84% of coral reefs are bleaching, and it’s still ongoing

According to scientists, the most intense global coral bleaching event on record is still ongoing. One year after the International Coral Reef Initiative (ICRI) officially declared the fourth global coral bleaching event, bleaching alerts continue to develop worldwide. 

From 1 January 2023 to 30 March 2025, bleaching-level heat stress impacted 84% of the world’s reefs, with 82 countries, territories and economies suffering damage. During the first global coral bleaching event in 1998, 21% of reefs experienced bleaching-level heat stress, rising to 37% in the second event in 2010 and 68% during the third event (2014-2017)1.

Scientists called the fourth global coral bleaching event “unprecedented” as early as May 2024, and a widely used bleaching prediction platform had to add three new levels (Levels 3-5) to their Bleaching Alert Scale to indicate the heightened risk of mass coral mortality. The previous highest level, Level 2, indicates risk of mortality to heat-sensitive corals; Level 5 indicates the risk of over 80% of all corals on a reef dying due to prolonged bleaching.

• Read the full story at GCRNM

Main image credit Vardhan Patankar, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons