Oceans are vast water bodies that cover 70% of the Earth's surface. These massive water bodies have a great influence on the temperature of the earth’s atmosphere. Most scientists are of the opinion that ocean currents that flow thousands of kilometers moderate the air temperature and climate near the shores. Interestingly, the Gulf Stream warm water current has a huge impact on the north western countries of Europe. Countries like U.K. and Scotland would have been severe cold in absence of warm ocean currents.
The horizontal and vertical movements of water throughout the oceans around the world are called ocean currents. There are two types of ocean currents namely surface currents and deep ocean currents. The surface currents account for 10% of all the ocean currents. It is usually found within the upper 400 meters of the ocean. On the other hand, the deep ocean current is found below a depth of 400 meters. These ocean currents circulate worldwide. As a result they are capable of carrying energy and moisture and affect the air temperature. The Humboldt Ocean Current of the Pacific Ocean is responsible for the moderate air temperatures of Chile and Peru.
Ocean currents are the results of wind. As wind blows over the ocean, it causes surface water to drift in its direction. The moving water gets collected. Within the water a pressure gradient is created as a result of this accumulation. The pressure gradients give rise to ocean currents. Ocean currents transfer heat to the poles from the equator. When the water drifts away along with wind, cold water rises up from below to replace it. They are nutrient rich and transfer heat. This process is called "upwelling". The oceans are massive storehouses of carbon dioxide. The phytoplankton species can extract this greenhouse gas from the atmosphere. If the ocean temperature is warm then more of these plants are expected to grow in the oceans. These can utilize and reduce atmospheric carbon dioxide. This phenomenon is a negative feedback mechanism. Warm ocean temperatures on render the oceans incapable of dissolving excess of carbon dioxide. This is a positive feedback mechanism. So the greenhouse gas keeps accumulating in the atmosphere. As a result, the temperature increases in the onshore sites. The near shore or onshore temperature is largely affected by upwelling, continental air masses, river runoffs and higher cooling and heating rates. Among these factors upwelling is the most dominant factor. This explains the differences between near-shore and offshore air temperature. The near-shore air temperature is often much colder than offshore sites.
Toxic chemicals, manufacturing wastes, fertilizers, refuse disposal, oil spills, surface runoffs, plastic and radioactive wastes are constantly contaminating the oceans. Hazardous chemicals are being banned worldwide. But at the same time new chemicals are replacing them. And these wastes are getting dumped into the ocean. The ocean currents are very strong enough to carry these wastes. These toxic wastes affect the marine life of the oceans and air temperature adversely. Excessive carbon dioxide has also increased the acidity of the ocean. All these factors are impacting the capability of the ocean to absorb carbon dioxide. As a result of all these factors, ocean temperature is rising. And in a cyclic way, the air temperature is getting affected. In the recent times, UK’s leading scientific academy "The Royal Society" has submitted an appeal asking almost all world leaders to share the responsibility for controlling carbon and other greenhouse gas emissions.
If the ocean temperatures change so drastically, then the balance of our ecosystem is bound to get disturbed. Fossil fuels add greenhouse gases in the atmosphere. We should reduce our dependency on the fossil fuels by adopting renewable sources of energy. Every government should impose strict penalty to prevent litter in rivers, streams and oceans. Ocean pollution can also be prevented by banning the use of the toxic or harmful agricultural chemicals. Both state and local government should implement laws to stop industry dumping chemical wastes in the oceans and seas.
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