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.
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, according to a study published online this week in the Proceedings of the National Academy of Sciences. 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.
"Our primary objectives were, No. 1, to give policymakers something to think about and, No. 2, to give researchers a spur to start answering some of the more complicated questions," he said.