Shading corals and deploying more heat-resistant species on the Great Barrier Reef on a scale not yet proven could buy the world heritage site another two decades, according to a study led by Australian government scientists.
The scientists said the combination of “life support” interventions such as cloud glow, which involves spraying seawater to make low-altitude clouds more reflective, with better management of a feeding starfish of corals could help delay the “precipitous falls” caused by global warming.
But the scientists said it would only be effective if firm global steps were taken to rapidly reduce greenhouse gas emissions.
The study, published in the journal Royal Society Open Science, it is presumed that new and mostly unproven technologies could be implemented on an unprecedented scale.
Coral reefs around the world are considered to be among the ecosystems most exposed to the climate crisis.
The lead author of the study, from Australia’s national scientific agency CSIRO, said the global warming results were “competing” but showed that there was a way to buy into the ecosystem at some point if technologies developed as expected.
“If the reef needs life support for a time, then these interventions are the way we could do it,” said Dr. Scott Condie, CSIRO senior principal research scientist.
“This is one way to keep the reef healthy until we can implement effective global action on climate change.”
Scientists in Australia are working on a $ 150 million government-backed program to develop and implement a variety of technologies and measures to protect the reef.
For the study, the scientists ran computer models with different combinations of approaches to see which one would keep coral cover at the highest levels.
Study co-author Dr. Ken Anthony, Associate Principal Research Scientist at the Australian Institute of Marine Sciences, said: “Corals are to reefs what trees are to forests. If you lose the frame, then you are saying goodbye to all the species that depend on them. “
Scientists from CSIRO, the Australian Institute of Marine Sciences, the University of Tasmania, the University of Queensland, Southern Cross University, the Great Barrier Reef Marine Park Authority and the University of Sydney contributed to the research.
The study assumed that the world would take strong action to reduce emissions, using a scenario in which global temperatures rise about 1.8 ° C from current levels.
Without any intervention, the models suggested that the average coral cover on each of the 3,753 individual reefs in the Great Barrier Reef would drop to just 3% by 2070.
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The combination of three approaches would provide the best result. The control of the coral-feeding Crown of Thorns starfish, the shade of reefs, and the development of more heat-tolerant corals saw a 53% increase in coral cover, compared to taking no additional action. .
The modeling results, the authors said, suggested that these gains delayed the “precipitous decline” in coral cover by about two decades.
Anthony said the set of approaches could be compared to a “health care strategy” to manage climate change, which was like a “systemic disease” for the reef.
“But he doesn’t give up on the patient. If you have comprehensive healthcare and make the best of new and existing interventions and scale them up, you can buy the reef at some point.
“The key message here is that there are no solutions without mitigation. There is a limit to how far we can go.”
Scientists widely recognize that climate change is the greatest threat to the reef’s future.
Ocean warming has triggered three major mass bleaching events since 2016. Bleaching weakens corals and can kill them if temperatures stay high. Excess heat can also kill corals completely.
The last bleaching event in 2020 that affected reefs along the 2,300-kilometer length was the most widespread on record.
Dr. David Wachenfeld, chief scientist for the Great Barrier Reef Marine Park Authority, described the event as an “urgent call for help.”
In 2019, the authority downgraded the reef’s long-term outlook to “very poor” for the first time.
In the research, the authors admit that the assumptions they used in their model about the effectiveness or scale of some of the interventions were optimistic.
One approach being developed is artificial structures placed around the base of reefs that help stabilize coral debris in which juvenile corals can grow. This could help on a more local scale.
But the model assumes that the deployment of these structures could be done at a scale of 100 hectares per year, which the authors say “is orders of magnitude larger than any previous deployment.”
Condie said that some of the assumptions about how quickly technologies could be developed and deployed were “aspirational” and others were possible “if you were prepared to invest enough.”
In another example, the model assumes that shading the reef through technologies such as cloud glow, which has been tested early, could reduce temperatures across the reef to the equivalent of 1 ° C for a month.
But the research says there remain “great uncertainties” in the “efficacy and profitability” of these technologies.
Professor Terry Hughes, director of the ARC Center of Excellence for Coral Reef Studies at James Cook University, which has been monitoring and investigating changes in the reef caused by global warming, said: says that interventions won’t help us there and we have to deal with the root causes: greenhouse gas emissions. “
Hughes said it seemed “unlikely” that reef shading could offer cooling at the levels modeled in the research.
“As the authors themselves say, they are modeling something that is orders of magnitude more than current interventions.
“I’m not saying I didn’t investigate this, but as the model shows, there is no reef-scale intervention that we could actually implement in a practical way that would make a difference.
“This is a blanket comment and not in relation to this document, but are we buying time for the reef or are we buying time for the fossil fuel industry so that its inevitable decline is simply postponed?
“A more rational approach should be to stop emissions.”
George is Digismak’s reported cum editor with 13 years of experience in Journalism