Earth's water cycle

Imagine the world without water: as cold and lifeless as the planet Mars. Earth is unique in our solar system in being able to sustain liquid water on its surface. Water is essential for life and for Earth’s climate, helping transport heat around the planet, but it is difficult to track through the whole water cycle. The global view offered by satellites helps. ESA’s Climate Change Initiative is looking at a range of climate variables linked to the water cycle.