Study Shows Crisis for Great Barrier Reef

Coral levels have dropped by half

The coral in Australia's Great Barrier Reef is rapidly disappearing due to a host of factors -- all of which are influenced by humans, according to a new study. The report, published in the Proceedings of the National Academy of Sciences, tracks coral cover over the last 27 years and finds levels have fallen by nearly 50%.

The Great Barrier Reef is one of the world's most beloved natural attractions because of its remarkable array of sea life. But, according to researchers, a trio of factors has conspired to degrade the reef: tropical cyclones, attacks from the coral predator the crown-of-thorns starfish, and rising water temperatures. As a result, coral cover in the area has dropped from 28% in 1985 to 13% today, according to the team, which carried out the largest-ever continuous survey of reef condition for the study.