Ecology: Coral reefs could stop net growth by mid-21st century

Global coral reef ecosystems could dissolve faster than they grow by the middle of the century, according to a study published in Communications Earth & Environment. The findings, which identify factors that govern changes in global coral reef ecosystems, may help prevent coral reef deaths.

The survival of coral reefs depends on their ability to regenerate and grow by depositing calcium carbonate to make new reef structures, a process called calcification. Persistent, long-term declines in calcification rates have been observed in most coral reef regions worldwide, but understanding why growth rates are slowing and making robust, evidence based predictions about the future of coral reefs requires analysis of large amounts of data.

Kay Davis and colleagues analyzed 116 datasets obtained between 1971 and 2019 on coral reef ecosystems worldwide. They used a statistical model to identify trends of coral reef calcification and key drivers such as water depth, wave action and temperature. The authors found that calcification rates have declined by about 4% per year since the 1970s and that water depth and coral cover were the most important factors for driving calcification. The authors predict that this trend may lead to the balance between net growth and disintegration to shift so that coral reefs may become net dissolving in the 2050s. They conclude that this continuing trend in calcification decline is partly due to increasing global climate change stressors, such as ocean warming and coral bleaching events.