NOAA’s Global Coral Bleaching Predictions

First four-month forecast issued; no bleaching seen in Northern Hemisphere through October

NOAA announced in July a major advance in the ability to predict mass coral bleaching – providing the probability of bleaching up to four months into the future – with a newly developed global seasonal outlook system.

Using the new seasonal ecological forecast system, unveiled at the International Coral Reef Symposium in Cairns, Australia, NOAA’s Coral Reef Watch does not anticipate any large scale coral bleaching events in the Northern Hemisphere through October 2012.

“This advance in bleaching warning systems represents another milestone in our efforts to save the world’s critically important reef systems,” said Jane Lubchenco, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator, in the symposium’s keynote address. “The state of reefs today should raise concerns for everyone. Reef ecosystems are globally important, and healthy reefs are the life-line for local communities. Their continued existence is a moral imperative for the global community.

“NOAA is firmly committed to bring new scientific efforts to change the current trajectory of loss of reefs and the services they provide,” she added.

Every week, the new system uses 28 runs of NOAA’s latest climate model to warn coral reef managers, scientists, stakeholders, and the public of large-scale bleaching events. It builds upon the first global seasonal bleaching outlook system, released by NOAA in 2008.

The new system uses sea surface temperature forecasts from NOAA’s operational climate forecast system, the same system used for predicting El Niño and seasonal temperature and precipitation forecasts. Coral bleaching occurs when stress, usually high temperature, causes corals to expel their symbiotic algae (zooxanthellae) and, if prolonged or particularly severe, may result in coral death.

NOAA has also significantly advanced near-real time satellite monitoring of the high ocean temperatures that can cause coral bleaching. A new generation version of NOAA’s product suite now provides daily 5-km satellite monitoring of coral bleaching thermal stress for reefs around the world. This represents 100 times finer resolution, more frequent observations, and more data than the current twice-weekly 50-km global satellite coral bleaching monitoring.

The new products use a blend of data from NOAA and international partner environmental satellites that orbit the globe with data from geostationary weather satellites, providing 10 to 50 times more observations each day than the old products. NOAA has been providing the current coral bleaching products to U.S. and international coral reef communities since 1997. These products have been very successful in detecting the thermal stress typically associated with mass coral bleaching.

During most mass bleachings, high ocean temperatures usually occur over a broad area that includes both coral reefs and adjacent open ocean waters. Since coastal water temperatures over reefs often are higher than those in other areas, NOAA’s old products often underestimated the thermal stress associated with a bleaching event or missed small-scale features found right over reefs. The new 5-km products should correct for this.

“Advances in coral reef management practices have driven the need for higher resolution monitoring and enhanced prediction of coral bleaching,” said C. Mark Eakin, Ph.D., coordinator of NOAA’s Coral Reef Watch program. “Higher resolution products, which is the improvement to Coral Reef Watch products most requested by scientists and resource managers, allow us to more accurately predict mass coral bleaching events, as well as more accurately account for episodes of minor or no coral bleaching.”

Map of coral bleaching alert system from NOAA.


Healthy coral reefs support commercial and subsistence fisheries as well as jobs and businesses through tourism and recreation. Local economies also receive billions of dollars from visitors to reefs through diving tours, recreational fishing trips, hotels, restaurants, and other businesses based near reef ecosystems.

NOAA’s Coral Reef Watch partnered with the NOAA National Centers for Environmental Prediction to develop the next-generation global seasonal bleaching outlook. Research and development of the high-resolution, 5-km coral bleaching thermal stress monitoring products has been a partnership between Coral Reef Watch, NOAA’s Center for Satellite Applications and Research, NASA, the University of South Florida, the United Nations Environmental Programme’s World Conservation Monitoring Centre, and the Cooperative Institute for Research in Environmental Science. Both new products were supported by funding from the NOAA Coral Reef Conservation Program and are now available on the Coral Reef Watch website.

NOAA’s mission is to understand and predict changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter and our other social media channels at http://www.noaa.gov/socialmedia/.

On the Web:
NOAA Coral Reef Watch: http://coralreefwatch.noaa.gov/satellite/index.html
NOAA Coral Program: http://coralreef.noaa.gov/