What can happen is that coral reefs can die out in one location, and re-establish themselves somewhere else. They are sensitive to water depth, and scientists have found fossil remains of reefs that have "drowned" and some that were left high and dry.

Coral-generating species have changed over time, but one of the most common ones today has been around since the Permian-Triassic extinction event that killed over 90 percent of all marine species, including invertebrates.

Other things that affect coral reef health include changes in water temperature, natural predatory cycles, sea levels, and even dust from storms in Africa.

There are also man-made influences like run-off pollution, and in particular, physical damage from bad fishing practices. Local reefs are very important to the nations that possess them, and conservation practices to protect them, including putting them on preserves, are essential to keep the reefs a healthy fish-spawning and tourist resource. Reefs that have been so protected are doing pretty well.

The status of coral reefs (among other environments) is a serious and complicated subject, and doesn't need hyperbole any more than any other environmental subject does. Note that as with many other research projects on environmental issues, serious and detailed study of this issue began only within my own lifetime, while reef changes can often take decades or hundreds of years.

But again, the idea that environmental changes will render reefs extinct is ridiculous.