Coral bleaching in Maldives, similar to that in the Great Barrier Reef.

March 6, 2017

Wanted: Great Barrier Reef, Alive

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In October 2016, an article began circulating social media outlets with the headline “Obituary: Great Barrier Reef (25 Million BC-2016),” announcing the abrupt death of one of the most diverse and complex ecosystems in the world. Understandably, ecologists and nature enthusiasts alike cried out in alarm. The pinnacle of environmental beauty that had made it into every introductory ecology textbook had passed away, another casualty to the seemingly unstoppable force of climate change.

There is no doubt that action needs to be taken immediately if humans ever hope to impede the potentially disastrous effects of climate change, however those who use the recently ‘deceased’ Great Barrier Reef as their first piece of evidence are missing one critical detail.

“The Great Barrier Reef definitely sustained some of the biggest impacts its seen from warming events, but it’s definitely not dead,” said Prof. Drew Harvell, ecology and evolutionary biology. “It’s kind of like saying if half the trees in a forest died, the forest is dead.”

Harvell has studied coral reefs all over the world and while the Great Barrier Reef is by no means immaculate, there are particular areas where corals have been even more severely bleached from rising temperatures, ocean acidification and increased predation.

“Coral bleaching is the breakdown in symbiosis between the coral animal and its symbiotic algae,” Harvell said.

Within coral, there are two species working together: algae, which uses photosynthesis to make food from sunlight and the coral animal, which houses the algae. “Corals are solar powered, basically,” Harvell said.

Unfortunately for corals, when temperatures are too high, the coral animal becomes stressed and releases its algae. The algae gives corals their vibrant colors and without them, corals turn white, a process known as coral bleaching. Having lost their main provider of food, corals may die shortly after.

According to Harvell, the northern sector of the Great Barrier Reef has recently been hit the hardest with bleaching.

“It was estimated to have been over 80 percent severely bleached,” Harvell said.

Harvell pointed out that coral cover in that area, which used to be 40 percent, has dropped to less than 10 percent. The central and southern sectors of the reef, though still heavily damaged, have been relatively spared and only one percent of corals in the southern sector were severely bleached.

This is not the case for many of the pristine coral reefs found throughout the Pacific island nations. In 2016, an El Niño related event increased temperatures for this region by two to five degrees celsius, resulting in the death of 90 percent of the corals in those reefs. Harvell emphasized that this 90 percent represented mortality, not bleaching.

El Niño is not a new phenomenon; it is a climate oscillation in the Pacific Ocean that occurs roughly every three to seven years, bringing anomalous weather and temperatures with it. However, the strength of the 2016 El Niño event was likely magnified by increasing global temperatures.

While the cause of climate change will continue to be debated amongst politicians, the majority of earth and atmospheric scientists have made it clear that it is human-driven and not slowing down anytime soon. The five hottest years since 1880? 2016, 2015, 2014, 2010 and 2013.

“If you’re 29 or younger, no month of your life has had below average global temperatures,” Harvell said. “It’s awful to think this generation has lived with warming impacts for their whole lives. It blows my mind that this is normal.”

Without these rising temperatures, coral reefs around these Pacific islands may recover, albeit slowly. Unfortunately, humans cannot expect the Earth to get cooler anytime soon.

“Given that the last three years have each successively been the warmest year on record, I think the prospect of another warm year in the next five years are pretty good,” Harvell said. “Reefs are really amazingly resilient, but they can’t sustain biodiversity with repeated hot years.”

As corals begin to die off, so do the ecosystems they support, impacting marine life and humans alike. Along with habitat loss for fish that are important for local fisheries, damaged corals fail to act as wave breaks in low-lying island nations surrounded by reefs. This makes these islands more susceptible to tsunamis and powerful storm surges.

It is easy, in the face of such bad news regarding the health and state of global corals, to pronounce the Great Barrier Reef dead. It seems as though dramatic gestures and absolute headlines are the only options to get people to act instead of sitting idly by. But despite this temptation, we must predicate their desire to fight with facts as opposed to feelings. Facts tell us that strides are being taken towards preserving the corals that are still alive.

Harvell notes that the aforementioned article’s headline, although incorrect, likely had good intentions. However, announcing its death makes saving coral reefs appear to be a lost cause, instead of a challenge that scientists and politicians have begun to take on. Last year, the third annual Our Oceans conference, hosted by then-Secretary of State John Kerry, reiterated the importance of marine protected areas to protect fragile marine environments. It also highlighted new technology and ideas to reduce marine pollution, overfishing and carbon dioxide emissions.

As for what Cornell students can do to help coral reefs? Harvell does not limit the possibilities, but gave one main suggestion.

“In the end, I find that education is one of our most important tools and if Cornell students could spread what they learn to their families, it could make a big impact,” Harvell said.

Coral reefs throughout the world, though damaged by direct and indirect human activity, are not gone. As long as there are well informed leaders and citizens, the Great Barrier Reef’s obituary will have to wait.