Author – Bernard Lagan, Sydney, April 25 2017, 12:00pm, The Times.
Scientists are looking to the heavens in the latest attempt to save the Great Barrier Reef from the devastating effects of climate change.
Work has begun on plans to enlarge clouds above the reef in what has been described as an 11th-hour attempt to save the coral below. The move comes as fresh studies show that much of the coral on the 1,400-mile-long reef is dead or at risk of dying because of rising water temperatures.
A process known as marine cloud brightening can produce larger and more reflective clouds, which limit temperatures in the water below.
John Latham, a British scientist, first suggested the theory as a potential means of controlling global warming 30 years ago in an article published by Nature. The idea was that fleets of ships could spray tiny salt particles, harvested from sea water, towards low-lying clouds that hug coastlines.
The salt would enlarge the clouds, increase their density and cause more heat from the sun to be reflected back into space.
Drawing in part on Mr Latham’s earlier work, Australian scientists — within the Ocean Technology Group at the University of Sydney — have been examining the application of the technology to the Great Barrier Reef.
Daniel Harrison, a postdoctoral research associate with the group, believes it could work.
“All of our preliminary calculations so far suggest that it is plausible,” Dr Harrison told the Australian Broadcasting Corporation on Tuesday. “You can think about this in very layman’s terms. If you’re in a hot sunny day and a cloud comes across overhead, you can feel right away there’s quite a lot less heat coming through.”
Other scientists working at the Marine Cloud Brightening Project in California have spent the past seven years developing a nozzle that they believe will be able to spray salt particles of just the right size and quantity to alter clouds. The Barrier Reef is a likely first candidate for tests.
Although regarded as one of the greatest natural wonders of the world — drawing two million visitors a year — two-thirds of the reef is already damaged and marine scientists fear the entire system has reached a critical point.
Dr Harrison and his team considered other ways of arresting the effects of climate change on the reef, including pumping cool water on to coral. However, they believe the cloud-altering technology is the most feasible and environmentally safe option.
“If we can make just a little bit less heat over the reef for a few months . . . when it’s at most risk of getting bleached [when coral begins to die], we should be able to cool the water a degree or two, which is enough to prevent most of the damage,” said Dr Harrison.
Higher sea water temperatures caused by global warming have been identified as the leading cause for coral bleaching worldwide. When water is too warm, corals will expel the algae living in their tissue, causing the coral to turn completely white. Corals can survive a bleaching, but they are under more stress and are subject to greater risk of mortality.
Bernard Lagan, Sydney
Large parts of the Great Barrier Reef will never fully recover from the bleaching of its coral,