The impact of global warming can be seen all over the world. Global warming has a major influence on the planet and the ecosystems our planet supports. One ecosystem in particular is going through drastic changes due to global warming: the coral reefs. Coral reefs are also known as the rainforest of the sea and contain some of the most diverse creatures in the world. As the temperatures rise globally, so do the ocean temperatures. The increase in water temperatures due to global warming is resulting in coral reef bleaching and the overall decline of coral reefs. 

Coral reef bleaching is the product of increased ocean temperatures. Corals only require a sustained temperature increase of one degree Celsius to upset them and cause stress (Worland). Coral bleaching is caused by stress that is triggered from changes in the environment (US Department of Commerce). Environmental stress can come from variations in temperature, light, or nutrients (Warm). This stress causes the corals to expel colorful algae living inside of them and leaves corals with a pale white color (US Department of Commerce). Coral bleaching does not mean the coral is dead, it simply means that the corals have lost their main food and energy source (US Department of Commerce). Bleached coral can recover, but it is a long process that depends on the corals not experiencing any more environmental stresses, such as pollution (Slezak). Bleaching leaves the corals fragile and weak which makes them more prone to disease. Coral diseases make it harder for the bleached coral to recover, and can ultimately result in death (US Department of Commerce). After the coral has died, the ecosystem it supports struggles to survive. The death of the coral allows the reef to be taken over by seaweed which then surrounds the coral and prevents marine animals from using it as a shelter. Fish and other animals use corals for both shelter and a food source. Once the coral has died they are forced to move elsewhere to live or end up dying off. The effects of the dead coral ripple down through the entire food chain (Slezak). It is impossible to fully explain the importance of coral reefs. They are home to a quarter of the ocean’s marine life. They support tourism and fishing industries, and they are extremely helpful during storms. Coral reefs provide protection to coastlines from flooding during tropical storms(Worland).

Coral bleaching is not an isolated event either. Bleaching events are episodic, and have happened annually since the 1980’s. The most severe bleaching episodes happen after the corals sit in calm warm water for too long and are usually accompanied by ocean atmosphere-phenomena like El Niño (Baker). El Niño is a surge of warm water that disperses across the Pacific Ocean. This phenomenon occurs on irregular intervals, and usually happens once every five years. El Niño warms the world and its oceans, and therefore, extreme bleaching episodes happen during this time period (Slezak). Coral reef bleaching used to be an extremely rare incident. The first recorded bleaching event occurred in 1911 on Bird Key Reef in the Florida Keys (Slezak). Scientists assume that minor bleaching events happened in small patches but were never recorded before this time. The bleaching event in 1911 happened during a time of calm and hot weather (Slezak).  Another small bleaching event was reported in 1929 on the Great Barrier Reef (Slezak). Following this event was a period of silence for the next few decades, until 1979. The first time the term “mass bleaching” was used was in 1979. A bleaching event took place that year hitting the coral reefs from the Florida Keys to the Caribbean. This was the first-time coral bleaching was seen destroying large regions rather than small isolated stretches of coral. Mass bleaching events have now been recorded every year since. Something that was once rare and unheard of is now being seen every year, and every year the severity of the bleaching events increase (Slezak). 

Mass bleaching was once the scariest terms used to describe a coral reef bleaching event, but as coral bleaching started spreading rapidly, to every part of the world, the new phrase “global coral bleaching” took its place. The first ever global coral bleaching event was in 1998, followed by a second event in 2010 (“NOAA”). We are still experiencing the third global coral bleaching event right now. The third event began in 2014 in the North Pacific Ocean. This bleaching event is the longest ever recorded. This has had a devastating impact on the corals, because they have not had enough time to recover. Corals can recover from bleaching if the period is short, but when exposed to long term bleaching, the corals will most likely die off (“NOAA”). Scientists at NOAA are pushing for local governments to prevent any extra harm to the corals, such as overfishing and littering, that can make it harder for reefs to recover from long term bleaching. This is just a short-term solution, however, and if the global problem of coral bleaching is to be stopped, scientists must come up with a way to reduce the excessive carbon dioxide output that causes global warming (“NOAA”). 

The Great Barrier Reef is the most well-known coral reef in the world, mainly due to its size. It is the largest coral reef ecosystem on the planet covering more than 133,000 miles. Thousands of unique creatures call it home, including the corals. Almost a quarter of the ocean’s marine life call coral reefs their home (Worland). The importance of the Great Barrier Reef is astounding. Alone, this amazing ecosystem contributes more than 3 billion dollars each year to the Australian economy (Howard). The reef pulls in tourists from all over the world that contribute to the economy (Worland). This reef has been hit particularly hard by the effects of coral reef bleaching. Divers surveying the corals in 2016 discovered that up to 50% of the corals in the reef are dying due to coral reef bleaching (Howard). The northern tip experienced the worst of the die off, due to the hot and still conditions that the corals were forced to sit in for months. The northern part of the Great Barrier Reef is considered to be the most unspoiled portion of the reef, and this latest bleaching event is the worst to hit this section (Howard). Divers surveying the northern tip found that some atolls had completely died off (Innis). Luckily, a cyclone that reduced ocean temperatures saved the lower part of the reef from the same damage (Innis). Only 1% of the coral in the southern part of the reef has died this year but about two thirds of the coral in the north did not survive this latest bleaching event (Innis).

 In response to the mass bleaching happening here, the Australian government was forced to issue its highest response level in hopes of stopping this tragedy (Howard). The new level three response requires intense surveying of the reef to be aware of any more bleaching events (Howard). The Australian government also plans on spending around 45 million dollars to clean up the water quality and reduce runoff from farms and industrial sites (Innis). Scientists have criticized the Australian government for their plans, pointing out the contradictions of their statements. For example, the new Carmichael Coal mine will be the largest coal mine in Australia once complete, and is already causing a huge uproar. Since coal mines produce large amounts of greenhouse gases that are the main cause of global warming, many people are upset with the creation of a new coal mine (Innis). William Steffen, who is a climate scientist at the Australian National University College of Medicine, Biology and Environment, said this about the new budget, “Spending $45 million to improve water quality on the reef is like putting a Band-Aid on a person who has cancer.” Numerous scientists agree with Steffen, and think the Australian government is ignoring the bigger problem plaguing the coral reefs (Innis). 

Increasing ocean temperatures are a huge problem that coral reefs face, but they are not the only problem causing them stress. Another problem the oceans face due to global warming is increased acidity of the water. Carbon dioxide (CO2) is being pumped into our atmosphere at alarming rates, and as more of it is released, more of it dissolves into the ocean (Howard). Increased concentrations of carbon dioxide in the ocean causes the pH of the water to lower, making it harder for reef building corals to survive. Nutrient runoff is another problem plaguing coral reefs. Farms and lawns use industrial chemicals that leak into the ocean and are harmful to the corals (Howard). Overfishing is a threat to the health of coral reefs as well. Many fisherman use a technique where they throw dynamite into the water to catch fish, which destroys corals in the process (McDermott). 

  What is happening to the Great Barrier Reef is just a simple representation of what is occurring all over the globe. Within the last year alone, 12% of the world’s coral reefs have bleached themselves due to extreme heat, and it is predicted that about half of these reefs will not be able to recover and will die (Howard). From Florida to Australia, reefs everywhere are suffering damage due to global warming. Scientists are increasingly concerned because the bleaching events aren’t isolated, rather they are continual, and do not give the corals enough time to recover (Worland). Jennifer Koss, NOAA’s Coral Reef Conservation Program director, explained the situation best, “If you think of corals as canaries [in a coal mine], they’re chirping really loudly right now, the ones that are still alive, that is (Worland).”

Scientists all over the world are desperately trying to come up with ways to save the coral reefs. One scientist, Dr. David Vaughan, is working on improving the health of corals on the Florida reef tract. Dr. Vaughan developed a technique called microfragmenting (“A breakthrough”). Microfragmenting takes a piece of coral and cuts it into a smaller piece about the size of a dime. When the coral is broken into pieces, this stimulates rapid healing inside of the coral, and allows the coral to regrow 25 times faster than it normally would (“A breakthrough”). Once the small pieces of coral become big enough (about the size of a silver dollar), they are replanted on damaged areas of the reef. Dr. Vaughan is currently focusing on the slowest growing species of coral (“A breakthrough”). These slow growing species set the main foundation for reefs, and are a key factor in maintaining reef survival. If Dr. Vaughan’s plan goes as expected, he hopes to have a small reef growing in around 2-3 years (McDermott). While this plan sounds great, there is a huge downside to the microfragmenting technique. Since all the smaller pieces of coral are all grown from one large piece, they all share the same genetic makeup (McDermott). This means that all the coral replanted on the reef will respond the same way to environmental stresses. Naturally grown reefs have different genetic makeup and therefore have different weaknesses.  Researchers can spend years re-growing a small reef just to have it entirely wiped out by a period of thermal stress (McDermott). 

In 2013, a marine scientist named Peter Harrison carried out an experiment on a reef in the Philippines, called Magsaysay, to try and fix the issue of genetic diversity. This reef was extremely damaged due to blast fishing, where dynamite caused huge corals to blow to dust (McDermott). Harrison’s team collected larvae from a fast-growing coral located at a healthy neighboring reef. The group then released the larvae into the damaged reef and waited, hoping that saturating the reef with baby coral would give it a chance to regrow (McDermott). After 6 months, most of the baby coral died. However, when nine months had passed, the remaining new corals survived. Harrison expected most of the new corals to die, but somehow, they have survived, and three years later the once new corals have now reached sexual maturity (McDermott). 

Scientists in Hawaii are trying a different approach to saving the reefs. Ruth Gates is a coral biologist at the Hawaii Institute of Marine Biology. Gates has been searching coral reefs off the coast of Hawaii for corals that appear to be stress tolerant (McDermott). Once found, Gates began running experiments on these “stress tolerant” corals, subjecting them to harsh conditions to see if they survive. The strongest corals from the experiment are then bred to produce the most genetically stress tolerant coral (McDermott). This new coral is then released onto damaged reefs and allowed to grow naturally. Her hope is that reefs will eventually become healthy enough that they will not need outside help (McDermott). 

In conclusion, coral reefs are one of the most beautiful and unique ecosystems in the world. They support a quarter of the ocean’s marine life, and they bring in billions of dollars due to tourism and fishing industries. Coral bleaching is a serious global problem caused by an increase in the ocean’s temperature. Bleaching episodes are happening more frequently and for longer periods of time, making it harder for corals to recover. Coral fragmentation, reseeding, and selective breeding are techniques invented by scientists to try and save corals from dying off. These solutions are not permanent fixes and each comes with its own flaws. Every coral reef is diverse and reacts to different stress in different ways. Therefore, what might be a good solution for one reef will not work for another.  The only permanent solution to solve the global problem of coral reef bleaching would be to somehow reduce the amount of carbon dioxide causing global warming in the first place. Scientists are on the right track, but more progress must be made in order to save the future of coral reefs. 
