Scientists have said that the bleaching of the Great Barrier Reef is a result of a ‘perfect storm’ created by a number of factors acting in parallel.
According to scientists even when the temperatures shot up during the summer El Nino event, such as 1998, there have been no instances of coral bleaching in the Torres Strait and only small to moderate bleaching in the northern Great Barrier Reef. But in case of the summer of 2016, the bleaching has been extensive and this is because of a ‘perfect storm’ of factors.
A 2016 aerial survey of the northern Great Barrier Reef showed that 90 per cent of reefs in some of these areas were severely bleached.
Researchers reveal that satellite data showed the 2016 El Nino heating started in the Gulf of Carpentaria, with patches of water reaching an exceptionally high 34 degrees Celsius. The water then flowed east onto the Torres Strait reefs and south to the Great Barrier Reef. The ‘residence time’ of the very warm water in the Torres Strait and the Northern Great
Barrier Reef was exceptionally long, which increased the thermal stress on the coral.
All of these factors enabled local solar heating to proceed unrestricted. Examination of the surface currents reveal that the North Queensland Coastal Current in the Coral Sea, which would normally flush and cool the Northern Great Barrier Reef, actually did the opposite. It reversed course and brought very warm water to the Northern Great Barrier Reef. All these things together made it the perfect thermal storm, scientists say.
