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.

中文翻译：

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与墨西哥和美国之间的无证移民和返回有关的天气偏差


随着世界气候的不断变化，人类暴露在日益恶劣和极端的天气条件下，这可能会促进移民。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和返回的可能性。我们使用了 1992 年至 2018 年间在墨西哥 84 个农业社区观察到的 48,313 人的数据。在控制区域和时间混杂因素的同时，我们将个人决定与没有证件移民到美国，随后在玉米生长季节（5 月至 8 月）期间因天气滞后而返回墨西哥而返回墨西哥。无证移民很可能来自经历极端干旱的地区，当极端天气持续时，移民不太可能返回原籍社区。这些发现确定了天气冲击在无证墨西哥人迁移到美国并最终在美国定居中的作用。研究结果还表明，极端天气条件可能会随着气候变化而加剧，这促进了跨境秘密流动，从而使移民面临与穿越危险地形和依赖走私者相关的风险。