In the long sweep of human history, water has always played a central role in determining the geography of civilizations, and eons ago it influenced the migration of our early ancestors out of Africa and across the world. The ability to manage water contributed to the success or failure of empires along the Tigris and Euphrates rivers of the Middle East, the Indus in southern Asia, and the Yangtze in China. This First Age of water saw the earliest efforts to manipulate water with dams, aqueducts and intentional irrigation, and also the first water laws, institutions and water conflicts.
As human populations and economies outgrew local water resources, a new age led to revolutions in science, engineering, medicine and knowledge. During this Second Age of water, we uncovered the chemical, physical and biological nature of water, improved our ability to understand and control the hydrologic cycle, learned about the causes and cures for water-related diseases and built the agricultural systems that let us feed and support today’s 8 billion people. We now have the technology to produce the cleanest water from the most contaminated, purify and recycle water to support astronauts on the space station and launch instruments and robotic explorers into the far reaches of the solar system, often looking for water.
But this second age has also led to unintended consequences: the overuse and contamination of rivers, lakes, groundwater and oceans; worsening inequality of resource use; the destruction of aquatic ecosystems; and climate change, which affects the waters of the planet.
