84% of world’s corals impacted by heat stress – scientists

MANILA, Philippines — Bleaching-level heat stress has impacted 84 percent of the world’s coral reefs, with scientists noting that the Philippines is among 82 countries and economies severely affected.

The Philippines has one of the richest coral reef systems on Earth, according to experts.

The study showed that since last January, bleaching events have been rapidly getting worse due to human-induced climate change, which threatens the existence of live coral reefs.

According to the latest report, the first bleaching event in 1998 saw 21 percent of reef areas affected. In 2010 this rose to 37 percent and went up to 68 percent from 2014 to 2017.

Scientists said corals bleach when water temperatures are too high, but if water temperatures return to normal, they can recover. If water temperatures stay too hot for too long, corals will die.

In 2023, the National Oceanic and Atmospheric Administration added three new levels to their bleaching alert scale to indicate the heightened risk of mass coral mortality.

University of the Philippines Diliman Marine Science Institute assistant professor and physical oceanographer Charina Lyn Amedo-Repollo reinforced the significance of the global bleaching event.

“The most intense global coral bleaching event ever recorded underscores the urgent need for both global and local action to protect vulnerable reef ecosystems, including those in the Philippines,” Repollo said.

Repollo added that while the country contributes only about 0.5 percent of global greenhouse gas emissions, its proactive commitment to climate resilience and emission reduction is crucial, not just for national sustainability, but as a meaningful part of the global effort to combat climate change.

“Locally, expanding and effectively managing marine protected areas can significantly enhance reef resilience by reducing stressors such as overfishing and land-based pollution, while also supporting natural recovery processes. When these efforts are integrated with community-led conservation, innovative restoration approaches, and international collaboration, they offer the best hope for Philippine reefs to survive and recover in the face of accelerating ocean warming,” she said.

Scientists said last year was the hottest on record and the first to reach over 1.5°C warmer than pre-industrial times, due to human-induced climate change.

Experts added that this contributed to record-breaking ocean temperatures, and triple the previous record number of marine heatwaves around the world.

Reefs provide $10 trillion in benefits like food, jobs and coastal protection.

Scientists said losing coral reefs undermines efforts to achieve sustainable development, alleviate poverty, and ensure food security, adding that climate-change induced coral loss could cost $500 billion annually by 2100.

Experts said that although corals are in danger, a combination of local conservation measures and rapid emissions cuts can still help them to survive the 21st century.

The International Coral Reef Initiative has developed eight key policies to guide the urgent action needed, and experts estimate that spending on corals needs to increase sevenfold.

Additionally, limiting global warming to as little above 1.5 degrees Celsius as possible is necessary to give these coral conservation measures a chance to work. Current climate plans put the world on track for approximately 2.7 degrees Celsius of warming.