Exposure to drought in early life raises the chances that an individual will have a physical disability in later life. That is the central finding of research on South Africa by Professor Taryn Dinkelman, published in the September 2017 issue of the Economic Journal. Her study reveals that the lingering effects of natural disasters on health are most pronounced for men.

Over the last 30 years, droughts in Africa have affected three times more people than all other natural disasters combined. Professor Dinkelman''s research shows that the human consequences of these droughts are long-lasting.

By linking droughts today with disability rates in the future, her work suggests that the burden of disability in low-income countries is likely to grow. This is particularly worrying given the likelihood that climate change will increase the frequency and intensity of droughts, as well as the fact that roughly one in five of the world''s poorest people already have some type of disability.

Professor Dinkelman comments:

''Any increases in disability rates that stem from exposure to harsh environmental conditions in early life may in turn significantly undermine labour productivity in African countries – unless policy-makers are willing to put in place adequate mitigation strategies.''

The new study takes place in the unique context of South Africa during apartheid, when black South Africans were forced to live in specified geographical regions. These regions were poorly suited to farming, making it difficult for families to maintain adequate nutrition during droughts.

Professor Dinkelman links 40 years of weather data on where and when droughts happened in these regions to the disability rates of people born in different regions and different years. Using census data, she documents that 7% of Africans were born during a drought and that this group spent (on average) 6.2% of their first five years of life exposed to a local drought.

After accounting for the fact that people born in different regions and different periods may have different underlying disability rates (for example, because medical interventions improve over time), Professor Dinkelman finds that being exposed to the average level of drought in the first five years of life raises disability rates by between 3.5% and 5.2%.

These effects are largest for men, and largest for physical and mental disabilities. Consistent with previous research showing that male foetuses and babies are generally more fragile and sensitive to nutritional insults, the new study finds that the negative effects on disability are 40% larger for men than for women.

Professor Dinkelman shows that the impacts of drought on later-life disability are worst for people born in areas where legal restrictions on migration were the most stringent. Investigating the role of migration restrictions further, she finds that when migration restrictions fell away in the later years of apartheid, drought exposure no longer increased disability rates.

Her analysis suggests that policies that facilitate migration may have enabled families to cope better with local droughts by relying on financial resources sent by household migrants.

''Long-run Health Repercussions of Drought Shocks: Evidence from South African Homelands'' by Taryn Dinkelman is published in the September 2017 issue of the Economic Journal. Taryn Dinkelman is at Dartmouth College.