Climate change and coral bleaching: From satellite-derived nowcasts to model-derived forecasts

As a consequence of climate change, the frequency and intensity of mass coral bleaching has increased across the globe over the past decades. These events, which span across hundreds to thousands of kilometers, occur as a direct result of high temperatures. NOAA Coral Reef Watch has been providing operational satellite-based products to alert resource managers of the potential for coral bleaching since 2002. As these have continued to both see greater application in the research and management communities, NOAA has continued to develop and refine these products. However, these were inherently limited to short-term warnings and resource managers have been requesting products that provide longer lead-times. At the same time, the need for understanding the potential impact of future climate change has led to the need for decadal scale scenarios.

In July 2008, NOAA Coral Reef Watch launched a new seasonal prediction tool for coral bleaching conditions built from the methods and lessons from real-time satellite monitoring. The current model of thermal stress provides an outlook of the risk of coral bleaching two weeks to three months in the future was developed through collaboration with the Physical Sciences Division of the NOAA Earth System Research Laboratory. The current system is built on statistical sea surface temperature forecasts provided by NOAA's Linear Inverse Model (LIM) with new work starting to develop this system using ensemble forecasts from the dynamical NCEP Climate Forecast System and others. Future work may close the gap between these through the application of weather forecast models. At the same time the satellite-based system is serving as the basis for decadal scenarios using the GFDL Earth System Model.