April 2, 1999
One of the article's authors is Robert Buddemeier, senior scientist at the Kansas Geological Survey, based at the University of Kansas.
Other authors are from the National Center for Atmospheric Research in Boulder, the University of Chicago, Lamont-Doherty Earth Observatory in New York, the Australian National University and the Observatoire Oceanologique in France.
Carbon dioxide is one of the gases commonly produced during the burning of fossil fuels and its increase in the atmosphere has been associated with climate change.
Buddemeier and his co-authors say that increased carbon dioxide in the atmosphere dissolves in seawater and changes ocean chemistry. Reef-building animals such as corals take minerals out of seawater and use the minerals to build skeletons, creating reefs. A change in ocean chemistry, however, may mean that these animals secrete less calcium carbonate, resulting in reduced reef-building and increased erosion of existing reefs.
The authors studied changes in near-surface water chemistry using two models. Both models show changing ocean-water chemistry through the middle of the 21st century. The authors say that the rate of production of certain reef-building minerals, such as aragonite and high-magnesium calcite, may have already decreased by an average of 6 to 11 percent in some areas, and could decrease by as much as 17 to 35 percent by the year 2100.
"A decrease in calcium carbonate production by 10 to 20 percent will pose a significant problem for many coral reefs," said Buddemeier. "Certain reefs, such as those in Bermuda or Florida, or reefs that are already experiencing stress from human activities, may be most vulnerable."
The researchers point out that they are not predicting the demise of the world's reefs. But they do believe that increased carbon dioxide concentrations may make it more difficult for reefs to withstand erosion, for example, much the way that osteoporosis can weaken bones in humans and make them more susceptible to breaking.
Scientists are particularly interested in reefs because of the diversity of ocean species they harbor.
"Our results are the first clear indication of carbon dioxide harming a major ecosystem," said Buddemeier. "This is occurring as the result of a global, chemical alteration of the environment, and the effect will be in addition to any problems resulting from climate change."
Because of the impact of decreased reef construction on ocean ecosystems, the authors suggest that additional research is warranted, particularly into the chemistry of shallow water, the reef-building physiology of corals and algae, and in the geologic record of reef building. Many Kansas limestones, for example, were deposited in shallow ocean water and can be studied to help scientists understand reef building during the geologic past.
Science is a weekly technical journal of the American Association for the Advancement of Science and is among the most respected of the nation's scientific publications. The work was funded, in part, by the Scientific Committee on Oceanic Research, the International Geosphere-Biosphere Program, and National Oceanic and Atmospheric Administration.