Global Warming May Impact The Functioning Of The Deep Ocean Thermohaline Circulation

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Critically evaluate the extent to which global warming may impact the functioning of the deep ocean thermohaline circulation.
What is the Thermohaline circulation?
The Circulation of the world’s oceans can be divided into the upper and the lower. The upper few 100 metres movement is generally wind-driven whereas below this, circulation is driven by the heating and cooling of waters producing regional density differences. This creates the ‘Thermohaline circulation’ (THC), otherwise known as the Great ocean conveyer, an overturning circulation system.
Waters move extremely slowly, 10cm/s at its fastest however, it moves a very large amount of water and information from radiocarbon dating shows that the whole of the ocean deep waters are over turned around every 600 years. The density is controlled by the temperature of the water (thermo) and the salt content (haline). Water gets colder during heat loss to the atmosphere, especially at high latitudes, and consequently becomes denser. Conversely, water gets warmer when it is heated by arriving solar energy, specifically at low latitudes, and consequently becomes less dense. Water becomes saltier if evaporation rates are high as evaporation favours pure water molecules (as they are less dense) leaving behind saline and thus more dense waters. This leads to sinking of waters at high latitudes and upwelling of waters at lower latitudes, both of which are fed by horizontal currents (Gordon, 1986). However, water becomes less saline
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