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Coral will dissolve if CO2 emissions don’t change

Coral reefs under the business-as-usual-emission scenario, will quickly decalcify and dissolve. prilfish

The world’s coral reefs will quickly dissolve if greenhouse gas emissions continue on current trends, a new simulation has found.

Greenhouse gases cause the ocean to become warmer and more acidic, which bleaches and kills coral reefs, as well as the underwater ecosystems that form around them.

The new study, led by researchers from the University of Queensland and published in the journal PNAS, found that even modest increases in ocean temperature and acidity would kill off coral and increase the dissolution of their skeletons once they are dead.

“We discovered that coral reefs under the business-as-usual-emission scenario, the one we are on, show high rates of decalcification,” said lead author of the study, Associate Professor Sophie Dove from UQ’s School of Biological Sciences.

“Essentially, dissolving before our eyes over a few months.”

The study involved controlling the temperature and amount of CO2 in water that was home to a section of coral reef at UQ’s Heron Island research centre.

Study co-author Professor Ove Hoegh-Guldberg, director the University of Queensland’s Global Change Institute, said the study showed “that coral reefs are under even greater threat from ocean warming and acidification than we first thought.”

“This sounds gloomy but our study also emphasises the fact that there is time and that a small amount of effort today can have a huge impact on what happens in the future,” he said.

Zoe Richards, Coral Biodiversity Researcher at the Western Australian Museum, said the new study was ambitious and allowed researchers to study coral reefs in systems that more closely replicate the natural environment.

“The results suggest that in comparison to pre-industrial levels, reef calcification rates are already compromised by the current level of atmospheric CO2. Under optimistic future emission scenarios (to 2050), the ability for reefs to continue to grow and recover from natural events such as cyclones is severely jeopardised,” said Dr Richards, who was not involved in the study.

“Under worst-case emission scenarios, reef dissolution appears inevitable and other unforeseen changes such as increases in microbial biomass are anticipated.”

Dr Richards said that the new study “demonstrates in an unprecedented way that the benefits of acting upon climate change are tangible and real for complex, dynamic and sensitive coral reef ecosystems.”

“If our goal as a global community is to protect, or at the very least, maintain the potential for coral reefs to grow, and ultimately, sustain the benefits they provide to humanity - there is no choice other than to curb CO2 emission levels,” she said.

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