Coral Reefs Feel the Heat

Healthy coral reefs brim with life and color. Each generation of coral builds upon the last, creating vast underwater structures that support more than a quarter of all marine species and our own well-being. In Hawaiʻi, the reefs along our coasts are environmental, economic, recreational and cultural treasures that:

• block up to 97% of the wave energy hitting our coastlines
• provide flood protection to people, property, and jobs valued at more than $836 million
• support nearshore fisheries worth $13.4 million
• contribute more than $1.2 billion through reef-related tourism to the state’s economy
• create world-renowned surf breaks, and
• connect us to our islands’ natural and cultural heritage

Our Reefs are Stressed

Despite their immensity and importance, our reefs are vulnerable. Land-based pollution and overharvest of reef fish have contributed to declines of up to 60% in living coral cover in some areas in Hawai‘i over the past 50 years—a loss that is linked to a 75-90% decline in reef fish populations statewide. These already stressed coral reefs are more vulnerable to marine heatwaves, which trigger coral bleaching.

The marine heatwave associated with the 2015/2016 El Niño produced record-breaking ocean temperatures across the central Pacific, leading to widespread coral bleaching across Hawai‘i and a loss of 30% of living coral cover statewide. Scientists expect the developing 2026/2027 El Niño to bring even warmer waters to Hawaiʻi, heightening the urgency of efforts to protect, monitor and restore our precious coral reefs.

What Is Coral Bleaching?

Corals are animals that live in partnership with microscopic algae. These algae provide much of the energy corals need to survive and they give reefs their vibrant colors. But when ocean waters get too warm for too long, that partnership can break down. The algae leave the coral, exposing the coral’s white skeleton, hence the term “bleaching." Bleached corals are still alive, but they are stressed and more vulnerable to disease and death, especially if high temperatures persist.

How We Can Help Reefs

While tackling climate change requires coordinated global action, local efforts can help reduce its impacts on coral reefs. Science shows that healthy coral reefs are more resilient, meaning they are better able to resist or recover from bleaching than reefs already weakend by pollution, overuse and other stressors. That’s an important reminder that local action matters more than ever.

Here in Hawai‘i, we work with government, academic, business and community partners to protect and restore reef health by reducing local pressures and strengthening stewardship. Together, we are working to:

• Reduce sediment and nutrient flows to reefs by restoring mauka habitats to minimize erosion, improving retention systems and restoring makai habitats so they can better capture, absorb and filter pollutants.
• Restore reef fisheries by supporting place-based co-management that integrates modern tools with traditional stewardship approaches.
• Reduce untreated wastewater flows to coastal waters and reefs by assisting with the transition to upgraded treatment systems. 
• Advance coral restoration science and statewide collaboration through the Hawai‘i Emergency Reef Restoration Network, a group of reef practitioners trained to recover and reattach coral colonies in response to damaging events, such as large swells and storms. 
• Build local capacity for stewardship by uniting to advance shared priorities, collaborating on research and monitoring, and sharing insights, knowledge and lessons learned through peer networks and partnerships that foster collective action.

As we continue to minimize local pressures, we are also preparing to closely monitor and respond to the impacts of the 2026/2027 El Niño. Our expanded drone-based monitoring, in-water surveys and thermal-tolerance studies will help to identify which reefs and corals are most vulnerable and which are showing signs of resilience. That information will help ensure that we focus recovery efforts on the reefs and interventions where they can have the greatest impact.

Vanishing Mural Depicts Coral Bleaching

Inspired by the beauty and fragility of our environment, Hawai‘i-born artist Jana Ireijo creates ephemeral “vanishing” murals that illustrate the impacts of climate change on vulnerable species and habitats. She created this mural, comprised of iconic Hawaiian marine life, to show how bleaching is impacting coral reefs along our coasts. 

“My mission with these murals is to raise awareness and inspire a sense of urgency to take action – to let the murals vanish so our natural environment does not,” said Ireijo. “I was raised in Hawaii, so drawing attention to the issue of coral bleaching is especially meaningful to me. My hope is that this mural will help generate the support and action needed to protect coral reefs.”

Commissioned by TNC and presented in partnership with the Maui Ocean Center Marine Institute, the mural is on display at the Maui Ocean Center.