One of the greatest wonders of the world, The Great Barrier Reef, is now in even more danger. New aerial surveys revealed that more than two-thirds of the Great Barrier Reef is now experiencing intense coral bleaching, scientists say.

This time, it's a back-to-back bleaching phenomenon since last year the site experienced an intense coral bleaching as well. This particularly shocked marine scientists as it's the first time coral bleaching events occurred so close together.

Dr. James Kerry at James Cook University told CNN in a statement: "I was surprised to have to be getting in a plane again this year [to survey fresh damage]. The central section of the reef is now displaying the same extent of bleaching as in the north." He added, "Going over those reefs this year, you can tell how low the coral cover was. It was shocking to see the fallout from last year's event."

Global warming is said to be the main cause of this natural catastrophe. Coral bleaching happens when the sea temperature rises to exorbitant amounts, turning the reefs white and expelling the algae that grow inside the coral. Although the corals can still recover from this event if the sea temperature cools to normal, recent temperatures show that this is not likely to happen.

It's been two decades since The Great Barrier Reef has been experiencing this deadly calamity, according to New York Times. Although scientists have expected the worst to happen because of all the irresponsible practices mankind does that contribute to global warming, they are shocked because this kind of destruction is not expected for another 30 years.

About 1,500 km (900 miles) stretch of the reefs is now affected by coral bleaching. Only the bottom section of the reef is surveyed to have escaped significant damage from the bleaching.

Home to thousands of species of fish and other marine life, the Great Barrier Reef will soon completely die if necessary measures will not take place. $3.7 billion of revenue in tourism and fishing annually is brought by the reefs to the Australian government.