Seawater would be pumped through a filter and sprayed from small jets that produce tiny water droplets.
A fan would drive the droplets into the atmosphere. The water evaporated and left a tiny salt where other water droplets condensed and lightened existing clouds.
Apart from shading the reef, the clouds would also divert the sun's rays and lower the surface water temperature by about half a degree Celsius.
"This one drop produces an aerosol particle that grows 15 million times into a cloud droplet," Dr. Harrison, a researcher from the University of Sydney.
Corals bleach due to a combination of higher temperatures and sunlight, so the effect of the cloud "could be very effective to mitigate bleaching," he said.
The units would have to be run for weeks or months if the coral risk was greatest. The research is at an early stage and has not been tested.
Dr. Harrison said the impending fatherhood had given new impetus to his work.
"My first child is due on Tuesday … I really hope the reef will be there for him as he gets older," he said.
"[Losing the reef] This will not happen in future generations, it is right now in this generation, if we do not act now. It's really scary. "
The project is part of the Reef Restoration and Adaptation Program, which is led by the Australian Institute of Marine Science and brings together experts to develop new, targeted conservation and restoration measures for the reef.
Director of the program David Mead said that while aggressive action against climate change was critical, scientists asked, "What else can we do?"
"We try to assess as broadly as possible what some of the other options might be. [We’re taking] An approach that did not shoot stones, "he said.
One option being investigated is to spread a microscopic film over the water surface to prevent light photons from reaching coral, which reduces the risk of bleaching.
Other research involves collecting elastic corals that survive a bleaching event and use them to repopulate other reefs.
While the risk for the reef was pressing, time would be taken to develop and test the cutting-edge technologies.
"The last thing you want to do is take action where the cure is worse than the symptom," Mr. Mead said.
As the state of the reef deteriorates, there is pressure to develop local and regional interventions in high-value locations such as dive pontoons and reefs with high biodiversity.
Convenor of the Great Barrier Reef Restoration Symposium, Damien Burrows, said the community should also be consulted to determine which areas of the reef should be prioritized for restoration.
Indigenous peoples, the tourism and fishing industry and other recreational users could value the reef for a variety of reasons, and these must be balanced when deciding on interventions, said Professor Burrows.
Nicole Hasham is environmental and energy correspondent for The Age, the Sydney Morning Herald, Brisbane Times and WA Today.
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