Coral bleaching in the Great Barrier Reef off the coast of Queensland, Australia
Nature Picture Library/Alamy
Researchers stress the urgent need for strategies to artificially provide shade from rising temperatures affecting Australia. This alerts us following recent findings that link changes in transport fuels to an increased risk of coral bleaching.
In recent years, significant sections of barrier reefs have experienced severe bleaching due to rising sea temperatures attributed to climate change.
Adjustments made in 2020 to regulations governing fuel composition have led to additional detriment, according to Robert Ryan from the University of Melbourne. These changes have decreased sulfur dioxide emissions, which are protective pollutants for health, but have also eliminated aerosols that contribute to the cooling of marine clouds over the reefs.
In February 2022, Ryan and his team leveraged computer models to analyze the impacts of cloud cover and solar radiation in relation to fuel emissions over a span of 10 days.
They discovered that emissions at the pre-2020 levels would enhance the local cooling effect of clouds and noted that regulations aimed at reducing sulfate aerosol pollution diminished this cooling effect. Consequently, the new transport fuel regulations led to a rise in sea surface temperatures equivalent to 0.25°C, which created coral bleaching conditions that ranged from 21-40% during the studied period.
“There’s been an 80% reduction in sulfate aerosol transport, likely contributing to conditions that favor coral bleaching in the Great Barrier Reef,” states Ryan.
Bjørn Samset from the International Climate Research Centre in Oslo, Norway, asserts that this study will help address critical inquiries regarding the effects of reduced aerosol pollution on the surrounding environment. “The local aerosol influences may be more significant than previously considered, and we still have limited understanding of their impacts on ocean heat waves,” he remarks.
However, he cautions that the findings illustrate evident links between air quality and the conditions of clouds around notable reef systems, though they only represent a brief timeframe and are complex compared to other related research.
Ryan is also involved in efforts to devise methods to artificially cool coral reefs using Marine Cloud Brightening (MCB), a climate intervention technology that involves dispersing ocean salt particles into the atmosphere to amplify the cooling effects of marine clouds.
Researchers suggest that given their recent findings, such artificial cooling measures for large barrier reefs may be more crucial than ever. “If changes in sulfate emissions have diminished the brightening effects of ocean clouds, it could be worth reconsidering their reimplementation in targeted programs,” Ryan explains.
Daniel Harrison from Southern Cross University in Australia emphasizes that their findings indicate that MCBs can effectively cool the reef, mirroring the cooling effects seen with past shipping emissions. “This study highlights the real-world implications of ongoing changes,” he adds. “It confirms that it was indeed effective.”
Harrison has secured funding from the UK’s Advanced Research and Innovation Agency for a five-year initiative to test the MCB in the Great Barrier Reef, asserting that MCB “aims to harmonize our efforts to lower emissions.”
On the other hand, some experts remain skeptical, arguing that there is insufficient evidence to confirm the safety and efficacy of intentional MCBs. Terry Hughes from James Cook University in Queensland, Australia, has stated that previous trials of MCB were “not successful” and produced no compelling evidence that it can reduce the local sea temperatures of the reef.
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Source: www.newscientist.com
