Australia's Great Barrier Reef is suffering a "mass bleaching event"

The reef is located in the Coral sea

The world's largest coral reef system, stretching for more than 2,300 kilometers (1,400 miles) over an area of approximately 344,400 square kilometers. The reef is located in the Coral Sea, along the north east coast of Australia, separated from the coast by the channel 100 miles wide in places and over 200 feet deep is showing the effect of the heat, said the Reef Authority. 

The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organism. This reef structure is composed of and built by billions of tiny organism, known as Coral Polyps. 

It supports a wide diversity of life and was selected as a world Heritage Site in 1981. CNN labelled it one of seven natural wonders of the world in 1997. A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit the impact of human use, such as fishing and tourism. 

Aerial survey showed coral bleaching at multiple reefs across a large area of the system, "confirming a mass bleaching event, the fourth since, 2016," said a report by the reef authority, which manages the world's largest coral reef system. 

The Great Barrier Reef, home to some 1,500 species of fish and 4,000 types of mollusc, was suffering despite the cooling effect of the La Lina weather phenomenon, which is currently influencing Australia's climate, the authority said. 

It occurs when corals expel algae living in their tissues, draining them of their vibrant colors. Though bleached corals are under stress, they can still recover if conditions become more moderate. 

"Weather patterns over the next couple of weeks continue to remain critical in determining the overall extent and severity of coral bleaching across the Marine Park." 

The mass bleaching report emerged 4 days after the United Nations started a monitoring mission to evaluate whether or not the World Heritage website is being protected against local weather change. 

UNESCO's mission is to assess whether the Australian Government is doing enough to address threats to the Great Barrier Reef including climate change before the World Heritage Committee considers listing it as "in danger" in June. 

When the UN previously threatened to downgrade the reef's World Heritage listing in 2015, Australia created a "Reef 2050" plan and poured billions of dollars into protection. 

Amanda Mckenzie, cheif executive of Australian Climate action body the Climate Council, said the World's ocean reached record high temperatures last year.