Earth Science

Water on Earth

Distribution of Water on Earth

Study Tip
To help remember the function of reservoirs: Reservoirs reserve water.

Distribution of Water

  • Earth’s oceans contain 97% of the planet’s water
  • 3% of Earth’s water is fresh water, water with low concentrations of salt
  • Most fresh water is trapped as ice in glaciers and ice sheets of Greenland
Study Tip
To help remember the function of reservoirs:
Reservoirs reserve water.
  • Reservoir: storage location for water
  • Can be an ocean, glacier, pond, or the atmosphere
  • Water molecule may pass through a reservoir very quickly or remain for much longer
  • Residence time: amount of time a molecule stays in a reservoir
Distribution of Water
The distribution of Earth’s water
Concept Check
  • If Earth is the water planet, why is water sometimes a scarce resource?
  • What are the reservoirs for water?
  • In which reservoirs does water have the longest residence times? The shortest?