The relationship between global climate change and (US) immigration is analyzed in a July 26 Scientific American article by David Biello titled “Climate Change May Mean More Mexican Immigration.”
Analysis of data from 1995 to 2005 indicates that a 10% drop in crop yields (from drought) is correlated with an approximate 2% increase in Mexican migration to the USA. Climate change will also affect crop yields in the coming years and can also be expected, therefore, to influence migration rates. This is an interesting new perspective. Previously, most studies have focused on the relationship between migration and unemployment rates in the USA, as well as the importation of cheap corn from the USA under NAFTA.
Using data on predicted global warming and the relationship between temperature increase and reduction in crop yields, the study suggests the total number of climate refugees [see comment below] emigrating to the USA during the next 70 years could be 1.4 to 6.7 million, an average of about 20,000 to 96,000 per year. This is rather small compared to the estimated average of 460,000 net migrants per year from Mexico to the USA between 1995 and 2005.
Obviously, making such a long range forecast based on current data is risky for several reasons. First, predicted levels of global warming are uncertain. Second, new varieties of drought resistant corn and other crops may be developed. Third, the Mexican farming population is declining. Fourth, many of these climate refuges could end up in Mexican cities. Fifth, global warming may affect the number of available jobs in the USA.
Despite these limitations, the study is important because it adds to our understanding of the factors contributing to Mexican migration to the USA and provides a rational estimate of the impact of global warming on migration. The article by Biello is drawn from research published by Feng et al in the Proceedings of the National Academy of Sciences.
Mexican migration to the USA is the focus of chapter 26 of Geo-Mexico: the geography and dynamics of modern Mexico.