rivers, streams, swamps, reservoirs, and even underground water rich regions of soil and
rock, calledaquifers. Almost anywhere you stand, there is water somewhere beneath you.
Sometimes that water is just several meters below you, sometimes it is deeper within the
Earth.
Still, this supply of freshwater is less than 1% of all of the water on Earth. Why is so little
water available for human use? Two reasons:
- For most of our needs, humans cannot use saltwater, which makes up 97-98% of all
water on Earth. - Humans cannot use most of the freshwater on Earth, because is frozen in glaciers and
icebergs, mainly in Greenland and Antarctica (Figure21.10).
Figure 21.10: Most fresh water on Earth is in the form of frozen icebergs and glaciers. ( 11 )A common misconception is that water shortages can be solved by desalination, removing
salt from seawater. This is because the desalination process requires so much energy and is
so costly, that it is not an economical way to increase freshwater resources.
Water Distribution
Look closely at the climates of different regions around the Earth. Some places have water
rich climates, while many others do not. Roughly 40% of the land on Earth is arid or
semiarid, which means it receives little or almost no rainfall.
Water Distribution: Water is unevenly distributed across the world. The blue areas are the
most water rich regions of the world. The salmon pink areas are desert areas. (Source:http:
//earthtrends.wri.org/maps_spatial/maps_detail_static.php?map_select=264&
theme=2.CC-BY-SA)