20,000 years ago, as the snows of the last ice age melted away, something magical formed on Australia’s coast. Originally just a few independent coral populations, Australia’s Great Barrier Reef eventually grew to 2,900 reefs; encompassing 900 islands stretched over 133,000 sq. miles. Nestled in the aquamarine waters of the Pacific Ocean, it has long been a destination for tourists, researchers, and beachgoers.
However, as the global temperatures of the world climb, a shadow has crept over this uniquely beautiful vista. Nowadays, the brilliant greens, blues, and reds have begun to fade, replaced by a skeletal white. What is happening to the Reef? What does this say about its future?
A Grim Outlook
Every five years, the Great Barrier Reef Marine Park Authority (GBRMPA) releases an outlook report on the state of the Reef. Considered to be “a consensus of opinion from a broad base of extensive experience and capability independent of GBRMPA”, the 2014 report made headlines with its publication. Of 53 components of the reef system assessed, half were considered “substantially degraded… than would be the case if there had been no significant human impacts in the Region”. Worse still, in the areas categorized in the bottom 10% from the previous survey, almost all had substantially degraded.
Examples of this degradation vary, but almost all trace back to one thing: the bleaching of corals. Justin Marshall, professor at the University of Queensland, explains that the bleaching phenomenon comes from changes in ocean temperature.
“When they become stressed,” Marshall states, “they expel their colourful symbiotic algae that provide them with energy, becoming pale or white. Unless the water temperatures quickly return to normal, many of those organisms die.”
When many corals give up their algae at once, scientist refer to this as mass bleaching. Fortunately, with enough time, coral reefs can bounce back from a mass bleaching event. Unfortunately, this recovery window keeps getting smaller.
Since the 1980s, when monitoring of global coral populations began, three mass bleaching events have occurred: in 1998, in 2010, and in 2016. This year’s bleaching was thought to have been kick-started by El Nino. However, the underlying blame resides with the global temperature increases brought about by human-caused climate change.
In a statement released to the public after this year’s bleaching event, BBRMPA chairman Russell Reichelt stated that “22% of the coral along the length of the reef appeared to be dead”. Most of the southern end remained seriously unaffected, but the northern end had some areas suffering a mortality rate of over 85%.
The nasty thing about coral bleaching resides in the fact that it creates a negative feedback loop in the environment. Earlier this month, Justin Marshall performed multiple diversity surveys around Lizard Island, located on the northern end of the Reef.
Many Barrier Reef species, such as the humbug damselfish, were completely absent. The green chromis, previously one of the most common sights around Lizard Island, was reduced to a single school. Some of the corals were still bleaching, regardless of the cooler waters being brought up from the south. Marshall’s diagnosis: “They’re just holding on by the fingernails”.
The alga that corals bleach off acts as one of the primary attractants to reef fishes, and its absence completely changes the environment dynamic. Without a dependable food source, small reef fishes die or move to greener pastures. With them go the larger predator fishes, as well as detritus feeders such as crabs and starfish. Eventually, the bony-white structures are all that remain: a graveyard of coral.
While scientists consider the current ocean temperatures to be something of an outlier, this will not always be the case. Andrew King, another professor from the University of Queensland, believes that “once greenhouse gasses reach levels expected in 2034, temperatures seen this March will be the new average for the Coral Sea.”
If climate change follows its predicted pattern, this massive disruption to the Barrier Reef will become a yearly occurrence. Needless to say, the potential damage would be catastrophic. As climate scientist Wenju Cai somberly puts it, “We never thought the Great Barrier Reef [was] going to die completely by the 2030s. If [the findings are] true it’s a lot faster than we thought.”
What You Can Do
While the threat of the loss of the Great Barrier Reef might seem overwhelming, undertaking several simple practices reduce the impact that climate change will have on the ecosystem.
First, reduce the amount of fossil fuel you use on a daily basis. Since CO2 emissions contribute directly to greenhouse effects, cutting out some car travel goes a long way. Instead, look to public transportation, biking, or walking.
If you want to directly support coral conservation, consider snorkeling or scuba diving at a site where profit goes right back into spreading awareness. Reefs protected by a government agency, such as NOAA in the U.S. would be an excellent place to start.
Finally, in this age of social networking, simply spreading the word about climate change across social media informs people separated from traditional news outlets. I’ve done my part by researching and writing this article. Now you do yours!
Slezak, M. “Agencies Say 22% of Barrier Reef Coral is Dead, Correcting ‘Misinterpretation’.” The Guardian, sec. Environment:3 June 2016 2016. Print.
—. “Great Barrier Reef Bleaching made 175 Times Likelier by Human-Caused Climate Change, Say Scientists.” The Guardian, sec. Environment:28 Apr. 2016 2016. Print.
—. “Sections of Great Barrier Reef Suffering from ‘Complete Ecosystem Collapse’.” The Guardian, sec. Environment:21 July 2016 2016. Print.
Ward, T. The Rapid Assessment Workshop to Elicit Expert Consensus to Inform the Development of the Great Barrier Reef Outlook Report 2014. Perth: Great Barrier Reef Marine Park Authority, 2014. Print.
“Ways to help coral reefs.” www.nature.org. 2016. Web. <http://www.nature.org/ourinitiatives/habitats/coralreefs/ways-to-help-coral-reefs/>.