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Coral Bleaching in 2024: Causes, Impacts, and Actions for Conservation

Writer's picture: Raphael MubangaRaphael Mubanga

In 2024, coral bleaching remains one of the most pressing and visible symptoms of climate change affecting our oceans. Corals, which support 25% of marine life, are increasingly under threat from rising sea temperatures, pollution, and human interference. Coral reefs are not only stunning marine ecosystems; they are vital to biodiversity, coastal protection, and human economies. Let’s explore the causes of coral bleaching, the recent events surrounding it, and the actions we can take to protect these crucial ecosystems.


A thriving coral reef captured by Atierra’s top Reef Ranger, Dave Prenter, at Motobu, Okinawa, Japan, on October 18, 2023.
A thriving coral reef captured by Atierra’s top Reef Ranger, Dave Prenter, at Motobu, Okinawa, Japan, on October 18, 2023.

What Is Coral Bleaching and Why Does It Matter?

Corals may look like plants or rocks, but they are actually animals that depend on a special partnership with tiny algae called zooxanthellae. These algae not only provide corals with food and oxygen through photosynthesis but also give them their vibrant color. In return, corals offer the algae a safe home, creating a mutually beneficial relationship.


However, when corals face stress from rising temperatures, pollution, or changes in water chemistry, they expel the zooxanthellae, leaving their white skeletons exposed‒a phenomenon known as coral bleaching. This leaves corals vulnerable, as they struggle to survive without their algae partners. However, not all hope is lost: if conditions improve, the zooxanthellae can return, allowing the corals to regain their color and health.


The Situation in 2024: Widespread Bleaching Events

In recent years, coral bleaching events have increased in both frequency and severity. 2024 has been no exception, with parts of the Great Barrier Reef, the Caribbean, and Southeast Asia experiencing alarming bleaching due to record-breaking sea temperatures and prolonged heatwaves. Extreme weather patterns like El Niño, combined with human-induced climate change, have exacerbated warm water stress on reefs.


According to a CNN report published on October 18, 2024, the astonishing ocean heat observed since February 2023 has led to the largest widespread coral bleaching on record. Even historically resilient coral reefs are struggling. Regions that typically experience natural temperature fluctuations and have evolved resistance to bleaching are now being affected.


Satellite data reveals that an alarming 77% of the world's coral reef areas‒spanning the Atlantic, Pacific, and Indian Oceans‒have experienced heat stress intense enough to trigger bleaching. Scientists warn that if ocean warming continues at this rate, up to 90% of coral reefs globally could be lost by the middle of this century.


Atierra’s top Reef Ranger, Dave Prenter, shared a compelling observation about the health of the reef in Motobu, Okinawa, Japan. During his routine weekly dive in November 2024, he compared its current condition to his visit a year ago.

In the shallow depths of 1–2 meters, I observed around 50% coral mortality, with higher fatalities further from the reef edge. However, at depths of 4–5 meters and beyond, approximately 80% of the coral appeared to have survived, showcasing a stark contrast in resilience across depths.

The same coral reef, now showing signs of bleaching, captured by Atierra’s top Reef Ranger, Dave Prenter, in Motobu, Okinawa, Japan, on November 17, 2024.
The same coral reef, now showing signs of bleaching, captured by Atierra’s top Reef Ranger, Dave Prenter, in Motobu, Okinawa, Japan, on November 17, 2024.

Why Are We Seeing More Coral Bleaching?

The primary driver of coral bleaching is rising ocean temperatures caused by climate change. However, other factors exacerbate the problem:


Ocean acidification

Increasing CO₂ levels in the atmosphere not only warm the oceans but also alter their chemistry. Acidification weakens coral skeletons, making them more susceptible to bleaching.

Pollution

Overfishing and destructive practices

Tourism and coastal development


 

How Can We Help?

Coral reefs are vital for ocean biodiversity, fisheries, and the livelihoods of communities relying on tourism and fishing. While the challenges are immense, there are impactful ways to contribute directly to coral reef conservation:


Collaborative coral reef monitoring

Collective, long-term, continuous monitoring is key to assessing reef health, predicting future challenges, and implementing effective solutions. This effort requires seamless collaboration among organizations, researchers, and individuals to maximize impact.

Contribute to conservation efforts

Share coral reef data

Engage in climate action

Participate in local clean-ups

Educate and raise awareness


All in all, Coral bleaching underscores the urgent need for collective action to protect our reefs, and Atierra is at the forefront of these efforts. By leveraging an open-source platform, we empower divers to contribute to reef conservation through photos and videos that enhance data collection and monitoring. These efforts directly support the global fight against bleaching by enabling timely interventions and fostering collaboration among individuals, scientists, conservationists, and local stakeholders. 

 

Share your coral reef photos and videos now to actively collaborate with marine communities, and collectively preserve these critical ecosystems for future generations.


 





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