In dozens of regions

Coral bleaching continues to expand worldwide

Ein infolge hoher Wassertemperaturen gebleichtes Korallenriff

(Bild: APA/AFP/WWF Australia)

According to US experts, the coral bleaching that has been ongoing for months in many regions of the world has once again increased significantly. The phenomenon, which is life-threatening for corals, has now been detected in 62 countries and territories, the US National Oceanic and Atmospheric Administration (NOAA) announced on Thursday (local time).

This is nine states and territories more than in the previous NOAA warning issued in mid-April. The new areas with coral bleaching detected since then include India and Sri Lanka. The phenomenon caused by high ocean temperatures "continues to increase in scope and impact," said NOAA coral reef monitoring expert Derek Manzello. He made a direct link to the rise in global temperatures: "This would not be happening without climate change."

Reef on the vacation island of Phuket closed
Reefs in both the northern and southern hemispheres are affected by bleaching. The current massive coral bleaching is occurring on the Great Barrier Reef in Australia and in Thailand, among other places. In Thailand, Pling Island and the reef around the Sirinart National Park on the vacation island of Phuket were closed to visitors last week due to coral bleaching.

According to NOAA data, 60.5 percent of the world's coral reefs have suffered from sea temperatures that trigger bleaching in the past twelve months. When the water is too warm, the corals reject the algae living in them, which are their primary source of food. As a result, the corals lose their color and become endangered.

Fourth bleaching event since records began
NOAA's heat stress monitoring of corals has been based on satellite measurements since 1985. The current massive global coral bleaching event is the fourth since records began - the phenomenon previously occurred three times between 1998 and 2017.

The previous global coral bleaching event between 2014 and 2017 remains the most devastating to date, according to Manzello. However, he warned that the current coral bleaching could spread to reefs in the Caribbean and off the coast of the US state of Florida as a result of further warming of the oceans in summer.

Will 2024 be the hottest year on record?
According to NOAA expert Karin Gleason, there is a 61 percent probability that the current year will be the hottest year worldwide since records began. It is already 100 percent certain that it will be one of the five hottest years on record. So far, 2023 holds the record as the hottest year.

Among the oceans, the Atlantic is particularly affected by the high temperatures of the current year, Manzello explained. However, he hopes that the cooling weather phenomenon La Niña will come to the corals' aid in the coming months. The percentage of reef areas affected by bleaching could then "start to decrease", said the NOAA expert.