The Fourth Global Coral Bleaching Event

The Ocean Agency - Fluorescing | Ocean Image Bank

NOAA and ICRI Confirm Fourth Global Coral Bleaching Event

This press release is available to download in English, French and Spanish (.pdf)

WASHINGTON D.C (Monday 15th April 2024) – The world is currently experiencing its fourth global coral bleaching event, according to NOAA scientists and ICRI’s network of global coral reef scientists, the second in the last 10 years.

Bleaching-level heat stress, caused by prolonged increases in anomalous ocean temperatures, as remotely monitored and predicted by NOAA’s Coral Reef Watch (CRW), has – and continues to be – extensive across the Atlantic, Pacific, and Indian Oceans.

“From February 2023 to April 2024, significant coral bleaching has been documented in both the Northern and Southern Hemispheres of each major ocean basin,” said Derek Manzello, Ph.D., NOAA CRW coordinator.

Mass bleaching of coral reefs, since early 2023, has been confirmed in at least 53 countries, territories, and local economies, including Florida (U.S.A), the Caribbean, the Eastern Tropical Pacific (including Mexico, El Salvador, Costa Rica, Panama, and Colombia), Australia’s Great Barrier Reef, large areas of the South Pacific (including Fiji, Vanuatu, Tuvalu, Kiribati, and the Samoas), the Red Sea (including the Gulf of Aqaba), the Persian Gulf, and the Gulf of Aden.

Bleaching must be confirmed within each Ocean basin to make a final determination of a global bleaching event. Reports have now been confirmed of widespread bleaching across parts of the Western Indian Ocean, including Tanzania, Kenya, Mauritius, the Seychelles, Tromelin, Mayotte, and off the western coast of Indonesia.Reports also account for widespread bleaching across parts of the south Atlantic, along the northeast coasts of Brazil.

“As the world’s oceans continue to warm, coral bleaching is becoming more frequent and severe,” Manzello said. “When these events are sufficiently severe or prolonged, they can cause coral mortality, which can negatively impact the goods and services coral reefs provide that people depend on for their livelihoods.”

Where coral bleaching results in mortality, especially on a widespread scale, it impacts economies, livelihoods, food security, and more. However, it is important to remember that coral bleaching does not always lead to coral death. Rather, if the stress driving the bleaching diminishes, corals can recover, with reefs maintaining their biodiversity and continuing to provide the ecosystem services that we rely on.

“Climate model predictions for coral reefs have been suggesting, for years, that bleaching impacts would increase in frequency and magnitude as the oceans warm,” said Jennifer Koss, director of NOAA’s Coral Reef Conservation Program (CRCP).

This global event requires global action. The International Coral Reef Initiative (ICRI), a partnership of 101 international members, currently co-chaired by NOAA and the US Department of State, is steadfast in applying resilience-based management actions for coral reefs. In response to the three previous global bleaching events as well as regional and local events, ICRI and its members have advanced coral interventions and restoration in the face of climate change. ICRI develops, and shares, best practices for the effective management of coral reefs through the implementation of its Plan of Action.

NOAA has incorporated resilience-based management practices, increasing  the emphasis on coral restoration, into its 2018 strategic plan, and funded a National Academies of Sciences’ study, leading to the publication of the 2019 Interventions to Increase the Resilience of Coral Reefs. 

Koss said: “We are on the frontlines of coral reef research, management, and restoration, and are actively and aggressively implementing the recommendations of the 2019 Interventions Report.”

The 2023 heatwave in Florida (U.S.A) was unprecedented; starting earlier, lasting longer, and with recorded temperatures higher than any previous event in the region. During the heat stress event, NOAA deployed the 2019 recommended interventions, building a valuable knowledge base and made significant strides, through its “Mission: Iconic Reefs program”, to offset some of the negative impacts of global climate change and local stressors on Florida’s corals including moving coral nurseries to deeper, cooler waters and deploying sunshades to protect corals in other areas.

Global bleaching events do not affect all coral reefs equally and require a suite of global, regional, and local interventions. This emphasizes the importance of regularly monitoring coral reef ecosystems and not just during bleaching events. Networks such as the Global Coral Reef Monitoring Network, an operational network of ICRI, and the US Coral Reef Task Force, provide mechanisms for reporting on the impact of bleaching on the World’s coral reefs, alongside regional bleaching observation networks.

“Long-term data on of coral reef condition can put events like this into context. They allow us to quantify coral mortality, track recovery, and identify areas that don’t recover naturally and may need further protection or a helping hand through innovative interventions”, said Dr Britta Schaffelke, Manager International Partnership at the Australian Institute of Marine Science and Global Coordinator of the GCRMN.

To share key messages and resources about coral bleaching, its impacts, causes and solutions currently being implemented and developed, ICRI has developed the “Coral Bleaching Hub” to support responses, policy and planning, and encourage global cooperation.

ICRI will be hosting a webinar on Tuesday 14th May 2024 to present and discuss the status of the 4th Global Bleaching Event, and the role of the global coral reef community. Register your interest to attend the webinar here.

This ICRI Press Release was developed in collaboration with NOAA and is adapted from NOAA’s Press Release (EN) available here (.pdf).

Use the buttons to below to download the translated version of the Press Release, register for the webinar and access the ICRI Coral Bleaching Hub, as well as supporting media available below:

Coral reef bleaching time-series images are to be credited to “Leslie Henderson / NOAA” and quote cards credited to “The International Coral Reef Initiative”.