In concluding the troubling findings, between 1995 and 2017, researchers from the ARC Centre of Excellence for Coral Reef Studies in Queensland, Australia, examined the colony size of corals in the world’s largest reef.
What they discovered was extreme depletion across all sizes of coral.
“We found the number of small, medium and large corals on the Great Barrier Reef has declined by more than 50 percent since the 1990s,” Terry Hughes, a coral researcher at James Cook University and senior author of the study, said in a news release.
“The decline occurred in both shallow and deeper water, and across virtually all species—but especially in branching and table-shaped corals.”
Covering nearly 135,000 square miles, these corals in the reef are especially important in providing a habitat for marine life. The researchers noted that losing them would also mean a massive decline in reef biodiversity.
Despite covering less than 0.1 percent of the ocean floor, reefs host more than 25 percent of all marine fish species, according to the International Union for the Conservation of Nature.
The local economy is under threat as well. The Great Barrier Reef Marine Park Authority says that the reef contributes “more than $6.4 billion each year to the Australian economy and around 64,000 full-time jobs.”
According to Hughes, much of the impact on coral depletion can be blamed on mass bleaching events likely triggered by record-breaking ocean temperatures in 2016 and 2017.
“I began surveying the reefs in 1995, and what subsequently unfolded certainly wasn’t planned for,” Hughes told the Guardian. “There have been five major bleaching events since then, including three in just the past five years.”
He added that he was “very concerned” about the “shrinking gap” between bleaching events.
In August 2019, the government agency that manages the Great Barrier Reef downgraded its outlook for the corals’ condition from “poor” to “very poor.”
For Hughes, the only way to save the corals and the reef is to reduce greenhouse gas emissions.
“There’s not much time to lose,” he said. “I think if we can control warming somewhere between 1.5 and 2 Celsius (above pre-industrial levels), as per the Paris Agreement, then we’ll still have a reef. But if we get to 3 to 4 Celsius because of unrestrained emissions, then we won’t have a recognizable Great Barrier Reef.”
Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek, and Arirang TV. Follow or contact him on LinkedIn.