Over the past century, humans have burned an enormous amount of fossil fuels. By burning all these fossil fuels, it has increased the amount of carbon dioxide in our atmosphere. With all of this new carbon dioxide, it is causing our planet to warm. Recent temperatures had been the highest they have ever been and they continue to rise. Not only do we think the temperature outside is warmer, our oceans are heating up as well. Coral Reefs need zooxanthellae, when the water gets warmer the zooxanthellae leave the coral, and they are what provide oxygen for the coral. If sea temperature continues to heat up, there will be massive coral bleaching. The oceans absorb about 1/3 of all carbon dioxide from our atmosphere each year, helping reduce global warming. If there is too much carbon dioxide from fossil fuels, it will change the oceans chemistry by lowering the pH, which makes it more acidic, and rising the oceans temperature. If the water is too acidic, sea creatures and coral will not be able to make their calcium carbonate shells. In our oceans there is hundreds of thousands of marine life. Even just the slightest degree change and lead to disaster. Over the past century, scientists had seen a huge decrease in coral reefs. Coral reefs are very important in our environment, and contain thousands of marine life. However they are very fragile, sensitive and easily stressed by environmental changes. Once coral is stressed, their immune system is compromised and can easily contract a disease. If global warming continues, there will be no corals reefs left and many marine life will be extinct. Coral reefs provide shelter and food for marine life, but it is also a tourist attraction for humans and provides over 1 billion dollars of revenue per year.
Burning fossil fuels has released carbon dioxide that was stored for millions of years. In the last 200 years we have burned a large amount, resulting in an increase in carbon dioxide in our atmosphere (Baumert, Herzog, & Pershing, 2005). Before the industrial revolution, the atmosphere contained about 280 parts per million of carbon dioxide, and today it is 35% higher, greater than 380 ppm (Eakin, Hoegh-Guldberg, Kleypas, 2008). The ocean absorbs 25% to 33% of all the carbon dioxide added to the atmosphere each year (Wilkinson, 2008) and helps reduce the severity of the greenhouse effect and climate change. Unfortunately, increased carbon dioxide alters the chemistry of the water and lowers the pH making it more acidic. The average pH in the upper layers of the ocean has dropped from 8.21 to 8.10 units since the industrial period (Wilkinson, 2008). If the pH continues to drop, the concentrations of dissolved carbon dioxide, bicarbonate ion, and carbonate ion will drop and reduce the ability of organisms to form calcium carbonate skeletons and will eventually dissolve. The increase in carbon dioxide concentrations continues to accelerate faster than anyone had previously predicted (Eakin et al, 2008).
Coral reefs contain an organism called zooxanthellae that live within the coral. Coral and zooxanthellae depend on each other. The zooxanthellae receive nutrients, carbon dioxide, and an enemy-free shelter from the coral, and the zooxanthellae provides coral with food, oxygen and color (Bruno, 2008). Zooxanthellae contain various photosynthetic pigments giving the coral different colors. Bleaching describes the loss of zooxanthellae by the coral exposing its white calcium carbonate skeleton. Coral reefs provide shelter for over 25% of all marine life, (Holloway, n.d) and they depend on the bright colors of the coral to defend themselves from harmful predators. Coral reefs also provide habitat for many of the fish and invertebrate species that feed a substantial proportion of the world’s population. Bleaching is a stress response brought on by various conditions but more frequently by rising sea temperatures (Aronson, Buddemeier, & Kleypas, 2004). If the temperature was raised just 1ºC above normal seasonal temperatures, the heat would damage and break down the zooxanthellae and then are expelled from the coral (which is its main source of energy), leaving it colorless (Bruno, 2008). If temperatures decrease back to normal quickly enough the bleached coral has time to recover, but it could take up to a year (Goreau, & Hayes, 2008). If coral undergoes stress for a prolonged period of time they will be unable to reproduce, defend themselves, and would eventually die in large numbers.
Diseases of corals are having significant negative impacts on the structure and the appearance on coral reefs (McClanahan, n.d). Some coral reefs are attacked by viruses, others by fungi and bacteria. High sea temperatures stressed reefs throughout the world and provide a breeding ground for virulent strains of fungi and bacteria, which resulted in corals being more susceptible to disease. About 30 diseases of corals have been recognized since they were first discovered. “Three coral diseases–“white-band,” “black-band,” and “plague”–were first reported in the Caribbean in the 1970s” (McClanahan, n.d, p. 1), are the most common and deadly types of disease among coral reefs. The black band infection looks like a small black line. The coral in front of the progressing band is healthy, while behind it the coral is dead and looks white. The band’s color comes from concentrations of bacteria that produce sulfur compounds and low-oxygen conditions, which kill the coral (Meichel, Mills, Richardson, & Viehman, 2006). White band and plague are characterized by a spreading lesion of white skeleton. The various types are distinguished by which species they infect, how quickly they spread, and the pattern of spread exhibited (Bythell, Pantos, & Richardson, 2004). Scientists are only beginning to understand the dynamics of infection and resistance and it is only going to get worse if sea temperatures continue to rise.
Scientists have proven over the last century that global warming is happening. They now need to figure out how to stop global warming and reduce the amount of fossil fuels we are burning everyday. If global warming continues to happen, there is going to be too much carbon dioxide in the atmosphere and the ocean will not be able to absorb anymore. Some carbon dioxide is good for marine life, but too much is deadly. Global warming raises the oceans temperature and will cause the oceans pH to lower, which will result in the oceans water being more acidic. Zooxanthellae cannot live in warmer water temperatures. They provide oxygen to coral and are needed for coral to be able to survive. Without the zooxanthellae providing oxygen to the coral, it then becomes bleached and will eventually die. With coral becomes bleached, it means that it is stressed. Once coral is stressed and bleached they are no longer able to reproduce, or defend themselves. If you are not able to defend yourself, then their immune system is compromised and will be easily attacked by diseases. This is why we need to reduce global warming because not only do humans rely on coral reefs for revenue, hundreds and thousands of marine life also relies on coral reefs for food, and shelter.