Oceans+and+Coast+-Climate

= Explain the thermal transfers of energy within oceans and the importance of oceanic conveyor belts. = The ocean can hold and circulate more water, heat and carbon dioxide than the atmosphere although the components of the Earth's climate are constantly exchanged. Because the ocean can store so much heat, seasons occur later than they would and air above the ocean is warmed. Heat energy stored in the ocean in one season will affect the climate almost an entire season later. The ocean and the atmosphere work together to form complex weather phenomena like the North Atlantic Oscillation and El Niño. The many chemical cycles occurring between the ocean and the atmosphere also influence the climate by controlling the amount of radiation released into ecosystems and our environment.

The atmosphere directly above the ocean does not absorb much heat by itself, so in order for it to warm up, the temperature of the ocean has to rise first. The two other ways for the atmosphere to warm near the ocean are by reflection of light off of the surface of the ocean or by the evaporation of water from the ocean surface. The temperature of the ocean controls the climate in the lower part of the atmosphere, so for most areas of the Earth the ocean temperature is responsible for the air temperature.

=Oceanic Conveyor Belt= The main forms of climate buffering by the ocean are by the transport of heat through ocean currents traveling across huge basins. Areas like the tropics end up being cooled and higher latitudes are warmed by this effect. Air temperatures worldwide are regulated by the circulation of heat by the oceans. The ocean stores heat in the upper two meters of the photic zone. This is possible because seawater has a very high density and specific heat and can store vast quantities of energy in the form of heat. The ocean can then buffer changes in temperature by storing heat and releasing heat.

Evaporation cools ocean water which cools the atmosphere. It is most noticeable near the equator and the effect decreases closer to the poles. Thermohaline circulation moves a massive current of water around the globe, from northern oceans to southern oceans, and back again. The term thermohaline combines the words thermo (heat) and haline (salt), both factors that influence the density of seawater. The ocean is constantly shifting and moving in reaction to changes in water density. Water always flows down toward the lowest point. Waters density is determined by the waters temperature and salinity (amount of salt). Cold water is denser than warm water. Water with high salinity is denser than water with low salinity. Ocean water always moves toward an equilibrium, or balance.

For example, if surface water cools and becomes denser, it will sink. The warmer water below will rise to balance out the missing surface water Description The conveyor belt system can be thought of as beginning near Greenland and Iceland in the North Atlantic where dry, cold winds blowing from northern Canada chill surface waters. The combined chilling of surface waters, evaporation, and sea-ice formation produces cold, salty North Atlantic Deep Water (NADW). The newly formed NADW sinks and flows southward along the continental slope of North and South America toward Antarctica where the water mass then flows eastward around the Antarctic continent (in the Antarctic Circumpolar Current). There the NADW mixes with Antarctic waters (i.e., AABW and AADW). The resulting Common Water, also called Antarctic Circumpolar water, flows northward at depth into the three ocean basins (primarily the Pacific and Indian Oceans).

These bottom waters gradually warm and mix with overlying waters as they flow northward. They move to the surface at a rate of only a few meters per year. After rising to the surface in the Pacific, the surface waters flow through the many passages between the Indonesian islands into the Indian Ocean. Eventually they flow into the Agulhas Current, the Indian Ocean boundary current that flows around southern Africa. After entering the Atlantic Ocean, the surface waters join the wind-driven currents in the Atlantic, becoming saltier by evaporation under the intense tropical sun. Trade winds transport some of this water vapor out of the Atlantic Ocean basin, across the Isthmus of Panama, and into the Pacific Ocean basin. Atlantic surface waters eventually return northward to the Labrador and Greenland seas in the North Atlantic. []

Importance The great ocean conveyor is the circulation system of the ocean. The conveyor transports both energy and matter around the world in an identifiable circulatory pattern. This system is conceptualised as acting like a giant conveyor belt taking heat energy across immense ocean distances in the air-driven currents of the oceans as well as any material substances that happen to have found their way in there. The conveyor is of great importance to the climate and may be linked to carbon dioxide levels in the air. Besides the heat energy that is being transported, the great ocean conveyor is also transporting matter around the oceans as well. This can include a variety of different substances from solids to gases to dissolved substances. Anything that finds its way into the ocean could potentially find itself going on a very long journey as the circulatory system takes hold of it. The great ocean conveyor plays a highly significant part in the climate of the planet. It transports heat to the Polar Regions, for example. In doing so, the amount of ice that can be formed in these regions is limited. It has also been suggested that the thermohaline circulation is a significant factor in determining the carbon dioxide levels that are found in the air.

The great ocean conveyor is one of the major forces that shape our world's climate and any changes to it could have major consequences for all life on earth. Continued operation of the oceanic conveyor belt is important to northern Europe's moderate climate because of northward transport of heat in the Gulf Stream and North Atlantic Current.

The system can weaken or shut down entirely if the North Atlantic surface-water salinity somehow drops too low to allow the formation of deep-ocean water masses. This apparently happened during the Little Ice Age (about 1400 to 1850 AD). The conveyer system shut down and northern Europe's climate became markedly colder. Old paintings from this era show Dutch skaters on frozen canals-something that would not occur during today's climatic regime. Cores extracted from deep-sea sediment deposits contain evidence of earlier cold periods. []

= Examine the role of oceans as a store and source of carbon dioxide (CO2). = The oceans influence the climate by absorbing and storing carbon dioxide. Climate change is caused by the accumulation of man-made carbon dioxide (CO2) and other greenhouse gases in the atmosphere. The rate of accumulation depends on how much CO2 mankind emits and how much of this excess CO2 is absorbed by plants and soil or is transported down into the ocean depths by plankton (microscopic plants and animals). Scientists believe that the oceans currently absorb 30-50% of the CO2 produced by the burning of fossil fuel. If they did not soak up any CO2, atmospheric CO2 levels would be much higher than the current level of 355 parts per million by volume (ppmv) - probably around 500-600 ppmv. Plankton influence the exchange of gases between the atmosphere and the sea. In any given region, the relative amounts of CO2 contained in the atmosphere and dissolved in the ocean's surface layer determine whether the ocean-water emits or absorbs gas. The amount of gas dissolved in the water is in turn influenced by the amount of phytoplankton (microscopic plants, particularly algae), which consume CO2 during photosynthesis. Phytoplankton activity occurs mostly within the first 50 metres of the surface and, although oceanographers don't fully understand why, varies widely according to the season and location. Some areas of the ocean do not receive enough light or are too cold. Other areas appear to lack the nutrients or trace minerals required for life, or zooplankton (microscopic animals) that feed on phytoplankton so limit the population growth of the latter that not all of the available nutrients are consumed.

Rather like a pump, plankton transport gases and nutrients from the ocean surface to the deep. Their role in the carbon cycle is quite different from that of trees and other land plants, which actually absorb CO2 and serve as a storehouse, or "sink", of carbon. Instead, ocean life absorbs CO2 during photosynthesis and, while most of the gas escapes within about a year, some of it is transported down into the deep ocean via dead plants, body parts, faeces, and other sinking materials. The CO2 is then released into the water as the materials decay, and most of it becomes absorbed in the sea-water by combining chemically with water molecules (H2O). Although a small but possibly significant percentage of the sinking organic material becomes buried in the ocean sediment, most of the dissolved carbon dioxide is eventually returned to the surface via ocean currents - but this can take centuries or millennia. Measuring the level of plankton activity in the ocean is difficult. The rate at which plankton consume carbon dioxide and convert it into sugars for producing tissue and energy varies enormously. This makes it difficult to sample and estimate their annual consumption of CO2. The enormous expanse and remoteness of the oceans (few oceanographers want to go to Antarctica in the middle of winter) also hampers sampling. Satellite pictures of chlorophyll (cell pigment that converts sunlight into energy) give a general idea of the amount of phytoplankton present, and oceanographers hope that future satellite measurements will further clarify the picture.

Climate change will affect plankton, and vice versa. Warmer temperatures may benefit some species and hurt others. Changes in carbon dioxide levels may not have a direct impact, but related "feedback loops" could be important. For example, because plankton create a chemical substance called dimethylsulfide (DMS) that may promote the formation of clouds over the oceans, changes in plankton populations could lead to changes in cloudiness. At the same time, more clouds would reduce the amount of solar radiation reaching the oceans, which could reduce plankton activity. Another possible feedback could occur near the poles. If global warming causes sea ice to melt, more light would reach and warm the surface waters, either benefiting or damaging certain plankton. (The depletion of the ozone layer by CFCs also increases the amount of ultra-violet light reaching the surface, which could have negative effects on the plankton.)

Most scientists are sceptical about proposals to artificially increase CO2 absorption by "fertilising" key ocean regions. For example, because Antarctic phytoplankton are surprisingly sparse considering the quantity of available nutrients, a few scientists have theorised that fertilising the Southern Ocean with iron would boost populations and thus the amount of CO2 absorbed from the atmosphere. Insufficient iron, however, is only one of many possible reasons for low biological activity in the Southern Ocean, and too much iron could poison some plankton. Computer models also indicate that an increase in plankton off Antarctica may not actually lower atmospheric carbon dioxide levels significantly over the next 100 years. But the real danger, of course, is that manipulating biological systems that are not thoroughly understood could have negative consequences just as easily as positive ones.

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