The Great Barrier Reef has seen its third mass bleaching (大规模白化) event in five years. For the first time, all three sections of the Australian reef have been badly affected. The damage happened in February when the area was exposed to the hottest month of water temperatures on record.
Surveys conducted by Terry Hughes at James Cook University in Australia and his team during March made it known that 25 percent of the reef had been badly bleached and 35 percent bleached to some degree. The northern, central and southern sections of the reef were all hit.
Terrible bleaching also struck in 1998, 2002, 2016 and 2017, but was limited to one or two sections. This is the first time that all three sections have experienced terrible bleaching at exactly the same time, says Hughes. "It's heartbreaking."
Some of the damaged corals (珊瑚) will survive, including more heat-resistant (耐热的) species. But many others were probably "literally cooked" at the peak of the heatwave in early 2020, says Hughes. Others will die more slowly from stress over the next few months, he adds. Hughes has serious concern about the southern reef, which was mostly unaffected in former bleaching events and hasn't developed the same heat resistance as other parts.
The 2016 and 2017 events killed about half the coral on the reef. It usually takes a decade for even fast-growing corals to recover, meaning the latest damage will seriously weaken the reef's ability to recover, says Hughes. The high frequency of mass bleaching in recent years has been driven by climate change, which results from human activity and is steadily raising ocean temperatures. The only way to deal with the problem is to immediately reduce the release of greenhouse gases, says Hughes.
