The situation of the world’s coral reefs is dramatic. “Saving coral reefs requires immediate and drastic reductions in global CO2 emissions,” says Professor Morgan Pratchett of the ARC Center of Excellence for Coral Reef Studies (Coral CoE) at James Cook University (JCU). In a recent study, the CoE examined net calcification, bioerosion and sediment dissolution rates measured or compiled at 233 sites on 183 different reefs. Forty-nine percent of the reefs were in the Atlantic Ocean, 39 percent in the Indian Ocean and 11 percent in the Pacific Ocean. The study produced three scenarios with minor, moderate and major impacts on ocean warming and acidification and their interaction – on the net carbonate production of coral reefs for the years 2050 and 2100.
The joint lead authors alongside Professor Pratchett, Dr. Christopher Cornwall of Victoria University of Wellington and Dr. Steeve Comeau of Victoria University of Wellington show in their projections that reefs will suffer greatly reduced growth or growth rates even in the case of low impacts. “While 63 percent of reefs will continue to grow by 2100 under the low impact scenario, 94 percent will erode by 2050 under the worst case scenario,” Dr. Cornwall said. “And no reef will continue to grow at rates equal to projected sea level rise under the medium and high impact scenarios by 2100.”
Pratchett said the results show that coral reef growth will be inhibited unless carbon dioxide emissions are drastically reduced. “The threat to coral reefs from climate change is already very evident due to recurring episodes of mass coral bleaching,” he said. But changing environmental conditions will have other far-reaching consequences.” This will have severe impacts on reefs, reef islands, and the people and other organisms that depend on coral reefs.