In southwestern France, at least 12 people are dead after a powerful storm brought the equivalent of seven months’ worth of rain in just a few hours, flooding whole villages and forcing authorities to evacuate residents trapped on rooftops. The floods are the worst to hit the area in over a century. They came as meteorologists said exceptionally warm sea water along the Mediterranean coast added to the storm’s ferocity. The increased ocean temperatures are consistent with global warming caused by human activity.