TRANSCRIPT:
Climate scientists operating underwater with surgical precision.
With a drill - they're funnelling deep into coral within the Great Barrier Reef to remove its core.
Professor Jens Zinke, from the University of Leicester, explains.
"They are actually living sensors, that for us sit in the ocean for hundreds of years, recording what has happened to them over many centuries, during their lifetime."
Resembling long white sticks, they show, even to the naked eye, evidence - of past extreme weather.
"You see this kind of purple band. This is a stress band, most likely formed during a thermal stress event, so this core was drilled in 2018, so this was probably 2010, given the distance from the core here."
Professor Zinke's records were among the trove analysed by researchers in Australia.
When Dr Ben Henley from the University of Melbourne ran the numbers on the waters that take in the barrier reef, he was stunned.
"Sadly, this year was the most extreme sea surface temperature for January to March in the last 400 years in the Coral Sea. Yeah we were really shocked. Until now we didn't have a good understanding of what past centuries looked like in good detail."
Researchers modelled the surface temperature of the coral sea, going all the way back to 1618.
From the 50s onwards - there's a marked upwards trend in temperatures, coinciding with the acceleration of global warming.
2016, 2017, 2020, 2022, and 2024 are among the warmest years on record.
In all of those years - the reef was undergoing mass coral bleaching.
Dr Roger Beeden is the Chief Scientist at the Great Barrier Reef Marine Authority, who says the report provides important context.
"What this is showing us is that , the mass coral bleaching, which is Coral bleaching, or that stress response across large areas of coral reefs, is a modern phenomenon. We have seen it correlate with satellite temperature records over the past couple of decades and getting substantially more frequent and more severe over recent events."
The report's authors say humans are the key influence, and Dr Henley warns bleaching risks are becoming an annual event.
"If we're seeing back to back bleaching events almost every year or every year, that thwarts the attempts by the corals to recover, and that means that the whole structure of the Great Barrier Reef is likely to change in the future."
In June, UNESCO opted not to list the Great Barrier Reef as "in-danger", but the government has to give an update on its health by February.
Environment Minister Tanya Plibersek told SBS Labor understands its responsibility to take the pressure off the marine wonder.
It has pledged $1.2 billion to go into conservation efforts.
Dr Beeden says the government-funded marine authority is working to try and mitigate the impacts.
"The primary focus is trying to reduce those local pressures, things like improving water quality, managing coastal fishing, making sure coastal developments don't encroach on key habitats and most focusing on managing crown of thorn starfish outbreaks. And the reason we're doing all of that is because we're seeing these mounting pressures of climate change."
Human induced global warming currently sits at 1.1 degrees, compared to pre industrial levels.
If it reaches one point five degrees, it's forecast between seventy to ninety per cent of reefs will die.
Helen McGregor is one of the report's co-authors, from the University of Wollongong Report Author - and says the research the case for the UNESCO rating to be reconsidered.
"I think we need to be looking at all reefs as in danger. I mean we’re seeing a mass global bleaching event going on around the planet and that points to all of the reefs being in danger. So the science - we need to verify that that long term contexts in other locations has been said - but the science is pointing very clearly to the reef being in danger. And elevating that status I think is not blaming any particular government, but it's a rally call to the world that we need to be reducing our emissions urgently, immediately.”
