term.
Difference Pressures Require Different Policies
Humanitarian aid in the wake of natural disasters is essential. Yet the impacts on rural livelihoods of longer-term environmental pressures should also be recognized. Sustainable development requires policies and programs to help rural residents adapt to weather-related risks. Such responses might include capturing rainfall for irrigation (“rainwater harvesting”), using heat-resistant seed varieties, providing agricultural insurance, and improving weather forecasting.