New research shows that by 2050 an additional 1 billion people will live in areas with high levels of water stress. See where water is scarcest in the world — and why we need to conserve.

Disregard what you learned in geography class—Earth may not have seven continents after all. From the earliest of grades, schoolchildren around the world have memorized the same lineup: Africa ...

A hiker and outdoorsman, Mr. Thomas as a child yearned for a world where nature ruled supreme. His map represents the “idealistic planet that I wanted,” Mr. Thomas, 34, said.