Coral reefs may need more than carbon cuts

"In reality there is no direct choice between conventional mitigation and climate engineering, but this study shows that we need to either accept that the loss of a large percentage of the world's reefs is inevitable or start thinking beyond conventional mitigation of CO2 emissions," says Peter Cox. (Credit: "coral" via Shutterstock)

Climate geoengineering may be the only way to save coral reefs from destructive mass bleaching, according to new research.

Coral reef ecosystems are considered extremely vulnerable to future climate change, due to rising sea surface temperatures and ocean acidification caused by higher atmospheric levels of carbon dioxide.

University of Queensland Professor Peter Mumby says rising sea temperatures are a critical threat for coral reefs, and geoengineering could vastly reduce the problem.

The research finds devastating mass coral bleaching was likely to occur far more frequently in future, due to stress caused by higher seawater temperatures.

A geoengineering technique called Solar Radiation Management (SRM), which involves injecting gas into the stratosphere to form microscopic particles that reflect some of the sun’s energy, could help limit rising sea surface temperatures.

“We find that the benefits of SRM, over the standard CO2 reduction scenario, are dependent on the sensitivity of corals to changes in seawater acidity,” Mumby says. “Resolving this sensitivity remains a key priority for science.”

The study compared a hypothetical SRM geoengineering scenario to the most aggressive future CO2 reduction strategy considered by the Intergovernmental Panel on Climate Change (IPCC), and found that coral reefs fared much better under geoengineering, despite increasing ocean acidification.

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Professor Peter Cox of University of Exeter says coral reefs face a dire situation regardless of how intensively society decarbonized the economy.

“In reality there is no direct choice between conventional mitigation and climate engineering, but this study shows that we need to either accept that the loss of a large percentage of the world’s reefs is inevitable or start thinking beyond conventional mitigation of CO2 emissions,” says Cox.

The study appears in Nature Climate Change. The research also involved the Carnegie Institution for Science and the UK Hadley Centre.

Source: University of Queensland