For more than 20 years, NOAA Coral Reef Watch (CRW) has been using remote sensing, modeled, and in situ data to operate a decision support system to help resource managers, scientific researchers, decision makers, in-water monitoring networks, and other stakeholders around the world prepare for and respond to coral reef ecosystem stressors, predominantly resulting from climate change and warming of the Earth's oceans.

Offering the world's only global early-warning system of coral reef ecosystem environmental changes, NOAA CRW remotely monitors conditions that can cause coral bleaching, disease, and death; delivers information and early warnings in near real-time to our extensive and diverse user community; and uses operational climate forecasts to provide outlooks of stressful environmental conditions on coral reefs worldwide. CRW products are primarily sea surface temperature (SST)-based but also incorporate light and ocean color, among other variables.

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Coral reefs are one of the most biodiverse ecosystems in the world. They support essential coastal fisheries and local tourism, protect coasts from erosion and tropical storms, and are a source of potential pharmaceuticals. Sustained, high water temperatures, in conjunction with other natural and human-based stressors, may cause coral bleaching, including mass coral bleaching that spans tens, hundreds, or even thousands of kilometers, to become an annual event in most oceans. This could lead to a rapid decline in the health of coral reefs worldwide.

Corals are very sensitive to stress caused by elevated water temperatures, bright sunny days, and calm water. Corals respond to stressful temperatures by expelling the symbiotic algae that live within their tissues and provide most of their food and characteristic colors. While corals can recover from short-term, minor stress, they can starve and die if stressful conditions continue for weeks or months. Coral bleaching has become much more severe and frequent in recent decades as ocean temperatures have risen. For more information on coral bleaching, click here.

Click here for a brief history of the early years (1997-2007) of the NOAA CRW program. (Note that this is a PDF of the story that was originally featured on the "NOAA Celebrates 200 Years of Science, Service, and Stewardship" website. That archival website is currently offline and unavailable.)

While CRW sits within the National Environmental Satellite, Data, and Information Service (NESDIS) Center for Satellite Applications and Research (STAR), it is part of a larger effort that brings together expertise from across the NOAA Line Offices for a multidisciplinary approach to understanding and conserving coral reef ecosystems. For more information on NOAA's broader matrix of coral reef activities, please visit the Coral Reef Conservation Program (CRCP) website.