Researchers and innovators are piling on to the effort to geoengineer a way to protect Australia’s Great Barrier Reef from a warming ocean. But as intriguing as some of the solutions are, critics say such projects do nothing but put a very expensive, potentially destructive band-aid on a problem that will only be solved by sharp emissions cuts.
During the devastating heat wave of early 2020, sea temperatures around the Great Barrier Reef rose above 29°C, “causing more than a quarter of the corals on the reef to turn a ghostly white,” writes  Hakai Magazine.
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“It was the third mass coral bleaching  event to hit the UNESCO World Heritage Site in just five years,” the publication adds.
Responding to this tragic and escalating pattern, the climate-denying government of Prime Minister Scott Morrison launched a two-year, A$4.6-million feasibility study on methods to heat-proof the reef. Among the 160 interventions investigated was a plan to use a network of pipes to douse overheating coral reefs with cooler sea water.
To test the viability of cool water injection, aquatic scientists from the government’s Commonwealth Scientific and Industrial Research Organisation used computer models to recreate the mass bleaching event that occurred at 19 sites along the Great Barrier Reef five years ago.
Analyzing tidal pattern and currents, the researchers were able to determine which parts of the reef would have been most likely to retain the injected water long enough to for it to have an effect.
They also estimated that “pumping water cooled to 27°C—1°C cooler than the average temperature on the reef—through four pipes at a rate of five cubic metres per second could cool 97 hectares of reef by at least 0.15°C, which would be enough to ward off record-breaking sea temperatures and prevent bleaching.”
But such salvation would require “gargantuan” amounts of energy. Hakai writes that keeping just one of the region’s 3,100 reefs cool through the summer heat “would cost around US$3.9 million in energy alone.”
With 79% of Australia’s energy currently derived from fossil fuels, the bitter ironies of the process are clear, adds Hakai.
But efforts to geoengineer safety for the Great Barrier Reef continue, with the federal government recently investing a further $116 million to test and develop the 43 “most promising interventions  identified by the initial two-year study.” These include “spraying tiny saltwater droplets into clouds to reflect sunlight, repairing damaged parts of the reef with 3D-printed structures, and creating nano-sized water bubbles to shade vulnerable corals.”
But some ocean scientists are giving these ideas a thumbs-down. “The first step in any restoration project should always be to remove the causes of environmental decline—otherwise, history will repeat itself,” said Terry Hughes, director of the Australian Research Council Centre of Excellence for Coral Reef Studies.
“Governments and many industries often want to be seen to be doing something to allay public concern over the decline of reefs, even if their support for restoration projects is a smokescreen for inaction on climate change,” he told Hakai.