One of the major issues which are facing us today is that of climate change. Climate change is defined as a change in the either the regional or global pattern from the statistically calculated historical data. Since the beginning of the 20th century a change in climate not explained by normal historical variation has been observed. This change has mostly been determined to be the result of increased levels of carbon dioxide in the atmosphere, as a result of increased usage of fossil fuels (Karl and Trenberth). While climate change can have many negative impacts, one major negative impact is that of its effects on coral reefs, such as the Great Barrier Reef. Coral is an unmoving, or sessile animal. They are formed as the result of a symbiotic relationship between the coral, which is a polyp that has a limestone skeleton, and photosynthetic algae known as zooxanthellae. The coral provides the algae with a safe place to live; and the algae provide oxygen and remove waste products from the coral (Stimson et al.).
The Great Barrier Reef, located off the coast of Queensland Australia, is the largest coral reef system in the world. It is made up of over 2900 reefs and covers an area of over 344,400 square kilometers (Hopley et al.). However, as a result of several different events caused by climate change, this has altered and negatively impacted the Great Barrier Reef. These events include increased water level, ocean acidification, increased ocean temperature, and coral bleaching.
As global temperatures increase, this leads to an increase in the level of water around the Great Barrier Reef. This increase in water level can have a major impact on the reefs as most of the coast line is at a shallow depth. If the water level increases this can increase the turbidity of the water and can lead to a smothering of reefs, causing them to die off. As well typically corals do not grow at depths greater than 50 meters, as the level rises this could impact the areas in which it is able to grow. However, based on current estimates most scientists believe that out of all the other factors which will occur as a result of climate change, this factor is of the least concern (Hopley and Kinsey).
Ocean acidification is another risk factor, and according to some scientists is likely to be the factor which has the most impact on the Great Barrier Reef. The oceans absorb carbon dioxide, as the levels of carbon dioxide increase in the atmosphere; the ocean will absorb more of it forming carbonic acid. This carbonic acid then leads to the formation of a bicarbonate ion and a hydrogen ion. The hydrogen ion then binds with carbonate forming another bicarbonate molecule. This lowers the amount of carbonate available for making the calcium carbonate shells of coral. Therefore this can drastically reduce the amount of coral growth that occurs (Hoegh-Guldberg et al.).
Also of major concern is that of increasing temperatures. Corals survive within a very small temperature range. Usually corals grow in waters that are between 20°C to 32°C. Outside of this temperature range corals will begin to die. When the temperature of the water increases, the coral becomes stressed and forces the symbiotic algae to leave (Stimson et al.). When this occurs, the coral then loses its color and becomes completely white. After the coral has turned white it starts to starve; as a result some coral begin to feed on themselves. If the temperature returns back to normal within a short period of time, then the coral may be able to recover. However, as climate change is permanently altering the temperatures, the coral will most likely not recover and will remain bleached and eventually die (Lesser).
This phenomenon of coral turning white is known as coral bleaching. When two bleaching events, one in 1998 and one in 2002 where compared it was found that in the 2002 event which had a higher and more sustained increase in temperature, had more loss of coral than that of the 1998 event. This means that overtime as the temperature continues to warm, more coral will be lost to bleaching (Berkelmans et al.).
If climate change continues to occur it is likely that the entire Great Barrier Reef will disappear, as it will be unable to cope with the changing environment. However, there is still time to take measures to prevent this from occurring. One of the main solutions for saving the Reef is to reduce the amount of carbon emissions. When possible if people take public transit, walk or bike, this can help to reduce the amount of carbon that comes from using fossil fuel in our cars(Verweij et al.).
As well, more research is needed to determine exactly what is causing the death of coral. For example a recent study showed that it was the combination of acidification and increased temperature that leads to decreased survival after coral bleaching (Anlauf et al.). Therefore more research is needed to determine if there is a way to prevent the occurrence of these two conditions. By providing more funding, and also by funding efforts to reduce the amount climate change by investing in green energy solutions, this could save the coral. By working together it is possible to prevent the disappearance of coral not only in the Great Barrier Reef, but all across the world.
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