Oceans & Climate

The ocean currents and impact on climate is ultimately driven by the sun. Photo courtesy of Royal19/Flickr.

Whether you live on the gentle rolling plains of the Midwest or the glittering desert sands of the Southwest – no matter where in the world you are – your life is intimately tied to our planet's oceans. Even if you've never gone to a beach to watch a sunrise or sunset or to ride the waves, the oceans probably affected you as recently as this morning – when you may have checked the weather and decided what to wear.

The oceans influence the world's climate by storing vast amounts of solar energy and distributing that energy around the planet through currents and accompanying atmospheric winds. Dramatic weather events like hurricanes originate at sea, and the oceans also influence long-term conditions such as average daily temperature and rainfall. These factors in turn affect the variety and volume of crops that can be grown and the number of fish that can be caught. In fact, the oceans affect all life on our planet.

In the complex recipe of Earth's climate and weather, no ingredient is more important than the Sun. Without its intense energy, life on our planet would be impossible. At an average distance of 93 million miles (150 million kilometers), only 1/2 billionth of the Sun's energy reaches Earth. Yet even that fraction of the Sun's power is massive—totaling some 1.8 × 1014 kilowatts, or more than 300,000 times the electrical generating capacity of the United States!

Not all of that solar radiation reaches the surface of Earth. Some energy is scattered by the atmosphere on its way to the surface or is reflected back by the clouds, leaving about 45 percent to complete the journey. This solar radiation is absorbed (as heat) in differing amounts by the various surfaces on Earth. Land areas heat up quickly during the day and cool rapidly at night, radiating much of their energy back to space. Luckily, atmospheric gases such as carbon dioxide and water vapor retain certain types of radiation that warm the atmosphere. Scientists have termed this phenomenon the greenhouse effect.

As compared with the continents, the world's oceans absorb much more of the incoming solar radiation and reflect much less back to space. That is because water has a higher heat capacity (holds more heat per unit volume) than land or air. Not surprisingly, the oceans' higher heat capacity directly affects the climate of our planet. The insulating effect of water gives coastal areas a more moderate range of temperatures than inland areas have at the same latitude.

The energy from the Sun (in the form of heat) fuels the circulation of Earth's atmosphere. Regions near the equator receive more heat than those near the poles. Warmer, lighter air rises at the equator while cooler, denser air sinks at the poles. This sets up a pole-to-equator movement of air at the surface and an equator-to-pole movement of air aloft, although actual atmospheric circulation is somewhat more complex. Because of Earth's rotation, atmospheric winds appear to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Source: MSP2. Oceans, Weather, and Climate. Retrieved from http://msteacher.org/epubs/science/science6/forecast.aspx on November 19, 2010.
Last modified: Tuesday, 8 March 2011, 11:10 AM