Water is the lifeblood of our planet. It is fundamental to the biochemistry of all living organisms. The planet’s ecosystems are linked and maintained by water. It drives plant growth and provides a permanent habitat for many species, including some 8500 species of fish, and a breeding ground or temporary home for others, such as most of the world’s 4200 species of amphibians and reptiles described so far. Water is also a universal solvent and provides the major pathway for the flow of sediment, nutrients and pollutants. Through erosion, transportation and deposition by rivers, glaciers and ice-sheets, water shapes the landscape and through evaporation and condensation, it drives the energy exchange between land and the atmosphere, thus controlling the Earth’s climate.