Water: A Continually Renewable Resource
Water is absolutely fundamental to life as we know it. It is difficult even to imagine a form of life that might exixt without water. Happily, Earth is virtually flooded with water.
★ A total volume of some 325 million cubic miles ( 1.4 billion cubic kilometers ) covers 71% of Earth's surface.
★ About 97% of this volume is the salt water of oceans and seas.
★ The remaining 2.5% of this volume is Fresh Water with salt content less than 0.1%
( 1,000 ppm ).
★ This is the water upon which most terrestrial biota, ecosystems , and humans depend.
★ Of 2.5%, though two-thirds is bound up in the polar ice caps and glaciers.
★ Thus only 0.77% of all water is found in lakes, wetland, rivers, ground water, biota, soil, and the atmosphere.
★ Nevertheless, evaporation from the oceans combines with precipitation to resupply that small percentage continually through the solar-powered hydrologic cycle as FRESH WATER is a continually renewable resource.
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