"Coral reef ecosystems are going to be significantly impacted by climate change," Kleypas says. "They're already being degraded by both climate change and by direct impacts such as overfishing and habitat loss, and the combination of these stresses can be devastating."
The Pew report notes that coral reefs are among the most biologically diverse ecosystems on Earth, providing vital habitat to numerous species as well as economic benefits to society in the form of fishing and tourism. One recent estimate concluded the world's reefs provide annual net economic benefits of $30 billion. But more than 10% of the reefs have been destroyed by human activity, and an additional 16% were extensively damaged in 199798 alone by coral bleaching during a major El Nio event.
Kleypas emphasizes that it is impossible to predict the future of reefs with any precision because, in the millions of years that modern coral reefs have flourished, the atmosphere has rarely, if ever, contained the high levels of carbon dioxide that are expected to accumulate in coming decades. However, recent losses in reefs show that human-related impacts are exceeding the adaptive ability of coral reef organisms. The severity of what has come to be known as the "coral reef crisis" is expected to worsen with future climate changes.
"We're really outside of any normal envelope that coral reefs have existed in," Kleypas says. "We haven't had carbon dioxide levels this high for thousands of years, maybe millions of years, and given the sensitivity of coral reefs to high temperature and ocean acidity, we c
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13-Feb-2004