1. Source of moisture:
The oceans play a very important role in the hydrological cycle. The ocean is the main supplier of moisture through the process of evaporation. Moisture can be carried towards the land in the form of humid air or clouds. When moisture rises up the continents it cools and condensation occurs. Clouds and rain is formed. The water may return to the oceans either with direct run-off (in rivers) or indirect run-off (groundwater)
The world's oceans cover 71% of the earth's surface and 97% of all water.
2. Source of oxygen
The oceans are the main supplier of oxygen to the atmosphere. The oceans contain oxygen as an element of water (H2O). Many living organisms in the oceans have the ability to absorb CO2 and release O2 back into the atmosphere (photosynthesis). Think of all the coral and phytoplankton which are the producers in the ocean.
3. Source of protein food
The world's population according to the World Bank was 6,692,030,277 in 2008. The population is roughly growing at 1.17% per annum. Many people (1 billion) eat fish as a staple diet and source of proteine. The fishing industry world wide have increased dramaticaly. In 2009 the global seafood market exceeded 123 million tons.
4. Source of energy supply
The energy crises the world is currently experiencing has caused scientist to seacrh for alternative energy resources. The ocean covers 71% of the earth's surface, and therefore, most energy will be found in the oceans.
i) Wave power
Wave power is generated when electricity generators are placed in shallow waters or surface of the ocean. As the wave moves through the turbines energy is generated.
ii) Tidal power
Generators are placed in deep, narrow estuaries where the tidal effect is between 5-10m.
However, both methods are quite expensive and corrosion of machinery by salty sea water results in high maintenance costs. Stormy seas can also damage generators.
