Water (Episode 3)
Water makes the earth unique. All life depends on it and humans utilise it in many ways. Yet they contaminate it too, transforming entire landscapes and thereby intervening in important cycles.
The ability of water to assume three aggregate states is a guarantee for the water cycle that makes life on earth possible. This enables fresh water to be available at all times. But enrichment with CO2 turns rain into acid rain, which causes problems for forests and seas.