Fourth Global Mass Coral Bleaching Prompts Emergency UN Measures

The United Nations has issued an urgent call for increased funding to protect coral reefs, which are facing extinction due to the most extensive mass bleaching event recorded.

Their data shows 77 percent of the world’s coral reefs are affected by bleaching.

It is the largest mass bleaching event on record and the fourth in all of human history, the United Nations Capital Development Fund (UNCDF) said.

Global leaders and climate scientists have bolstered the issue’s momentum at the COP16 biodiversity summit in Cali, Colombia, where an emergency session—typically scheduled to address international conflicts and natural disasters—was held.

“With the window to protect these ecosystems closing rapidly, world leaders must act now,” said Peter Thomson, the U.N. Secretary-General’s Special Envoy for the Ocean.

Signs of global-scale coral bleaching were first observed in 2023, stretching deep into this year.

What Causes Coral Bleaching?

The UNCDF warned that this fourth mass bleaching event is a serious threat to ecosystems that support 25 percent of marine life and nearly a billion people worldwide.

Sudden increases in water temperature, often due to climate change, are the most common cause. Even a 1-2°C rise over a prolonged period can trigger bleaching.

Other environmental stressors, such as increased CO₂ absorption and runoff from sewage, and industrial activities, leads corals to expel algae, their primary food source.

This loss causes the coral to lose color and suffer from malnutrition, leaving them susceptible to disease and death.

The Florida Coral Reef and Australia’s Great Barrier Reef, the third and largest reef ecosystems, respectively, have already seen extensive bleaching, with 90 percent of the Great Barrier Reef’s coral affected in 2022.

Surrounding sea temperatures are the hottest they’ve been in 400 years, affecting food chains across the ocean.

“It is estimated that roughly 25 percent of all marine species associate with coral reefs at some point in their lives,” National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch Coordinato Derek Manzello told Newsweek earlier in April.

“Thus, the large-scale death of corals and degradation of coral reefs threatens the survival of 1 in 4 of every living organism in the ocean.”

Almost $30 Million Pledged for Reef Protection

In response, countries including New Zealand, the United Kingdom, Germany, and France pledged nearly $30 million in new contributions to the U.N. Coral Reef Fund, which aims to gather up to $3 billion by 2030 to support reef conservation initiatives.

“Protecting our ocean and its precious habitats is fundamental to life on earth,” U.K. Minister for Nature Mary Creagh said, noting that reefs are on the verge of collapse from “global heating, acidification, disease, and pollution.”

Further financial commitments are anticipated at next year’s U.N. Ocean Conference in Nice, France, taking place across June 9-15, 2025.

Officials see this conference as an opportunity to secure an additional $150 million in donations to support global coral protection.

Building on COP16 Momentum Beyond Columbia

Alongside this, mass bleachings by definition are occurring beyond El Niño periods—a climate phenomenon characterized by unusually warm sea surface temperatures in the central and eastern Pacific Ocean, near the equator.

El Niño events typically occur every 2-7 years and last for several months, not years.

Kenyan marine ecologist David Obura, who leads the Coastal Oceans Research and Development in the Indian Ocean, East Africa, stressed the urgency of sustained interventions, warning that mass bleaching events are no longer short-term bursts of environmental damage.

He explained that initially, the first mass bleaching happened in 1998, the second between 2011-2013, the third in 2016.

“They’re lasting more than one year at a time, which is worrying,” he said during the U.N. emergency session.

This article includes reporting from The Associated Press