Earth is known as the blue planet because three-quarters of its surface are covered by water, enough to inundate the US to an astonishing depth of 150 kilometres. However, this impression of abundance is illusory. Only 2.6 percent of the total is fresh water, and of that almost all is either locked up in glaciers and ice-sheets (76.6 percent) or held as groundwater in aquifers, layers of rock or soil capable of holding large quantities of water (22.9 percent). Fresh water available for human consumption amounts to only 0.01 percent of the total water on the planet.
Sustainable Development: Thirsty World
Holes in the ozone layer get bigger and the earth gets warmer. Sea levels are rising significantly. And yet potentially the most serious physical problem facing the twenty-first century lies elsewhere – the supply of good quality fresh water – a major item on the World Summit on Sustainable Development’s agenda in Johannesburg.