NASC 1001 week 7 Essay Discussion
Ocean Conveyor Belt and its Role
The great ocean conveyor belt of currents is responsible for the transfer of heat throughout the Earth’s oceans. This ocean water phenomenon is a result of the temperature difference in the ocean waters between the warm, salty surface water, and the less salty cold water in the ocean depths.NASC 1001 week 7 Essay Discussion
The surface cold water at the Polar Regions is saltier than deeper water due to both evaporation and the formation of sea ice, which squeezes out ice from the forming ice. This increases surface water density and causes it to sink to the ocean depths.NASC 1001 week 7 Essay Discussion
The pumping effect causes the cold water at the ocean depth to flow horizontally towards the tropics where it can displace lighter and warmer water to complete the current loop.
This motion of oceanic water is evident in equatorial waters, namely the Indian and Pacific oceans, due to variations in both water temperature and salinity; hence, the name thermohaline circulation.
One of the vital benefits of the great ocean conveyor is its ability to deliver life sustaining oxygen to the ocean depths. Oxygen gets mixed with the ocean water through the turning action of waves, currents and tides on the surface.
This motion is also responsible for the delivery of a warm climate that prevents the formation of sea ice in various parts of the northern hemisphere where the conveyor passes, such as Iceland and the southern region of Greenland.
It also provides the British Isles and Scandinavia with warmer temperatures than other landmasses at similar latitudes.
The region of the Southern Hemisphere where the ocean conveyor passes has no landmass, which allows the water to flow all around the world, resulting in the Antarctic Circumpolar Current. Consequently, the surface and deep waters flow eastwards around Antarctica, forming a link between waters from multiple oceans.
This causes the cold waters from the Indian and Pacific oceans to force themselves below the Atlantic waters, where the latter can join the surface circulation in its Northward flow.
The warm water forms part of the wind driven surface currents that return to the northern hemisphere where the cycle begins again in the region around Greenland.
The ocean conveyor is a product of two factors, salinity and temperature. As such, reducing salinity of the North Atlantic surface water may reduce the pumping effect to supplement the flow of cold deep ocean currents, causing the ocean conveyor belt to slow down or cease.
This phenomenon is said to have occurred in the period between 1400 and 1800 AD. This period is known as the Little Ice Age, when the Northern Europe’s climate was observed to be significantly colder than usual.NASC 1001 week 7 Essay Discussion
Scientists suggest that an increase in temperatures due the greenhouse effect is likely to result in melting of the polar ice, creating the dilemma of the possible implications with regard to the conveyor belt currents.
The ocean is not a still body of water. There is constant motion in the ocean in the form of a global ocean conveyor belt. This motion is caused by a combination of thermohaline currents (thermo = temperature; haline = salinity) in the deep ocean and wind-driven currents on the surface. Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and remains on the surface.
The ocean conveyor gets its “start” in the Norwegian Sea, where warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes. This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean. As more warm water is transported north, the cooler water sinks and moves south to make room for the incoming warm water. This cold bottom water flows south of the equator all the way down to Antarctica. Eventually, the cold bottom waters returns to the surface through mixing and wind-driven up welling, continuing the conveyor belt that encircles the globe.
The oceans are in constant motion both from winds that generate waves and currents and from the pull of gravity that creates the tides. A factor not as well known, thermohaline circulation, occurs deep within the ocean and acts like a conveyor belt as oceans absorb, store, and redistribute vast amounts of the Sun’s heat around the globe. Without this, places at the same latitude across the globe would generally have the same average temperatures. However, because of this circulation, Norway—located at similar latitude to Manitoba, Canada—has an average annual temperature that is nearly 20°F warmer.NASC 1001 week 7 Essay Discussion
Thermohaline circulation is driven by changes in the density of sea water. The conveyor belt transfers warm water from the Pacific Ocean to the Atlantic as a shallow current and returns cold water from the Atlantic to the Pacific as a deep current that flows further south. Beginning in the central Pacific, it travels past the north coast of Australia and around the southern tip of Africa before moving up into the Atlantic. By the time it heads up the Atlantic it turns into the Gulf Stream. As it passes Europe, the surface water evaporates and the ocean water cools, releasing heat to the atmosphere. This release of heat is largely responsible for the relatively warm temperatures enjoyed by Western Europe. As the water becomes colder, it increases in salinity and becomes dense, sinking thousands of meters below the surface. The deep water slowly travels south through the oceanic abyss, eventually mixing upward to the surface in different parts of the world up to 1,000 years later.
The ocean conveyor belt plays a crucial role in helping to shape the Earth’s climate. However, global climate changes could alter, or even halt, the current as we know it today. As the Earth heats up, there could be an increase in precipitation and a melting of freshwater ice in the Arctic Ocean (when salt water freezes it leaves the salt behind), which would flow into the Atlantic Ocean. This additional freshwater could dilute the Atlantic Gulf Stream to the point where it would not continue to sink into the depths of the ocean.NASC 1001 week 7 Essay Discussion