NCPA - National Center for Policy Analysis


August 2, 2010

Climbing temperatures are expected to raise sea levels and increase droughts, floods, heat waves and wildfires.  Now, scientists are predicting another consequence of climate change -- mass migration to the United States. 

According to a study published online this week in the Proceedings of the National Academy of Sciences: 

  • Between 1.4 million and 6.7 million Mexicans could migrate to the United States by 2080 as climate change reduces crop yields and agricultural production in Mexico.
  • The number could amount to 10 percent of the current population of Mexicans ages 15 to 65. 

"Assuming that the climate projections are correct, gradually over the next several decades heading toward the end of the century, it becomes one of the more important factors in driving Mexicans across the border, all other things being equal," said study author Michael Oppenheimer, professor of geosciences and international affairs at Princeton University. 

Of course, Oppenheimer acknowledged, all things will not remain equal.  Changes could occur in U.S. immigration and border policy, or in Mexico's economy and its reliance on agriculture.  But he said this was a simplified first step in studying the effect of global warming on migration. 

Oppenheimer teamed up with two economists, Alan B. Krueger and Shuaizhang Feng, to study the connection between agricultural decline and migration.  They looked at Mexican emigration, crop yield and climate data from 1995 to 2005 to make estimates about the next 70 years. 

In the past, Oppenheimer said, Mexican farmers from rural areas fled to the United States when they could no longer grow their crops.  If the rising temperatures dry out the land and reduce yield as expected, many more farmers could do the same. 

Source:  Anna Gorman, "New incentive to fortify the border? Climate change linked to mass Mexican migration to U.S.," Jewish World Review, July 27, 2010. 

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