Located off the coast of Queensland, Australia, the Great Barrier Reef is the largest coral reef system on Earth. It extends across an area of approximately 133,000 square miles/344,400 square kilometers and comprises more than 2,900 separate reefs. A World Heritage Site since 1981, it can be seen from space and is an Australian icon on par with Ayers Rock, or Uluru. It is home to more than 9,000 marine species (many of them endangered), and generates approximately $6 billion through tourism and fisheries every year.
Despite its status as a national treasure, the Great Barrier Reef has been plagued in recent years by a number of human and environmental factors — including overfishing, pollution and climate change. In 2012, a paper published by the Proceedings of the National Academy of Sciences estimated that the reef system had already lost half of its initial coral cover. Today, in the wake of two more recent coral bleaching disasters, scientists are now querying whether or not the largest single structure built by living organisms has a future.
The Latest Developments
In April 2017, multiple news sources reported that the Great Barrier Reef was on its deathbed following a major bleaching event in the middle third of the reef system. The damage was documented by an aerial survey carried out by the Australian Research Council’s Centre of Excellence for Coral Reef Studies, which reported that of 800 reefs analyzed, 20% showed coral bleaching damage.
These somber findings came on the heels of an earlier bleaching event in 2016, during which the northern third of the reef system suffered a 95% loss of coral cover.
Together, these back-to-back bleaching events have wreaked catastrophic damage on the upper two thirds of the reef system, the extent of which is only now becoming apparent.
Results from a scientific paper published in the journal Nature in April 2018 show that on average, one in three Barrier Reef corals died over a nine month period following the 2016 and 2017 bleaching events. Similarly, a recent report from the Australian Institute of Marine Science shows that total coral cover has decreased from 22% in 2016 to 14% in 2018.
Understanding Coral Bleaching
In order to understand the severity of these events, it is important to understand what coral bleaching entails. Coral reefs are made up of billions of coral polyps — living creatures that depend on a symbiotic relationship with algae-like organisms called zooxanthellae. The zooxanthellae are afforded protection by the coral polyps’ hard outer shell, and in turn they provide the reef with nutrients and oxygen generated through photosynthesis. The zooxanthellae also give the coral its bright color. When the corals become stressed, they expel the zooxanthellae, giving them a bleached white appearance.
The most common cause of coral stress is increased water temperature. Bleached coral is not dead coral — if the conditions that caused the stress are reversed, the zooxanthellae can return and the polyps can recover.
However, if the conditions continue, the polyps are left vulnerable to disease and are unable to grow or reproduce effectively. Long-term survival is impossible, and if the polyps are allowed to die, the chances of the reef’s recovery are similarly bleak.
Global Causes of Coral Bleaching
The primary cause of coral bleaching on the Great Barrier Reef is global warming. Greenhouse gases emitted by the burning of fossil fuels (both in Australia and internationally) have been accumulating since the dawn of the Industrial Revolution. These gases cause heat generated by the sun to become trapped within the Earth’s atmosphere, raising temperatures both on land and in oceans all over the world. As the temperatures rise, so coral polyps like those that make up the Great Barrier Reef become increasingly stressed, ultimately causing them to expel their zooxanthellae.
Climate change is also responsible for a change in weather patterns. The effects of the 2016 and 2017 bleaching events were compounded by Cyclone Debbie, which caused significant damage to the Great Barrier Reef and the Queensland coast in 2017. In the wake of the disaster, scientists predicted that the Coral Sea will see fewer cyclones in the years to come - but those that do occur will be of a much greater magnitude. The damage caused to the area’s already vulnerable reefs can therefore be expected to worsen proportionately.
Local Factors Also at Fault
In Australia, agricultural and industrial activity on the Queensland coast are also contributing significantly to the reef’s decline. Sediment washed into the ocean from farms on the mainland suffocates the coral polyps and prevents the sunlight needed for photosynthesis from reaching the zooxanthellae. Nutrients contained in the sediment create chemical imbalances in the water, sometimes triggering harmful algal blooms. Similarly, industrial expansion along the coastline has seen major disruption of the seabed as a result of large-scale dredging projects.
Overfishing is another major threat to the future health of the Great Barrier Reef. In 2016, the Ellen McArthur Foundation reported that unless current fishing trends change dramatically, there will be more plastic than fish in the world’s oceans by 2050. As a result, the fragile balance that coral reefs depend upon for their survival is being destroyed. On the Great Barrier Reef, the damaging effects of overfishing are proven by repeated outbreaks of crown-of-thorns starfish. This species has spiraled out of control as a result of the decimation of its natural predators, including the giant triton snail and the sweetlip emperor fish. It eats coral polyps, and can destroy large tracts of reef if its numbers are left unchecked.
The Future: Can it Be Saved?
Realistically, the outlook for the Great Barrier Reef is poor — so much so that in 2016, Outside magazine published an “obituary” for the reef system, which swiftly went viral. However, while the Great Barrier Reef is certainly sick, it isn’t yet terminal. In 2015, the Australian government released the Reef 2050 Long-Term Sustainability Plan, designed to improve the reef system’s health in an attempt to save its status as a UNESCO World Heritage Site. The plan has seen some progress — including a ban on dredging material being dumped in the World Heritage Area and a reduction of pesticides in agricultural run-off by 28%.
In the wake of 2018 reports on the reef's deteriorated health, the government announced its decision to invest nearly half a billion Australian dollars into increasing the reef's resilience through a partnership with the Great Barrier Reef Foundation. The partnership will adopt a multi-faceted approach to the problem, focusing on goals such as improving water quality, addressing crown-of-thorns starfish outbreaks and finding ways to help reefs that have already been bleached to recover.
On an international level, the Trump administration’s decision to withdraw from the Paris Agreement in 2017 was seen by many as proof that global emissions will never be reduced enough to see a meaningful decrease in worldwide sea temperatures. Without several decades of optimum coral-growing conditions, it seems unlikely that the Great Barrier Reef can recover. On the other hand, every other nation (with the exception of Syria and Nicaragua) did sign the agreement, so perhaps there is hope that the effects of climate change can be reversed, or at least mitigated.
The Bottom Line
So, with all that in mind, is it still worth traveling to the Great Barrier Reef? Well, it depends. If the reef system is your sole reason for visiting Australia, then no, probably not. There are many more rewarding scuba diving and snorkeling destinations elsewhere - look to remote areas like eastern Indonesia, the Philippines and Micronesia instead.
However, if you’re traveling to Australia for other reasons, there are definitely some areas of the Great Barrier Reef that are still worth checking out. The southernmost third of the reef system is still relatively intact, with areas south of Townsville escaping the worst of the recent bleaching events. In fact, studies from the Australian Institute of Marine Science show that the southern sector corals are remarkably resilient. Despite the increased stress factors of the last decade, coral cover has actually improved in this area.
Another good reason to visit is that the income generated by the Great Barrier Reef’s tourism industry serves as a major justification for ongoing conservation efforts. If we abandon the reef system at its darkest hour, how can we hope for a resurrection?