Extreme weather is contributing to undocumented migration and return between Mexico and the United States, suggesting that more migrants could risk their lives crossing the border as climate change fuels droughts, storms and other hardships, according to a new study. Extreme weather is contributing to undocumented migration and return between Mexico and the United States, suggesting that more migrants could risk their lives crossing the border as climate change fuels droughts, storms and other hardships, according to a new study. Environment Phys.org – latest science and technology news stories