National Geographic: In So Paulo, Brazil, which is suffering its worst drought in almost a century, Maria de Fátima dos Santos has lived for days at a time with no water, relying on what she had carefully hoarded in bottles. But in the Bolivian Amazon, about 1,800 miles (2,897 kilometers) away, Nicolás Cartagena recalls the day almost a year ago when floodwaters rose to the thatched rooftops of Indian communities, destroying crops and washing away homes. The drought in South America's biggest city and the flooding...