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Ocean and Climate -- The Odd Couple

Our global climate has changed drastically and frequently over our planet's lifetime. Some global climate fluctuations are on a human-time scale (check out our El Niño page). So what do the oceans have to do with climate? A lot! The oceans and the atmosphere form a closely linked "dynamic duo." Energy from the sun, plant distributions, and greenhouse gasses in the atmosphere can affect temperature and circulation patterns of this ocean-atmoshpere duo.

The sun is Earth's main source of energy. Solar energy is absorbed by both oceans and continents. BUT--because the oceans cover over 70% of Earth's surface and are darker than the continents--they absorb more of the sun's energy. Here's another BIG IDEA! Oceans not only absorb lots of energy from the sun--they can also store lots of solar energy in the form of heat. AND they can do this with very little change in temperature. Scientists believe the way the oceans store and transport heat is related to climate.

The Heat Budget, source Keihl & Trenberth, J. Amer. Meteorological Soc. 78(2): 197-208. Click on the Image for a larger view! The Heat Budget, source Keihl & Trenberth, J. Amer. Meteorological Soc. 78(2): 197-208. Click on the Image for a larger view!

The arrows that you see on this image portray the amounts of incoming and outgoing solar insolation and how the energy interacts with different parts of Earth and its atmosphere. As you can see from this schematic, roughly half of the incoming solar radiation is absorbed by the ocean. In turn this heat energy is stored in the water as it is picked up by winds which blow over the ocean surface. When the wind releases the water as precipitation the heat energy of the water is released into the atmosphere causing an increase in temperature.

The oceans' waters are constantly on the move. These movements are caused by powerful wind-driven currents (see our "Currents" page). Earth's rotation and continents plus "things" going on inside the ocean can create currents or movement of water.

Deep ocean currents, however, are created by density. Density is defined as mass per unit volume of a substance and is measured in grams per cubic centimeter, or g/cm3. More simply:

  • The density of seawater (ocean water) is greater than the density of pure water at the same temperature because seawater contains salts.
  • Cold seawater (ocean water) is more dense than warm seawater because the molecules of cold seawater are closer together than the molecules of warm seawater.
  • Less dense substances will float on more dense substances.
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