It also references the back to back coral bleaching events which have devastated the reef and says climate change remains the most serious threat to the entire structure.
The results show the extent to which people have come to depend on the Unesco World Heritage Site. They range from Stonehenge to the pyramids to Greenland's most dramatic fjord, but also include many marine areas containing particularly extensive coral reefs.
Deloitte performed a six-month analysis, consulted scientific research and surveyed 1500 people from 10 countries to calculate that value.
But it ascribes nearly as much - $24 billion - to Australians who are yet to see it, but value knowing that it exists.
It's home to thousands of species... "Our goal was to document climate impacts on World Heritage-listed coral reefs to date, and examine what the future may hold".
"But we've been able to look at it as an "asset" that has incredible value on multiple fronts - from its biodiversity and job-creating potential to its support for critical industries and standing among global visitors to Australia", he said.
But over half the reef is at imminent risk of dying...
"Drastic reductions in Carbon dioxide emissions are essential - and the only real solution - to giving coral reefs on the World Heritage List a chance to survive climate change", the report said.
"We know the frequency and intensity of coral bleaching events will continue to increase as temperatures rise", said Dr. Scott Heron, NOAA Coral Reef Watch and lead author of the assessment. About half of the coral throughout the whole body is now bleached.
Bleaching occurs when coral is "stressed", which is often caused when the water temperature becomes particularly hot.
Best follows up OBE with Lions captaincy
The Maori ran the ball with less abandon than expected and couldn't get their attack going, bar a breakaway try for Liam Messam. Kaino dismissed Lions head coach Warren Gatland's suggestion two days ago that Hansen might be anxious leading into the Tests.
Coral communities typically take 15 to 25 years to recover from mass bleaching.
So how much is $42 billion? It has committed almost two billion dollars to protect the reef. It contributes A$6.4 billion directly to the nation's economy annually.
Apparently, quite easily. And for the record, it's $56 Billion.
It roughly matches the market values of major auto companies around the world, like GM, Honda and BMW.
That's more than 12 Sydney Opera Houses - or represents over four times the length of the Great Wall of China in A$100 notes, if you want to get abstract.
The livelihoods and businesses it supports across Australia far exceeds the numbers supported by many industries we would consider too big to fail, ' says the report, prepared for the Great Barrier Reef Foundation.
"This report sends a clear message that the Great Barrier Reef - as an ecosystem, as an economic driver, as a global treasure - is too big to fail".
"You're looking at some potentially unfolding human tragedy over the decades if reefs can not provide the same source of livelihood", Sean Connolly, program leader of a government-funded coral reef center at James Cook University, Queensland, told CNN in March.
But report after report has highlighted the danger the reef is in, with scientists telling CNN earlier in the year the amount of damage was "unprecedented".
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