In 2016, the Great Barrier Reef saw the worst bleaching event on record — two-thirds (67%) of corals in the northern sector of the reef died after being exposed to unusually warm currents. While experts warned that these bleaching events would continue to happen with more frequency as global temperatures rose, no one expected to see it happen two years in a row.
In a new aerial survey covering more than 8,000 kilometers (5,000 miles), researchers found that 1,500 kilometers (or 932 miles) of the Great Barrier Reef has been bleached. Whereas last year’s bleaching affected the northern part of the reef, this latest damage is concentrated in the middle section, and has extended farther south than ever before.
Though there have been a handful of other significant bleaching events in the past two decades, this marks the first time it’s known to have happened in two consecutive years. Because of the proximity of the two events, experts fear the damaged coral will have little chance to recover.
“It takes at least a decade for a full recovery of even the fastest-growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016,” according to ARC Centre of Excellence for Coral Reef Studies senior research officer James Kerry.
What’s to Blame?
Bleaching is the result of unusually warm waters stressing the corals to the point that they eject the photosynthetic algae, called zooxanthellae, from their cells. This algae not only gives the corals their brilliant color, it provides them with crucial nutrients and removes waste. Without the zooxanthellae, the corals are more vulnerable to disease and starvation. If normal conditions return, the corals can recolonize the algae and recover. However, if the stress continues, the corals can die.
The previous four severe bleachings of the Great Barrier Reef occurred in 1998, 2002, 2006 and 2016 — all El Niño years wherein the world saw unusually warm ocean currents. What’s especially concerning is that 2017 is not an El Niño year. This means that, to the experts’ absolute horror, the reef is now bleaching in both non-El Niño years and in consecutive years.
Though El Niño has typically been a naturally occurring climate phase, it’s been exacerbated by anthropogenic climate change. Since humans began emitting carbon pollution, the world has warmed roughly 1.8°F (1°C). This warming is projected to continue, and scientists predict that coral will likely go extinct if the world reaches the 2.7°F (1.5°C) mark.
Robert Richmond, a coral reef expert and director of the University of Hawaii’s Kewalo Marine Laboratory, told National Geographic that the data was “daunting.”
“These massive bleaching events have become more severe, are longer lasting and are coming closer together,” he said. “There just is no question that this is tied to climate change.”
Why Should We Care?
This bleaching is more than just a bummer for tourists looking to snap underwater pictures of brightly colored coral. The Great Barrier Reef is home to the world’s largest collection of coral reefs, featuring around 400 types of coral. It houses 3,000 varieties of mollusks, more than 100 types of jellyfish, 1,625 species of fish, hundreds of shark and ray species, and 30-plus kinds of whales and dolphins. What’s more, it’s also the main habitat of a number of endangered species, including the large green turtle and the dugong. Without the corals that make up the reef, many of these animals will die.
Recovery of the bleached coral is currently uncertain. Though the full extent of this year’s damage won’t be known until in-water surveys are conducted, Kerry isn’t optimistic. “We anticipate high levels of coral loss,” he said.
Despite the fact that we live in an age of global warming, some world leaders refuse to admit there’s a problem. Without the measures being put in place to limit our emissions, temperatures will continue to rise, bleaching events will continue to happen, and we’ll see even more damage than we already have. It’s a scary thought, but it may well be reality — we might be the last generation to see the true beauty of the Great Barrier Reef.
Feature image courtesy of Shutterstock