The Ocean conveyor belt or more accurately, the thermohaline circulation refers to the continuous cycle of water in the ocean due to its temperature and salinity. The working principle behind it is that water from different parts of the ocean has differing densities, whereby colder saltier water is denser than warmer less salty sea water. (expansion of liquids) Water which is less dense tends to float while denser water tends to sink, resulting in the movement of water in the oceans to achieve this balance.
How did this different density occur in the first place?
In the North Atlantic, winds blowing over the ocean remove latent heat of vapourisation as the water evaporates, becoming cooler. Less water in the ocean coupled with the same amount of salt causes the water to become denser. In addition, when ice is formed on the ocean in those regions, pure water tends to freeze rather than salt water. Again, less water in the ocean to dissolve the salt would cause the concentration to increase even further. This denser ocean water forms the North Atlantic Deep water (NADW) which flows southwards through deep abyssal plains found along the Atlantic.
Down to the Antarctic this denser ocean water then flows along the Antarctic continent mixing with the Antarctic bottom water to give 'common water' where it splits up to the Indian Ocean and Pacific Ocean. Following this route.
The Pacific Ocean having a slightly higher water level than the Atlantic Ocean would flow its upper most water through Indonesia to replace the water from the Atlantic that had travelled along Antarctica. Thereafter it travels North back to Greenland where it all began, starting the cycle all over again.
Ps: Any readers please enlighten me on the terms 'over turning' and 'Haline forcing' I did not use it in my text in fear of being inaccurate! Picture from politicalclimatewordpress.com
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