Mueller Valerie, Gray Clark, Hopping Douglas
School of Politics and Global Studies, Arizona State University, PO Box 873902, Tempe, AZ 85297-3902, USA.
International Food Policy Research Institute, 1201 Eye Street, NW, Washington, DC 20005-3915, USA.
Glob Environ Change. 2020 Nov;65. doi: 10.1016/j.gloenvcha.2020.102183. Epub 2020 Oct 10.
One of the major unresolved questions in the study of vulnerability to climate change is how human migration will respond in low and middle-income countries. The present study directly addresses this lacuna by using census data on migration from 4 million individuals from three middle-income African countries over a 22-year period. We link these individuals to climate exposures in their origins and estimate climatic effects on migration using a fixed-effects regression model. We show that climate anomalies affect mobility in all three countries. Specifically, mobility declines by 19% with a 1-standard deviation increase in temperature in Botswana. Equivalent changes in precipitation cause declines in migration in Botswana (11%) and Kenya (10%), and increases in migration in Zambia (24%). The mechanisms underlying these effects appear to differ by country. Negative associations between precipitation anomalies, unemployment, and inactivity suggest migration declines may be due to an increased local demand for workers to offset production risk, while migration increases may be indicative of new opportunities in destinations. These country-specific findings highlight the contextually-specific nature of climate-migration relationships, and do not support claims that climate change is widely contributing to urbanization across Africa.
气候变化脆弱性研究中一个主要未解决的问题是,中低收入国家的人口迁移将如何应对。本研究通过使用来自三个非洲中等收入国家400万人在22年期间的人口普查迁移数据,直接填补了这一空白。我们将这些人与他们原籍地的气候暴露情况联系起来,并使用固定效应回归模型估计气候对迁移的影响。我们发现,气候异常影响了所有这三个国家的人口流动。具体而言,在博茨瓦纳,温度每增加1个标准差,人口流动率就下降19%。降水量的同等变化导致博茨瓦纳(11%)和肯尼亚(10%)的迁移率下降,而赞比亚的迁移率上升(24%)。这些影响背后的机制似乎因国家而异。降水异常、失业率和不活动率之间的负相关表明,迁移率下降可能是由于当地对工人的需求增加,以抵消生产风险,而迁移率上升可能表明目的地有新的机会。这些特定国家的研究结果凸显了气候与迁移关系的背景特异性,并不支持气候变化广泛推动非洲城市化的说法。