The world’s coral reefs are experiencing the fourth and largest global bleaching event in recorded history, according to the latest U.S. National Oceanic and Atmospheric Administration data.

The data explained that the bleaching-level heat stress had impacted 83.7 per cent of the world’s coral reef area between January 2023 and April 2025.

It said that the affected reefs spanned at least 83 countries and territories.

The agency called the current bleaching event “the biggest to date”, pointing out that the previous record was set during the third bleaching period, which lasted from 2014 to 2017.

“This was also when 68.2 per cent of the world’s reefs were affected,” it said.

Bleaching occurs when rising ocean temperatures expel the algae living within coral tissues.

However, corals would have had the potential to recover if the environmental stress had been reduced.

According to the agency, the first and second global coral bleaching events occurred in 1998 and 2010, respectively. 

(Xinhua/NAN)