Wikibooks: High School Earth Science/Problems with Water Distribution

• Format: Book
• Language: English
• Subjects: Antarc*; Antarctica; Greenland
• Online Access: https://en.wikibooks.org/wiki/High_School_Earth_Science/Problems_with_Water_Distribution

TOC right Humans are facing a worldwide water crisis according to the United Nations. The crisis includes worldwide shortages of fresh water that humans can access scarcity of safe drinking water supplies and water pollution. =Learning Objectives= Explain why water shortages are increasingly frequent throughout the world. Discuss why 1.1 billion people (one fifth of the people on Earth) do not have access to safe drinking water. Explain why humans can use less than one percent of all water on Earth. Discuss the ways in which human water demands are unsustainable. =World Water Supply and Distribution= Water is everywhere. More than 70% of the Earth s surface is covered by water. The Earth has a limited supply of water that we can use. There are supplies of freshwater in lakes rivers streams swamps reservoirs and even underground water rich regions of soil and rock called aquifers . 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 it is frozen in glaciers and icebergs mainly in Greenland and Antarctica (Figure 21.10). 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. Global warming affects patterns of rainfall and water distribution. As the Earth warms regions that ...