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2,600 scientists: climate change killing the world’s coral reefs

Purple coral off the coast of Maui, Hawaii. Photo by: Rhett A. Butler.
Purple coral off the coast of Maui, Hawaii. Photo by: Rhett A. Butler.

In an unprecedented show of concern, 2,600 (and rising) of the world’s top marine scientists have released a Consensus Statement on Climate Change and Coral Reefs that raises alarm bells about the state of the world’s reefs as they are pummeled by rising temperatures and ocean acidification, both caused by greenhouse gas emissions. The statement was released at the 12th International Coral Reef Symposium.

“Rising sea levels, more intense storms, changes in ocean chemistry due to air and water pollution—all these stress coral reefs,” said chief organizer of the statement, Steve Palumbi with the Center for Ocean Solutions, in a press release. “At least 25 percent of the world’s coral reefs have been degraded. Because of the global origin of climate change, the only way to tackle this is through a worldwide effort.”

Higher temperatures in the ocean has resulted in unheard of coral bleaching events, whereby the coral loses its symbiotic zooxanthellae, which can severely weaken reefs and even lead to mass mortality. In addition, acidification of the oceans, which is caused by excessive carbon inputs into the ocean, decreases calcium carbonate; corals, as well as marine mollusks and even some plankton, depend on calcium carbonate to survive. A recent study found that ocean acidification is currently occurring at a rate not seen for 300 million years, a trend that could eventually lead not only to coral decline, but mass extinction throughout the oceans.

“The international Coral Reef Science Community calls on all governments to ensure the future of coral reefs, through global action to reduce the emissions of carbon dioxide and other greenhouse gases, and via improved local protection of coral reefs,” the statement reads. While governments have been negotiating climate change agreements for decades, global greenhouse gas emissions continue to rise. A lack of concerted action means that global temperatures are currently on track to hit 6 degrees Celsius (11 degrees Fahrenheit) by 2100, according to the International Energy Agency (IEA); this would essentially lead to a climate catastrophe with temperatures rising higher than they have been in 50 million years.

Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies, echoed warnings by the IEA: “There is a window of opportunity for the world to act on climate change—but it is closing rapidly.”

The statement also makes note that coral reefs are being injured by other human impacts in addition to climate change, such as overfishing, habitat destruction, and pollution.

“The world, its coral reefs and the millions of people that depend upon them need more bold action,” the head of the U.S. National Oceanic and Atmospheric Administration, Jane Lubchenco, speaking at the conference told attendees:

In uncharacteristically strong words about climate change from the Obama Administration, Lubchenco noted that within 50 years 95 percent of the world’s coral reefs could suffer bleaching events. In addition, ocean acidification—which she called “climate change’s equally evil twin”—posed a “a serious threat to most corals.”

Researchers have estimated that coral reefs provide ecosystem services worldwide to the tune of $170 to $375 billion. Many communities depend on coral reefs for food security, storm and erosion buffers, and tourism. They are also the ocean’s most biodiverse ecosystem, harboring around a quarter of the world’s marine species.

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