Support Our Work
A look at weather extremes and the big-picture climate connections.

Risks Keep Rising for Coral Reefs, Analysis Finds

Every year, coral reefs off the coast of Florida draw millions of tourists to their vivid undersea colonies of corals, crustaceans, and fish. But rising water temperatures and carbon dioxide-induced ocean acidification, combined with overfishing and pollution, are threatening the survival of these reef ecosystems, scientists say. With more than 90 percent of the species living in Atlantic reefs not found anywhere else in the world, many animals and corals could be lost entirely in the coming years. And if the reefs are lost, or just significantly damaged, the Floridian communities that depend on reef tourism could suffer dramatic economic consequences, standing to lose over $1 billion.   


Many of the coral reefs in the Atlantic and Caribbean are threatened by local activities and global climate change. Credit: WRI

According to a new report from the World Resources Institute (WRI), Reefs at Risk Revisited, more than 75 percent of the coral reefs in the Atlantic, including those surrounding Florida, are now threatened by human activities. Though overfishing is the largest single threat to coral reef ecosystems in the area, marine species are becoming more vulnerable to the effects of climate change and high carbon dioxide (CO2) emissions, says the report. 

This morning, NOAA administrator Jane Lubchenco helped launch the new report, which details the current status of the world’s reefs. The analysis draws on a decade of research from over 25 international organizations, and is an updated version of a similar assessment made in 1998.

“This is a critical time for ocean ecosystems in general, but in particular for coral reefs,” said Lubchenco, speaking at the National Press Club in Washington, DC. Since the initial Reefs at Risk report, she described the threats to coral reefs as having gone from “worrisome to dire.”

Through a series of maps, the Reefs at Risk project illustrates which reefs are the most vulnerable to the harsh effects of overfishing, pollution and climate change (both warming sea surface temperatures and ocean acidification). Reefs everywhere are affected by fishing, coastal development and pollution, but to very different degrees. Yet the global impacts of climate change, says the report, are having a distinct impact on all reefs. It’s mostly a bad news story, as the report finds that:

·      More than 75 percent of the world’s reefs are at risk of being severely damaged or lost entirely.

·      By 2030, about half of the world’s reefs will experience enough heat stress from warming oceans that they could suffer severe bleaching in most years.

·      By 2050, more than 95 percent of global reefs are likely to experience bleaching each year.

Increasing ocean temperatures are expected to cause more coral bleaching events in the next 50 years. Credit: WRI  

Although corals can often recover from episodes of bleaching, researchers are not sure how coral colonies will tolerate repeated bleaching events, especially if they are simultaneously living in a more acidic environment than they are today. As the report says:

Rising levels of CO2 in the oceans are altering ocean chemistry and increasing the acidity of ocean water, reducing the saturation level of aragonite, a compound corals need to build their skeletons. By 2030, fewer than half the world’s reefs are projected to be in areas where aragonite levels are ideal for coral growth, suggesting that coral growth rates could be dramatically reduced. By 2050, only about 15 percent of reefs will be in areas where aragonite levels are adequate for coral growth.

Disclosure: Dr. Jane Lubchenco was a founding board member of Climate Central.

« Extreme Planet