Oceans have different types of water movement. Tide is one, which is known to everybody who has seen an ocean. Tides are regular movements of the waters caused by the pull of the moon and the sun. There is another movement of ocean water, which is called ocean currents.
These are like rivers of water flowing through the ocean and cause circulation of ocean waters. These are warmer or colder than the waters through which they pass. Patterns of circulation in the oceans are determined by major patterns of atmospheric circulation and are modified by the large landmasses around and against which they must flow.
Ocean currents have direct effect on the temperature of adjacent land areas. For example, there is a pole ward movement of warm ocean currents, such as the North Atlantic Drift. This keeps winter temperatures in Britain and other parts of Western Europe warmer than they should be according to their geographical positions. Westerly winds in these areas carry the heat towards land.
In the tropics and middle latitudes, there are cold ocean currents during the summer. One such current is Benguela current, which flows in the ocean near the western coast of Southern Africa. This current helps in reducing the temperature in the tropical region. So, the ocean currents have their own impact on climates of different part of the world. You may have heard of ‘EI Nino’. It is also an ocean current of the Eastern Pacific. It is supposed to have played an important role in causing extreme weathers during 1982-83. When the climate is affected by such currents, the flora and fauna will also be affected, which ultimately affects the whole ecosystem.