Large parts of Great Barrier Reef dead by mid-2030s from climate change

Large parts of Australia's Great Barrier Reef will likely be dead by the mid 2030s as climate change drives the frequency and intensity of mass coral bleaching events, Aussie scientists warned on Friday.

Analysing the current mass bleaching event ravaging the Great Barrier Reef, researchers from the ARC Center of Excellence for Climate System Science found the effects of human-induced climate change had added one-degree Celsius of warming to the ocean temperatures.

But should greenhouse gas emissions continue to increase, this extreme temperature will be come the new normal within 20 years and cause similar mass bleaching events every two years, the as-yet unpublished findings show.

That spells death for large swathes of the Great Barrier Reef as coral bleaching recovery rates are being overwhelmed by more frequent and severe mass bleaching events. Corals need up to 15-years to completely recover from an event.

Though the research is yet to be peer reviewed, the scientists took the unprecedented step of releasing their results early due to the grave nature facing the Great Barrier Reef from inaction.

"We are confident in the results because these kind of attribution studies are well established but what we found demands urgent action if we are to preserve the reef," lead author Dr Andrew King said in a statement on Friday.

"For this reason, we felt it was vital to get our findings out as quickly as possible."

Coral reefs are one of the most important and productive marine ecosystems that the world depends on for tourism and fisheries sustainability.

Coral bleaching occurs when stress such as heat caused the animal to expel the symbiotic algae, loosing vital nutrients and energy reserves, thus color, leading to the wide scale loss of productive habitats for fish.

The coral host then becomes weak and susceptible to disease. When bleaching is prolonged, the animal can die.

Recent research suggests corals with high levels of fat or other energy reserves can withstand annual bleaching events, which is critical to predicting the persistence of corals and their capacity to recover from more frequent events resulting from climate change.