How Climate Change and Fertility Rates Are Linked

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01/20/2020 10:23

How Climate Change and Fertility Rates Are Linked

Katrina Jordan Abteilung Kommunikation
Universität Passau

    Why is the demographic transition in Sub-Saharan Africa faltering? Professor Michael Grimm, development economist at the University of Passau, uses historical data from the USA to show why climate change could increase the fertility rate in poor rural regions.

    In poor rural areas, children not only provide old-age security, but also fulfil an insurance role against rainfall risks or risks of drought such as crop failures. This is the conclusion reached by Professor Michael Grimm, Chair of Development Economics at the University of Passau, in a study on the demographic transition in the USA in the late 19th and early 20th century. The phenomenon and theory of the "demographic transition" refers to the historical shift in demographics from high birth rates and high infant death rates to demographics of low birth rates and low death rates.

    "My analysis shows that farm households in counties with strong rainfall variability had more children than in regions with less severe weather fluctuations.” By engaging in household chores, children allow older family members to spend more time working in the fields or in the non-agricultural sector. Once they have grown up, children can also directly contribute to earning an income in hard times.

    The study included 945,038 observations from historical census data on women between the ages of 15 and 39 as well as historical weather records and data on agriculture and banking. The effect that strong rainfall risks or risks of drought are a driver of fertility is robust to a wide range of controls such as potential structural differences between areas with higher and lower levels of rainfall variability.

    The insurance function of children is decreasing with the emergence of irrigation systems, modern agricultural machinery and financial services. In connection with irrigation systems, the development economist was able to determine the greatest effect: The fertility differential due to rainfall variability disappears if the share of irrigated land in a county exceeds 23 per cent. Irrigation systems meant that the farms no longer had to fear being helplessly exposed to the risk of damage, for example from droughts. A significant effect could also be observed where more machinery was used.

    Parallels with the situation in sub-Saharan Africa

    Prof. Dr. Grimm focuses his research on the poorest regions of Africa. For the time around the late 19th and early 20th century, he sees many parallels in the USA with the situation in some regions of Sub-Saharan Africa, where demographic transition is currently faltering: "A large proportion of US households were active in agriculture, especially those settlers who spread to the West. There were no machines, the capital stock was zero. In many regions, there were strong weather fluctuations with changing periods of too little or too much rain", says Professor Grimm.

    From Prof. Dr. Grimm's point of view, the historical data provides important insights for current development policy challenges: Climate change increases the risk of extreme weather conditions, which in turn could explain why the demographic transition in some regions of sub-Saharan Africa has come to a halt. "In order to accelerate demographic change, future measures must not only bring about structural change towards a modern economy, but must also take particular account of the aspect of security, for example in the form of health insurance or social security networks", says Professor Grimm.
    The study is published in the renowned American “Journal of Economic Geography”.

    Editors: Please address your enquiries to the Media Relations Section, phone: +49 851 509 1439.

    Contact for scientific information:

    Professor Michael Grimm,

    Original publication:

    Link to the original study -

    Criteria of this press release:
    Economics / business administration, Environment / ecology, Nutrition / healthcare / nursing, Social studies
    transregional, national
    Research results


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