4. Oceans & Atmosphere

Oceans cover more than 70% of the Earth's surface and make up 97% of its surface water. It's no surprise they have a big influence on the planet. They affect the atmosphere, climate and living things.

Oceans are a major source of water vapor in the atmosphere. Sunlight heats water near the surface. As the water warms, some of it evaporates. The water vapor rises into the air. It may form clouds and precipitation. Precipiation provides fresh water needed by plants and other living things. 

Ocean water absorbes gases from the air too. It absorbs oxygen and carbon dioxide. Oxygen is needed by living things in the oceans. Much of the dissovled carbon dioxide sinks to the bottom of the water. Carbon dioxide is a major greenhouse gas; by absorbing carbon dioxide, the oceans help control global warming. 

The oceans and atmosphere exchange gases like carbon dioxide, oxygen and water vapor. Image courtesy of USOE. 

Compared with inland areas, coastal areas have a milder climate. They are warmer in the winter and cooler in the summer. That’s because land near an ocean is influenced by the temperature of the water. The temperature of ocean water is moderate and stable. Why?
There are two major reasons:

  • Ocean water is much slower to warm up and cool down than land. As a result, it never gets as hot or cold as land.
  • Water flows through all the world’s oceans. Therefore, warm water from the equator mixes with cold water from the poles. The warm and cold water tend to “cancel each other out.”

Even inland temperatures are milder because of oceans. Without oceans, there would be much bigger temperature swings all over Earth and life would not be able to exist as it does now.


Source: USOE OER Resources. Retrieved from http://www.slcschools.org/departments/curriculum/science/documents/4-Earth-Science.pdf on September 1, 2013. 

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