Availability of water

We call it the blue planet: water covers 70% of the surface of the Earth, which is an enormous amount of water! Well then, why all the fuss? Is water really running out all over the world?


Well, it's not really running out. The land, the oceans and the planet's atmosphere contain a fixed amount of water -about 1,260 million trillion gallons- in the form of ice, vapor or liquid. And nature makes this water circulate non stop through the process known as the hydrologic cycle (see below). This means that the water from your tap is as recycled as the air you breathe.Thousands of years ago it could have been used by a dinosaur!


The real problem is availability. About 97% of the water on Earth is in the oceans, and therefore it not suitable for drinking. 3% of freshwater is mostly ice, groundwater and others, leaving only about 0.3% in the form of lakes, rivers, reservoirs and underground sources that are replenished by the processes of evaporation and precipitation, ready to be used by humans.


This relatively small amount is distributed very unevenly around the world: in deserts, for example, it hardly ever rains, but in tropical forests several meters of rain fall every year. Most of the drinkable water is carried by some of the largest rivers in the world: the Amazon and the Congo, while the arid and semiarid regions (that comprise 40% of the continents on Earth) only hold 2% of the water.


In regions where water is abundant, it is often wasted: it is polluted, wasted and overexploited. The population keeps growing all over the world, consumerism increases every day: we are overdoing the use of this finite resource.


Copyright © 2012 Water, the New Petrol Team
CEP Santa Rosa Marist Brothers - Sullana (Peru) and IES Manacor - Mallorca (Spain)
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