We won't hear much of this because of other world events, but it is happening again
One quarter of the Great Barrier Reef suffered severe bleaching this summer in the most widespread outbreak ever witnessed, according to analysis of aerial surveys of more than 1,000 individual reefs released on Tuesday.
Prof Terry Hughes, director of the Centre of Excellence for Coral Reef Studies at James Cook University, surveyed 1,036 reefs from a plane over nine days in late March. The marine park authority also had an observer on the flights.
Hughes has released maps showing severe levels of bleaching occurred in 2020 in all three sections of the reef – northern, central and southern – the first time this has happened since mass bleaching was first seen in 1998.
Some 25% of the reefs were severely bleached – meaning that more than 60% of the corals on each reef had bleached.
Hughes said previous observations had shown that
bleaching at that extent leads to “high levels of mortality” of corals.The Great Barrier Reef has experienced five mass bleaching events – 1998, 2002, 2016, 2017 and 2020 – all caused by rising ocean temperatures driven by global heating.Hughes said there probably would not be the same level of coral death in the north and central regions in 2020 as in previous years, but this was partly because previous bleaching outbreaks had killed off the less heat-tolerant species.
The 2020 bleaching was second only to 2016 for severity, Hughes said.
https://www.theguardian.com/environment/2020/apr/07/great-barrier-reefs-third-ma...