“If we want coral reefs by 2050, we have to do something about carbon dioxide”

So says Nancy Knowlton, chair of Marine Sciences at the Smithsonian, in an article for the Guardian by Suzanne Goldenberg. A new report from the World Resources Institute “Reefs at Risk Revisited” suggests that three-quarters of the world’s coral reefs are at risk from overfishing, pollution and climate change.

The report serves as an update to the 1998 publication “Reefs at Risk”- the first global, quantitative assessment of threats to coral reefs ever conducted. Since this initial report, the threat posed to reefs worldwide from climate change has grown. Reefs are threatened by a combination of local pressures – such as overfishing, particularly in the Indian and Pacific Oceans where aggressive dynamite fishing has left reefs in a parlous state – and global stressors. An increase in the concentration of carbon dioxide in the atmosphere, and therefore in the sea, is leading to ocean acidification which prevents corals from laying down their calcium-rich exoskeletons, and increases in temperature which are killing the photosynthetic unicellular algae (‘zooxanthellae’) which make it possible for coral to survive. Such coral ‘bleaching’ is becoming more widespread.

If climate change is not addressed, virtually all of the world’s coral reefs will be in danger by 2050. However the report gives reasons for optimism, suggesting in particular that Marine Protected Areas can prove a useful tool in coral conservation. Dr Mark Spalding, Nature Conservancy, based in Cambridge, UK, says that “Well managed marine protected areas are one of the best tools to safeguard reefs…At their core, reefs are about people as well as nature: ensuring stable food supplies, promoting recovery from coral bleaching, and acting as a magnet for tourist dollars. We need to apply the knowledge we have to shore up existing protected areas, as well as to designate new sites where threats are highest, such as the populous hearts of the Caribbean, Southeast Asia, East Africa and the Middle East”.

The report provides additional information to policy-makers, business leaders, ocean managers, and others which can aid them in developing means to better manage coral reefs and to ensure that the threats they face are adequately tackled. Speaking at the launch of the report in the U.S., Dr Jane Lubchenco, of the National Oceanic and Atmospheric Adminstration (NOAA), and under secretary of commerce for oceans and atmosphere under President Barack Obama, commented that “It will take a Herculean effort to reverse the current trajectory and leave a healthy ecosystem to our children and grandchildren”.