Department of Economics, San Diego State University, San Diego, CA 92182.
Charles H. Dyson School of Applied Economics and Management, Cornell University, Ithaca, NY 14853.
Proc Natl Acad Sci U S A. 2024 Nov 12;121(46):e2400524121. doi: 10.1073/pnas.2400524121. Epub 2024 Nov 4.
As the world's climate continues to change, human populations are exposed to increasingly severe and extreme weather conditions that can promote migration. Here, we examine how extreme weather influences the likelihood of undocumented migration and return between Mexico and the United States. We used data from 48,313 individuals observed between 1992 and 2018 in 84 Mexican agricultural communities. While controlling for regional and temporal confounding factors, we related individual decisions to migrate to the United States without documents and subsequently return to Mexico with lagged weather deviations from the historical norm during the corn-growing season (May to August). Undocumented migration was most likely from areas experiencing extreme drought, and migrants were less likely to return to their communities of origin when extreme weather persisted. These findings establish the role of weather shocks in undocumented Mexican migration to, and eventual settlement in, the United States. The findings also suggest that extreme weather conditions, which are likely to increase with climate change, promote clandestine mobility across borders and, thus, expose migrants to risks associated with crossing dangerous terrain and relying upon smugglers.
随着世界气候持续变化，人类面临着越来越严峻和极端的天气条件，这可能会促使人口迁移。在这里，我们研究了极端天气如何影响墨西哥和美国之间无证移民的可能性及其回流。我们使用了 1992 年至 2018 年间在 84 个墨西哥农业社区中观察到的 48313 个人的数据。在控制了区域和时间混杂因素的情况下，我们将个人前往美国无证移民的决定与玉米种植季节（5 月至 8 月）期间历史常态的滞后天气偏差相关联。无证移民最有可能来自经历极端干旱的地区，而当极端天气持续时，移民返回原籍社区的可能性就会降低。这些发现确立了天气冲击在墨西哥无证移民向美国迁移并最终定居的作用。这些发现还表明，随着气候变化，极端天气条件可能会增加，跨境秘密流动增加，从而使移民面临穿越危险地形和依赖走私者的风险。
