The agency said more bleaching was being observed in the central part of the reef, which a year ago escaped widespread severe bleaching.
Corals have a symbiotic relationship with a tiny marine algae called "zooxanthellae" that live inside and nourish them.
Dr. Neal Cantin from the Australian Institute of Marine Science claimed that bleaching affected the Great Barrier Reef as a result of the high temperatures of the water which were increasing by one degree during an average summer. Algae is already beginning to overgrow numerous corals. Also, there is no way to know how many could recover as algae have been overgrowing on numerous corals already.
Coral bleaching is the event in which the symbiotic relationship between the algae and the coral is damaged, and the algae are lost, leading the coral to lose its colorful pigment and subsequently die.
"This is unfolding as the fourth major bleaching of the Great Barrier Reef since 1998, so the cumulative impact of all four of those events is very serious".
Greenpeace Australia Pacific today released shocking photos and footage documenting the Great Barrier Reef's first severe coral bleaching to happen two years in a row. "In many areas, people are causing declines in coral reefs because of pollution, overfishing, and habitat destruction", he said. The corals aren't getting the chance to bounce back from last year's bleaching event.
"There is no doubt that if we do not get our act together globally we will have serious damage to the barrier reef, we could see the barrier reef lose a huge amount of biodiversity, when you look at the Cayman islands they have about 30 species of coral and we have 300".
Dr Cantin said the "extent and severity" of this year's bleaching would not be known for another month.
'We are extremely concerned moving into the future'.
The second consecutive coral bleaching incident is bound to scar the reef permanently. It requested that Australia deliver an annual report on the reef's health, ensure it meets commitments for greenhouse gas emission reduction as per the Paris Agreement and pledge not to support any development projects that might harm the reef.
The Australian and Queensland governments, which are obliged to show how they are jointly managing the reef's long-term conservation, acknowledge climate change is its main threat. Yesterday's survey of the central third of the Reef's length revealed severe bleaching; this area largely escaped last year's event, according to the GBRMPA.