Abstract
Thermal coral bleaching events (CBEs) over the Pacific, including those
over the Great Barrier Reef (GBR), have commonly been linked to the El
Niño–Southern Oscillation (ENSO), with bleaching reported to be a
direct result of sea surface temperature (SST) anomalies driven by El
Niño. However, such a relationship cannot explain CBEs that occurred
during La Niña or the neutral phase of the ENSO. Here we show that the
GBR is characterized by a significant negative correlation between total
cloud cover anomaly (TCCA) and lagged SST anomaly (SSTA) whose magnitude
and spatial extent are greater than the SSTA-ENSO correlation. This
significant negative TCCA-SSTA (lagged) correlation prevails over
two-thirds of the study domain even after the ENSO signal is removed,
which suggests that local-scale reduced cloud cover is a key component
of the regional warm shallow water formation over the GBR and the
occurrence of thermal CBEs.