The End Of All Coral Reefs?

Coral reefs from all around the world may die by the end of this century, say researchers. Accelerated carbon dioxide production is making the oceans more acidic, thus preventing the formation of a reef's basic skeleton.

Computer models designed by Dr. Ken Caldeira and Dr. Katharine Ricke, from the Carnegie Institution for Science in Washington, DC, USA, suggest that unless emissions are curtailed soon and carbon dioxide is somehow captured from air, oceans will become more acidic, and coral reefs will be unable to sustain themselves. Acidification affects the mineral aragonite, a form of calcium carbonate that corals use to make their skeletons. When carbon dioxide comes into contact and is absorbed by the ocean, carbonic acid is formed. This decreases the ocean's pH, and this acidity makes the creation of aragonite a much feat.

In their models, researchers included ocean conditions that occur under their three different scenarios. Specifically, they measured dissolved inorganic carbon, alkalinity (the opposite condition from acidity), sea surface temperature, and salt content. They then applied these models to water surround 6,000 coral reefs on the planet. The models showed that before the industrialization of the world began in the 19th century, nearly all reefs had plenty of available aragonite. Today, however, that situation is quickly reversing; already, scientists are reporting deadly bleaching of coral reefs.

"If we continue on our current emissions path, by the end of the century there will be no water left in the ocean with the chemical properties that have supported coral reef growth in the past," said Dr. Caldeira. "The decisions we make in the next years and decades are likely to determine whether or not coral reefs survive the rest of this century."

Dr. Caldeira and his colleagues are now collecting data at several reef sites worldwide to see if their computer models indeed match with actual tests of ocean water chemicals. For more information, check the official press release.