Why Are The Oceans Important

Why are the oceans important? The oceans have inspired human beings for thousands of years. From the earliest Polynesian canoes exploring and colonising the many hundred islands of the south pacific, to Greek mythology and later still to modern scientific method. However, it is with good reason that the oceans have played such a key role in the development of the human race. It has been our lifeline, and we are not the only specieswho are reliant on this vital resource to the planet. It could be argued that without these large bodies of water, our current atmosphere, and entire climate could not exist, and so life as we know it could never have evolved into the complexity that it is. It is also one of the major factors that can affect global warming. The oceans have an enormous holding over the weather patterns of the world. The specific heat capacity of water is the one of the highest of naturally occurring liquids, and is abundant on our earth’s surface. It takes 1000 times more energy to heat 1 cubic metre by 1°C of water than air. As the oceans cover around 70% of the earth surface, this plays a key part in the temperatures of the earth, and so the weather systems. Most of the changes in the earth’s temperatures are a result of heat being transferred between the atmosphere and the sea; not from heat escaping the atmosphere. Since the 1960’s, the ocean has absorbed 90% of the total excess heat as a result of global warming and greenhouse gases. 7%has been absorbed by land and ice and the atmosphere has absorbed only 3%. One example of this occurring is with the Atlantic Multidecadal Oscillation (AMO). This is a result of the speeding up and slowing down of the deep ocean current in the North Atlantic Oceanknown as the Thermohaline Circulation. When this speeds up, more warm water from the tropics is pushed up into the north Atlantic, and so transferring huge amounts of heat to the atmosphere. This causes surface temperatures in Europe and eastern North America to rise, the positive phase of the AMO. When the deep ocean current of the Atlantic slows down, less warm tropical water is moved into the north Atlantic, and so less heat is transferred to the atmosphere. This lowers surface temperature of Europe and eastern North America; the negative phase of the AMO. We are currently in the positive phase of the AMO, which may be contributing to the rapid melting of the arctic ice caps. If this is true, then the oceans could be partially to blame for accelerating global warming, as there is less sea ice to reflect the heat of the sun during the summer months. However, when the AMO enters the negative phase, then it could possibly give us more time to try and slow down our impact, or even help the climate. It must be noted that affects on the overall heat budget of the earth are not entirely

clear yet, so this is a grey area for how it will affect global warming. Even so, it looks as if the AMO is one of the key natural players that can make or break the dramatic rise in temperature.

Decade long fluctuations of monsoons in India may also have a relation to the AMO, as do the droughts in an area of Africa called the Sahel. In the short term, it could be highly beneficial to try and predict what and when the AMO will do;as it would give the areas affected some form of warning. El Niño is an anomaly of the South Pacific Ocean that also has as much, if not more, bearing on much of the earth’s weather. Normally, strong easterly trade winds push warm water across the pacific away from South America, where it wells up in the western pacific around South Asia. In turn, this causes nutrient rich cold water to well up all along the coast of Peru, so providing for a rich and diverse ecosystem. However, unknown to researches as yet, the atmospheric pressure gradients break down, and so the easterly trade windsweaken, or sometimes even reverse. Warm water is then allowed to spread across the surface of the Pacific Ocean in a thin layer. However this layer boosts the surface area of warm water in the Pacific, so increasing the amount of heat and moisture that is transferred to the atmosphere, changing circulation patterns. A strong El Niño caused 1998 to be one of the warmest years on record globally. Record rainfall in Ecuador and southern Peru, severe droughts in Australia, southern India, Indonesia and southern Africa have all been linked to strong El Niño effects. Also with El Niño, the warm nutrient poor water that is brought to the coasts of Peru and the Eastern Pacific causes catastrophic effects to the local ecosystems. Anchovy fisheries collapse along the coast, as do many coral reefs along the coast. Coral is at the base of many coastal communities, and if temperatures become too warm, the symbiotic plankton residing in the polyps are expelled. These are the main providers for the coral polyps, and so may corals will die without them, for they will not be getting enough nutrients and energy. One of the key producers of the ecosystem is then removed. Again, if there is anyway of predicting the patterns of the South Pacific Ocean, then it would be highly beneficial to those who are most affected. Measuring the ocean and predicting what it will do in the future wouldthen allow scientists to predict the weather and how it will behave in the next decade or 2. At the moment, El Niño can only be predicted around a year in advance, with it and its effects lasting between 3 to 8 years. However, despite El Niño dumping large amounts of heat energy into the atmosphere, it may

be that el Niño is in fact slowing global warming. It increases that amount of heat that is radiated into space, so lowering the total amount of heat within the Earth’satmosphere. Another key process that regulates the Earth’satmosphere is the ability for the oceans to dissolve carbon dioxide. This is due to the fact that Carbon dioxide reacts readily with water, forming carbonic acid. This can then dissociate into a bicarbonate ion and a hydrogen ion. Furthermore this can dissociate into a carbonate ion and a hydrogen ion. The atmosphere and all these stages of the reaction with the water are within equilibrium. If one is changed too much, the others will shift to counteract the change in equilibrium. There for if there is a significant increase in atmospheric CO2, then the oceans will in turn soak this excess up. This is good news for the atmosphere as it is removing much of the CO2that would normally act as a green house gas, and promote global warming. It is one of the key processes that maintain the atmosphere that we are used to. However, with the addition of so many hydrogen ions to the ocean, the pH is slowly dropping, becoming more acidic. This can be detrimental to many marine organisms. Again, coral are greatly affected by any change in pH. It is thought that as the pH drops, the coral becomes stressed and so expels the zooxanthellae that provide much of their energy. It is these creatures that provide the coral with its colour, and so with out they appear white, that is the calcium carbonate skeleton – coral bleaching. Without the help of these symbiotic creatures, the coral will soon die. As their skeletons are made of calcium carbonate, this reacts vigorously with acids, so also weakening the skeletons. So again the oceans provide a brief respite from our terrestrial problems, but are then only providing problems for other species. So as demonstrated, the oceans provide this planet with a great weather machine that at times seems random and both creative and destructive, it is also what provides the chaos that breeds evolution. It is indeed every species’ lifeline, which it can choose to cut at anytime. Such is its power that is its slightest change can be deemed catastrophic. However, it should be treated with respect, rather than to cause concern. We have indeed made it even more unpredictable, but the earth and its ocean can recover. It may just take may lifetimes, and many species with it to do.

References: New scientist 13th august 2008 Pg.26-30 Marine Biology with an Ecological approach; James W. Nybakken, Mark D. Bertness