The coral reefs of the world, on which the news focus section of this issue of Science concentrates, are important for all sorts of reasons. For many, exploration by diving provides a unique connection with a fascinating natural ecosystem. For scientists, including climate scientists, the health of reefs provides insight into the physical and biological welfare of the oceans as a whole. And for conservation biologists, shallow-water reefs are remarkable hot spots of biodiversity; those that surround oceanic islands often include a level of specialized endemic species that rivals that on the islands themselves. But the corals of the world are in trouble, and that’s why we need the International Year of the Reef (IYOR) in 2008.
There are two problems, both of them serious. The addition of carbon dioxide and other greenhouse gases to the atmosphere has altered both the ocean’s temperature and its acidity. Because most shallow-water corals exist near their temperature optimum, some are becoming heat-bleached. The more problematic concomitant of climate change is that when carbon dioxide is absorbed by the oceans, as 30% of global industrial production is, it forms bicarbonate and hydrogen ions, which lower ocean pH and threaten the carbonate structure of the reef with dissolution. Since the industrial revolution, average ocean pH has been reduced by about 0.1 unit, and models predict further loss of 0.3 or 0.4 unit by the end of the century. Thomas Lovejoy, president of the H. John Heinz III Center for Science, Economics, and the Environment, calls it “the single most profound environmental change I’ve learned about in my entire career.” In Australia, which has the best-managed reefs in the world, the Institute of Marine Science conducts continuous monitoring to document these changes.
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