4th Mass Coral Reef Bleaching and NOAA's Findings

4th Mass Coral Reef Bleaching and NOAA’s Findings

The world is currently on the brink of witnessing the 4th mass coral reef bleaching event, a major threat to the health and existence of these vital ecosystems.

Table of Contents

Context: According to the U.S. National Oceanic and Atmospheric Administration (NOAA), the world is on the verge of a fourth mass coral bleaching event which could see wide swathes of tropical reefs die.

What Are Corals and Coral Reefs?

Corals are marine animals known as polyps that form a symbiotic relationship with algae called zooxanthellae.
- The zooxanthellae provide corals with food and oxygen, while corals offer a protective habitat.
Coral reefs are structures made of limestone, composed of coral polyps, found in tropical climates.

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Coral Bleaching

Coral bleaching occurs when corals, under stress such as high temperatures or pollution, expel their symbiotic algae.
Bleached corals turn white and struggle to survive without the algae.
If stressors are mitigated promptly, corals may recover as zooxanthellae return.
Reefs are crucial for marine biodiversity, coastal protection, and carbon absorption.
They contribute to the livelihoods and safety of human communities.

NOAA’s Findings on Coral Bleaching

The world may be facing its fourth mass coral bleaching event, with past events in 1998, 2010, and 2014.
A global bleaching event is indicated by bleaching across three ocean basins: the Atlantic, Pacific, and Indian Oceans.
The 2014-2017 global bleaching event resulted in the loss of about one-third of the Great Barrier Reef’s corals.
Around 15% of the world’s reefs experienced significant coral die-offs in the last event.
The Caribbean experienced its worst coral bleaching record after the Northern Hemisphere’s summer last year.
Coral bleaching is linked to El Niño and exacerbated by climate change-induced temperature rises.
The first 12-month period with average temperatures exceeding 1.5 degrees Celsius above pre-industrial levels has been recorded.
A 1.5C temperature increase is a critical threshold for coral survival, with potential loss of 90% of the world’s corals.