Importance of Water for Global Processes

In addition to its critical role for human consumption, water also is a key element in many natural functions of the planet. For instance, a map of global vegetation patterns correlates very strongly with global land precipitation patterns: rainfall is a strong regulator of vegetation. As we have seen in the unit on Ocean Structure and Circulation, fresh water has a lower density than salt water of the same temperature. Fresh water from precipitation or snow/ice melt may ride on top of more salty water and thereby influence the vertical mixing in oceans and also global ocean circulation patterns.

Water in the form of hydropower also is a source of renewable energy as a byproduct of evaporation of sea and lake water and subsequent precipitation at high altitudes producing stream and river flow. Another critical aspect of water is its role as a medium for ecosystem functioning. Many chemical, physical, and biological processes take place in water bodies or in the presence of water in soil. These provide critical transformations that allow diversity of ecological systems.

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