Trends and global prospects of the Earth’s aquatic ecosystems

The Earth's organisms have depended on water since they arose 3.5 billion years ago. In the last 10000 years, human development of stone tools, learning of food cultivation, growth of civilizations and trade, and migration among others have increasingly impinged on aquatic ecosystems. During the last century, the human population has tripled, and water use for human purposes increased six-fold. Approximately half of all available fresh water is now used to meet human ends, twice what it was 40 years ago (World Water Council [WWC] 2000), and by 2025, the withdrawal of water is projected globally to increase by at least 50% (Martinez Austria & van Hofwegen 2006)