The freshwater crisis: Basic elements

Abstract

The entire stock water on the “blue planet”, Earth, is estimated at approx. 1.4 billion km³ (Fig. D 1.1.-1).The world’s oceans, which over 71% of the Earth’s surface, account for 96.5% of that total.The rest is found as polar ice masses and glaciers (1.77%), as groundwater (1.7%) and as the water of lakes, swamps, rivers permafrost and the atmosphere (0.03% all told).Freshwater stocks account for only 2.5% of the total volume of water in the hydrosphere (35.1 million km³),of which 69% is stored in glaciers and permanent snow cover and around 30% as groundwater.A mere 0.3% of all surface water is freshwater.Although the water volume on the planet has been constant for a long time, distribution among the three different water phases (ice, water and water vapor)has been subject to major fluctuations during Earth’s history.