The sea surface temperature (SST) model forecast (NOAA) for the Great Barrier Reef (GBR) is predicting widespread bleaching, with severe scenarios predicted to affect the northern GBR from mid January 2009. Predictions for the month of December suggests that the potential for bleaching from central GBR intensifying to the north will extend into 2009.  When sea surface temperature forecasts exceed bleaching thresholds and continue long enough to cause bleaching, the outlook products display the bleaching potential during the upcoming warm season.

The NOAA Coral Reef Watch Bleaching Thermal Stress Outlook indicates that the greatest chance of bleaching during the upcoming austral summer will be in the region bounded by Papua New Guinea, the Solomon Islands, and the northern Great Barrier Reef (GBR). The figure above shows the most recent global 17-week Coral Bleaching Thermal Stress Outlook from the 09 December 2008 model run.

Actual conditions for December show temperatures around the central GBR 0.75-1.0 degrees Celsius above the MMM +1 (mean monthly maxima), and above 1 degrees Celcius to the Northern GBR and waters SE of PNG (Link). Recent SST changes have also been mapped by the Australian Bureau for Meteorology and confirm gradual warming on the GBR despite sub surface cooling in the central to eastern pacific.

Current SST tracking on Heron island on the southern GBR shows temperatures following a similar profile to that of the 2001/2002 bleaching event. The increase in SST over the next month will be critical in determining the risk of bleaching across southern GBR.

The majority of dynamic computer models are predicting neutral climate conditions to continue through the southern summer, however, some models are predicting a return to La Niña conditions which may drive monsoon, storm like conditions and generate some cooling in Queensland (Link). More updates as they come.