Abstract. The 2015/16 ENSO event severely raised the temperature of waters surrounding northeast Australia to above 30 ^oC, with large patches of water reaching 32 ^oC, for over two months, which lead to severe bleaching of coral reefs of the Northern Great Barrier Reef (NGBR). This study provides evidence through remote-sensing data and oceanographic modeling that three factors caused this excessive heating, namely: 1) the shutdown of the North Queensland Coastal Current, which would otherwise have flushed and cooled the Northern Coral Sea and also the NGBR through tidal flushing, 2) the advection of warm (> 30 ^oC) water from the Gulf of Carpentaria eastward through Torres Strait and then southward over the NGBR continental shelf, and 3) local solar heating. The eastward flux of this warm water through Torres Strait was driven by a through-strait mean sea level difference that in turn was controlled by the wind, and the wind also generated the southward advection of this warm water onto the NGBR shelf. On the NGBR shelf, the residence time of this warm water was larger inshore than offshore, and this may explain the observed cross-shelf gradient of coral bleaching intensity.

Biography. Professor Eric Wolanski is an estuarine/coastal oceanographer and an ecohydrologist at James Cook University, Australia. His research focuses on the interaction between physical and biological processes determining ecosystem health in estuaries, coastal wetlands, and coral reefs, and on the ecohydrology of African savannah ecosystems. He has 390 publications including the books “Physical oceanography processes of the Great Barrier Reef”,  “Oceanographic processes of coral reefs: Physical and biological links in the Great Barrier Reef”, “The environment in Asia Pacific harbours”, “Coastal Wetlands. An integrated ecosystem approach”, “Estuaries of Australia in 2050 and beyond”, and “Estuarine Ecohydrology. An Introduction”.  Eric is a Fellow of the Australian Academy of Technological Sciences and Engineering, the Institution of Engineers Australia (ret.), and l’Académie Royale des Sciences d’Outre-Mer (Belgium). He was awarded an Australian Centenary medal, two Doctorates Honoris Causa (the catholic University of Louvain and the University of Hull), and a Lifetime Achievement Award by ECSA.