Coral reefs suffer fourth global bleaching event, says NOAA

PARIS: Along coastlines from Australia to Kenya to Mexico, many of the world’s colourful coral reefs have turned a ghostly white in what scientists said on Monday amounted to the fourth global bleaching event in the last three decades.

At least 54 countries and territories have experienced mass bleaching among their reefs since February 2023 as climate change warms the ocean’s surface waters, according to the US National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch, the world’s top coral reef monitoring body. Bleaching is triggered by water temperature anomalies that cause corals to expel the colorful algae living in their tissues. Without the algae’s help in delivering nutrients to the corals, the corals cannot survive.

“More than 54 perccent of the reef areas in the global ocean are experiencing bleaching-level heat stress,” Coral Reef Watch coordinator Derek Manzello said.Announcement of the latest global bleaching event was made jointly by NOAA and the International Coral Reef Initiative (ICRI), a global intergovernmental conservation partnership. For an event to be deemed global, significant bleaching must occur in all three ocean basins - the Atlanti.Like this year’s bleaching event, the last three - in 1998, 2010 and 2014-2017 - also coincided with an El Nino climate pattern, which typically ushers in warmer sea temperatures.