The Earth is Experiencing its Fourth Global Coral Bleaching Event

Scientists at both the International Coral Reef Initiative and the National Oceanic and Atmospheric Administration (NOAA) have confirmed that Earth is currently experiencing its fourth global coral bleaching event, the second in the past decade.

What is a global bleaching event?

In order for the event to be considered global, bleaching must be confirmed within each ocean basin. Significant bleaching events have occurred between February 2023 and April 2024 in both the Northern and Southern Hemisphere, including Australia’s own world-famous Great Barrier Reef.

Mass bleaching of coral reefs has been confirmed in at least 53 countries, territories, and local economies, including regions like Florida, the Caribbean, Australia, and large areas of the South Pacific. The final area to confirm reports of bleaching has been the Western Indian Ocean including Tanzania, Kenya, the Seychelles, and off the western coast of Indonesia.

Coral bleaching in the Maldives

Derek Manzello, Ph.D., NOAA CRW Coordinator explains, ‘As the world’s oceans continue to warm, coral bleaching is becoming more frequent and severe. 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’.

Can anything be done to prevent this?

Amidst this bad news, there’s a glimmer of hope for the future.

If the stress put on coral is reduced, they have a good chance of recovery. This means it is possible to avoid coral mortality so they can happily continue to support biodiversity and vital ecosystem services.

The International Coral Reef Initiative (ICRI), currently co-chaired by NOAA and the US Department of State, is actively working to reduce coral stress by advancing coral interventions and restoration in response to climate change impacts.

ICRI also develops and shares best practices for effective coral reef management and has launched the Coral Bleaching Hub to provide resources on coral bleaching.

In response to this major global problem, ICRI will host a webinar on the 14th of May 2024, to discuss the status of the fourth global bleaching event and the role of the global coral reef community. If you’re interested, you can register for the event on ICRI’s website.

What exactly is coral bleaching?

Coral bleaching is a stress response that occurs when corals experience environmental stressors, most commonly triggered by prolonged increases in anomalous ocean temperatures.

Corals have a symbiotic relationship with microscopic algae called zooxanthellae, which live within their tissues and provide them with nutrients and their venerated vibrant colours. When corals are stressed, they expel these algae, causing them to lose their colour and turn white or to ‘bleach’, which can lead to death.

What is NOAA?

The National Oceanic and Atmospheric Administration (NOAA) is a U.S. federal agency responsible for studying and understanding the Earth’s atmosphere and oceans.

When it comes to coral reefs, NOAA plays a key role in monitoring and managing these ecosystems through its Coral Reef Conservation Program and Coral Reef Watch program. Both initiatives focus on preserving coral reef health by tracking environmental changes and implementing conservation and restoration strategies.

Images thanks to The Ocean Agency / Ocean Image Bank