An aerial survey of the Great Barrier Reef shows coral bleaching is sweeping across the area off the east of Australia for the third time in five years. Bleaching has struck all three regions of the world’s largest coral reef system and is more widespread than ever, scientists from James Cook University in Queensland said Tuesday, per the AP. The air surveys of 1,036 reefs in the past two weeks found bleached coral in the northern, central, and southern areas. "As summers grow hotter and hotter, we no longer need an El Nino event to trigger mass bleaching at the scale of the Great Barrier Reef," says professor Terry Hughes. "Of the five events we have seen so far, only 1998 and 2016 occurred during El Nino conditions." The Great Barrier Reef, made up of 2,900 separate reefs and 900 islands, is unable to recover because there is not enough time between bleaching events.
"We have already seen the first example of back-to-back bleaching—in the consecutive summers of 2016 and 2017," which proved most deadly, Hughes said, adding that the number of reefs spared from bleaching is shrinking as the problem becomes more widespread. He said underwater surveys will be carried out later in the year to assess the extent of damage. In early March, the chief scientist at the Great Barrier Reef Marine Park Authority said the reef was facing a critical period of heat stress over the coming weeks following the most widespread coral bleaching the natural wonder has ever endured. The government agency that manages the coral expanse off northeast Australia said ocean temperatures over the next month would be crucial to how the reef recovers from heat-induced bleaching. They were 3.6 to 5.4 degrees above the March average in parts of the marine park. (Read more Great Barrier Reef stories.)