Continually dumping crushed rocks from a bulk carrier along a Great Barrier Reef shipping route could counteract the acidification of ocean water caused by fossil fuel burning, but would come with unknown side effects on the marine environment and coral reefs, according to a study from Australia’s science agency, the Commonwealth Scientific and Industrial Research Organization (CSIRO).
In what is described as a “first order assessment,” scientists at CSIRO found it was theoretically possible to turn back the clock on the effect of decades of fossil fuel burning, but the radical step came with “as yet unquantified risks.”
As well as causing the atmosphere and oceans to warm, increasing levels of carbon dioxide in the atmosphere from fossil fuel burning has changed the pH of the ocean, making it harder for corals to form their skeletons—a process known as calcification.
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One reef expert, prof Terry Hughes of James Cook University in Queensland, described the concept of adding materials to the Great Barrier Reef’s waters—as modelled in the study—as “reckless.”
Reef scientists are exploring the viability a range of local interventions to try and buy time for the world’s largest coral reef system. A trial has already been carried out of a delivery system to spray trillions of nano-sized ocean salt crystals to brighten clouds, that could be deployed to cool the reef during summer periods when corals are at risk of bleaching.
The new study, published in the journal Environmental Research Letters, raises the concept of using an existing shipping route to deploy an alkaline material that could raise the pH level of the water, making it less acidic. The research used actual pH measurements taken from sensors on a ship owned by mining company Rio Tinto that travels the Weipa to Gladstone route—a journey that typically takes four days.
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The model suggests a continuous release of the material every three days for one year along the reef’s length offsets four years of ocean acidification caused by current carbon dioxide emissions.
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Scientists have already carried out a small-scale experiment on a coral cay on the southern part of the Great Barrier Reef, showing that adding an alkaline solution to the water increased the rate at which corals could build skeletons.
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Editor’s note: This story was originally published by The Guardian. It appears here as part of the Climate Desk collaboration.
Graham Readfearn, Bulletin of the Atomic Scientist, 4 August 2021. Press release.
