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All the newsInnovation: cloud brightening to protect the Great Barrier Reef
The Great Barrier Reef continues to shrink. To halt this two-decade decline, large-scale interventions are needed according to a recent study published by the Royal Society. Could one of the solutions come from a prototype designed to cool coral and thus protect it from bleaching caused by higher temperatures? It is based on an original technology to brighten clouds.
The causes of bleaching
The coral cover of the emblematic Great Barrier Reef has been severely reduced by the cumulated effects of tropical cyclones, marine heat waves and regular epidemics of coral devouring starfish. Climate change risks further exacerbating this situation during the next decades if efficient measures are not implemented.
Coral reefs are considered to be the ecosystems most at risk. 2020 was marked by the third episode of massive coral bleaching in five years. Bleaching weakens the coral and can kill them, if temperatures remain high. According to the predictions of the United Nations Intergovernmental Panel on Climate Change (IPCC), between 70 and 90% of coral reefs will cease to exist if warming reaches +1.5°C. However, “corals are to reefs what trees are to forests. If you lose the frame, you can say goodbye to all the species that depend on it”, explained Ken Anthony, PhD and head researcher associated with the Australian Institute of Marine Science. If no action is taken, models predict that the average rate of coral cover on each of the 3,753 individual reefs of the Great Barrier Reef will fall to only 3% from now to 2070. In an unusual and ominous announcement made in 2019, the Australian government qualified the long-term outlook for the reef as being very poor.
An innovative technology
An original experiment was carried out to protect the coral. It uses a turbine with 100 high voltage nozzles that spray thousands of nanometric sea salt crystals in the air from the rear of a barge. This technique is aimed at mixing these tiny crystals with low altitude clouds, in order to brighten the latter and make them reflect more of the sun’s rays far from the surface of the water. The research team (Sydney Institute of Marine Science, University of Sydney and the Queensland University of Technology), in partnership with the Italian equipment supplier EmiControls, is continuing the tests to measure the system’s efficiency.
The experiment is part of 43 projects funded by the Australian government, which announced an envelope of Au$ 150 million at the beginning of April for research and development programmes to protect the reefs.
This innovation is raising many hopes in the scientific community thanks to its affordable cost and its ease of deployment. “Nature does most of the work for you,” said Dr Daniel Harrison project manager at the University of Southern Cross. “This makes hundreds of trillions of nano-sized salt crystals per second. They get into a cloud and grow a cloud droplet that reflects a lot more sunlight.”
The next steps will look into the possible impacts of this process on the marine habitat and local rainfall, on both sea and land. The researchers also want to strengthen the system with more powerful turbines to multiply the impact tenfold and act on larger aquatic surface areas.
However, this solution alone will not suffice, still less if the rise in temperatures is not contained. Action by reducing greenhouse gas emissions, the source of the harm, remains necessary.