A study reveals significant erosion in the coral of the Great Barrier Reef, which is the world's largest single structure made by living organisms.

Scientists believe that this damage is a direct result of changes in water temperatures, along with pollution. In 2016, a study netted similar results.

However, this time round, researchers were able to measure the extent of the damage. They surmised that the changes in temperature since 2016, substantially affected roughly 900 miles of the structure.

Great Barrier Reef Under Threat

Scientists performed an aerial survey off the coast of Australia, the home of the largest coral reef structure on the planet, and found dire results. This is the first time in recorded history that damage has been reported in consecutive years.

Researchers shared that coral in the 1400-mile long structure have died because of "bleaching". In 2016, coral bleaching occurred as a result of a massive El Niño. However, in 2017, the bleaching has hampered the coral even without the periodical weather phenomenon.

Robert Richmond, a coral reef expert at the Kewalo Marine Laboratory in Hawaii, said that these results are "daunting."

"These massive bleaching events have become more severe, are longer lasting and are coming closer together. There just is no question that this is tied to climate change," he added.

Why Bleaching Occurs?

Bleaching is the process when the symbiotic algae inside the coral are released as a result of pollutants, extremely hot waters, and exposure to excessive sunlight. However, bleaching does not kill the coral instantly. The coral can be saved if the water temperature drops significantly and the algae return to its host.

This is the fourth time in two decades that bleaching has been recorded. Previously, the phenomenon affected the Great Barrier Reef in 1998, 2002, and 2016.

In 2016, the bleaching recorded was the most-severe ever. It was revealed that around 67 percent of the coral were affected along a 500-mile stretch near Cairns, Australia.

This year, the central region of the reef was reported to be the most affected. Scientists found that nearly 400 miles of the Great Barrier Reef were suffering from the effects of severe bleaching.

However, scientists believe that if the temperature of the ocean dips a little, the Great Barrier Reef may recover as the coral are known to be resilient and can adapt to a changing environment.

Researchers also revealed that it takes around 10 years for coral to completely recover from the effects of bleaching. However, given that the phenomenon is taking place continuously, the coral are unable to get the time to recoup.