The Ocean Floor is Dying: The Fourth Global Coral Reef Bleaching is Underway

The Ocean Floor is Dying: The Fourth Global Coral Reef Bleaching is Underway

Coral reef communities are fighting against the fourth global bleaching event. This phenomenon could become the most devastating one yet.

Coral reefs are underwater communities formed by colonies of small marine organisms called coral polyps. These ecosystems host a wide diversity of marine life, providing shelter and food to numerous species. However, they are undergoing a process known as bleaching, a phenomenon primarily caused by rising temperatures.

The Fourth Coral Reef Bleaching Event

When the ocean gets warmer, coral reefs kick out the tiny algae living in them, which give them color and food, making them turn white. The Coral Reef Watch by the National Oceanic and Atmospheric Administration (NOAA) has warned that these structures are facing the fourth big bleaching event in the last 30 years.

Coral bleaching has devastating consequences for marine ecosystems. As corals lose their algae, they weaken, and their mortality rate increases, affecting species that depend on them. Without reefs, there's less variety in the ocean, fishing gets hit, and natural defenses against coastal storms take a hit, which affects both nature and the people living near these reefs.

All around the world, coral reef communities are dealing with huge bleaching events, and they're not bouncing back easily. Along the shores of places like Mexico, Australia, and Kenya, many coral colonies have lost their color, making them look like ghosts in the water. The International Coral Reef Initiative (ICRI) says there are reefs in over a hundred countries, even though they only cover a tiny bit (0.2%) of the ocean floor, they're home to a quarter of all sea species.

Since February 2023, at least 54 countries and territories have experienced massive bleaching of their reefs due to the warming of surface ocean waters caused by climate change and the El Niño phenomenon, according to NOAA.

qui nguyen
© qui nguyen -

Why Does The Coral Reef Bleaching Happen?

As the oceans keep heating up, coral bleaching is becoming more common and severe, says Derek Manzello, who coordinates the Coral Reef Watch.

Bleaching events are triggered by anomalous water temperatures prompting corals to expel the colorful algae residing in their tissues. Without these algae to provide nutrients, corals cannot survive. 

The coral bleaching phenomenon recurred last year in the Caribbean, subsequently spreading to the Great Barrier Reef in Australia, as well as the coasts of Brazil, Tanzania, Mauritius, the Red Sea, and the Persian Gulf. For it to be classified as global, this event must significantly impact the three ocean basins: Atlantic, Pacific, and Indian, over 365 days.

The 2024 bleaching event coincides with the El Niño phenomenon, characterized by elevated sea temperatures. Last year witnessed record-breaking sea surface temperatures since 1979, exacerbated by climate change, raising concerns regarding the long-term recovery prospects of reefs amidst prolonged thermal stress.