More than 80% of world's coral reefs hit by worst bleaching event in history

Source: The Independent

Wednesday 23 April 2025 04:50 EDT


More than 84 per cent of the world’s coral reefs have been affected by extreme heat stress in what has now become the most widespread coral bleaching event on record, scientists confirmed on Tuesday. The mass bleaching, which began in early 2023, has impacted reefs in at least 83 countries and territories, including biodiversity hotspots like Australia’s Great Barrier Reef, the Caribbean, the Indian Ocean, and reefs across the South Pacific and Southeast Asia.

This is the fourth global coral bleaching event ever recorded, and the second in the last decade, according to the US National Oceanic and Atmospheric Administration (NOAA). “As the oceans continue to warm, coral bleaching is becoming more frequent, more intense, and more widespread,” Derek Manzello, coordinator of the Coral Reef Watch programme at the US National Oceanic and Atmospheric Administration (NOAA), said.

A heat stress map released by NOAA’s Coral Reef Watch shows large parts of the Pacific and Caribbean oceans in dark red and purple – the highest alert levels for coral bleaching. The agency recently expanded its warning system to account for how extreme the heat stress has become, with the new levels indicating widespread bleaching and a high risk of coral death.

Bleaching occurs when ocean temperatures rise above normal for prolonged periods, forcing corals to expel the algae they rely on for food and colour. Left without this algae, corals turn white and become more vulnerable to disease and death. The current event, confirmed by NOAA and the International Coral Reef Initiative (ICRI), has already surpassed the previous record bleaching event from 2014–2017, which affected 68.2 per cent of reefs worldwide.

Read more: https://www.the-independent.com/climate-change/news/coral-bleaching-noaa-australia-florida-b2737825.html