Beginning in the 17th century, centers of wealth and power emerged in a narrow band of northern latitudes where mild weather put minimal stress on urban and industrial infrastructure. These societies were able to grow their local populations faster than the rest of the world and expand their reach, often by exploiting other lands and people.
By the 1950s, there were 2.5 billion people on Earth, and most lived in moderate climates. Since then, however, the distribution of the world’s population has shifted. We will pass 8 billion people in 2023, and the majority will live in places with more challenging climates. Climate change is reshaping both local precipitation patterns and the global water system—and everyone on Earth will be affected.