"The World Bank predicts climate change could create as many as 143 million 'climate migrants' by 2050. The result would be a mass migration twice as large as the number of refugees in the world today.

Though the size of potential displacement is unprecedented, the relationship between migration and climate has played out on a smaller scale throughout the history of North America, say historians Nathan Connolly and Ed Ayers.

Connolly, a professor at Johns Hopkins University, points to long-lasting droughts from the 12th and 13th centuries that caused relocations of indigenous communities in the American West. Archaeological records show periods of drought that lasted decades, starting as early as the 11th century."

Francesca Paris reports for NPR October 20, 2018. [2]