Scientists warn the world heritage site is once again under threat from "an underwater heatwave", threatening the livelihood of half a billion people across the globe.
This year's El Nino have seen up to half of the reeds in some Pacific locations killed by bleaching. The warmer water forces the coral to expel the algae it needs to live.
Professor Ove Hoegh-Guldberg from the Global Change Institute at the University of Queensland said global warming has already had a devastating impact on the Great Barrier Reef.
A before and after image of coral bleaching in American Samoa, with the right image taken in December 2014 (XL Catlin) Source: XL Catlin
“The types of conditions that we're seeing now in the Pacific mirror those that we saw prior to the 1998 [mass coral] bleaching event,” said Ove Hoegh-Guldberg from the Global Change Institute at the University of Queensland.
“And they estimate we lost around 16 per cent of corals during that nine month period.
"So with the similar signs appearing in the Pacific as were seen in 1997. It's almost certain now that we are going to see something similar.”
Researchers fear an "underwater heatwave" could impact close to 40 per cent of the world's reefs, with the potential to wipe out over 12,000 square kilometres of coral.
Ove Hoegh-Guldberg said the damage bill from mass coral bleaching events induced by global warming could amount to a trillion dollars.
“Let's say we wanted to repair the Great Barrier Reef, replant coral, rather than deal with the underlying warming issue,” he said.
“We'd be spending trillions of dollars every couple of decades to maintain coral and the Reef - and even then it probably wouldn't work.”
Young activists fight to protect reef’s ecosystem
Jaden Harris from the Australian Youth Climate Coalition is one a group of activists who has come to Paris to ensure the Great Barrier Reef has a future.
“Young people are obviously the generation who are going to be around when the worst impacts of the decisions made today are felt,” he said.
Paul Gorrie from the Seed Indigenous Youth Climate Network said it is an important issue for Indigenous Australian youths.
“We [Indigenous Australians] were the first scientists and we have been looking after the land for 60,000 years sustainably and we plan to do that for the next 60,000 years,” he said.
A limit of two degrees Celsius on global warming is not enough to ensure the Great Barrier Reef’s future, according to Hoegh-Guldberg.
“The science tells us that two degrees is too much for coral reefs. [A limit of] 1.5 degrees becomes something we probably should be aiming for in the long term.”
