Extreme Heat and Coral Reefs: What It Means for the Maldives

With World Ocean Day being observed on June 8, and increasing discussions on potential risks of El Niño, this is a timely moment to reflect on the importance of coral reefs, one of the Maldives’ most vital ocean assets. Coral reefs cover less than 0.1% of the ocean floor globally, yet they support over 25% of marine life. In the Maldives, their importance goes far beyond sustaining biodiversity. Across its vast number of islands, Maldives depends on healthy reef systems. Coral reefs are fundamental for the country’s two most important sectors – tourism and fisheries. They also play a critical role in climate resilience by functioning as natural barriers against coastal hazards. Even the white sandy beaches and lagoons that define the country are formed and replenished by living reef organisms. Protecting coral reefs, therefore, is not just an environmental priority; it is fundamental to the country’s economy, culture, coastal safety, and long-term survival.

Coral reefs across the world are under increasing pressure due to ocean warming. Particularly, the Indian Ocean has been warming faster than the global average, exposing Maldivian reefs to repeated and bleaching stress. When ocean temperatures remain unusually high, corals expel the algae that give them color and energy, a process known as coral bleaching. While bleached corals are not immediately dead, prolonged heat can lead to widespread coral mortality. El Niño, a recurring climate pattern that shifts warm ocean waters across the Pacific, can amplify these risks even further. Historically, though not very common, Maldives have experienced few major bleaching events due to El Nino. One of the most severe bleaching events on record occurred in 1998, when an El Niño-driven marine heatwave killed up to 90% of corals in some shallow reef areas.  This event caused a decrease in coral cover from approximately 40 percent to less than 2 percent. The recovery took about 10 years. Subsequent events in 2016, 2019, and 2020 struck reefs that had only partially recovered, reducing the time available for regeneration and accelerating long-term degradation. Normally, shallow reefs (up to a depth of 5m) are the most affected by bleaching. However, the mass bleaching due to another El Niño in 2016, affected not only 66% of shallow reefs, but also 77% of deep-sea reefs (7m to 13 m). Furthermore, 72% corals in sheltered sites and 74% of corals in exposed sites were bleached, causing another one of the largest recorded episodes of mass bleaching in the Maldives. Reefs in the Maldives are naturally well connected, which means less impacted sites can supply larvae to damaged sites, helping in faster regeneration. However, when bleaching events become more frequent and severe, it can weaken nature’s own recovery process and slow down long-term regeneration. This is why tracking coral heat stress in both the short and long term is important, as it identifies where reefs are under repeated pressure, where natural recovery may be weakening, and where restoration efforts should be targeted.

Tracking Heat Stress in the Maldives

To better understand these risks, ESCAP’s analysis, conducted under a CARA-funded project from the UK, examines how ocean temperatures are rising  over time and the potential impacts on reefs in Maldives. Using historical observations (1985–2019) and future climate projections, the analysis tracks “severe heat-stress days”, a measure of how often reefs are exposed to conditions that can trigger coral bleaching. Levels above 8°C-weeks signal severe bleaching and possible coral loss.

Figure: Projection of heat stress level in long term under two different climate scenarios

Historically, severe heat stress across Maldivian reefs was largely limited to exceptional events, particularly those linked to El Niño. However, projections suggest that this pattern is changing rapidly, with future heat stress expected to intensify unevenly across different parts of the country. Under a moderate climate projection scenario (SSP2-4.5), analysis show a gradual increase in reef exposure to heat stress, starting from southern atolls. In the near term (2021–2040), nearly entire reef areas remain at very low and low heat risk. Early signs of change appear in atolls such as Gaafu Dhaalu, Gaafu Alifu, Gnaviyani, Seenu (Addu), Dhaalu, and Thaa, where risk is low but marine warming is projected to increase.

By mid-century (2041–2060), nearly 36% of reef areas are projected to shift into moderate stress. During this period, several atolls in southern and central parts, including Dhaalu, Faafu, Thaa, Gaafu Alifu, Gaafu Dhaalu, and Gnaviyani are expected to face moderate risk .

In the long term (2061–2080), the change becomes more pronounced across the entire country. And the reef exposure is projected to be split evenly between moderate and high heat stress. Based on these projections, southern and central atolls such as Seenu (Addu), Gnaviyani,  Gaafu Dhaalu , Meemu, Vaavu, and Laamu could start facing higher risk of coral bleaching. Although relatively less exposed, northern atolls, including Haa Alifu, Haa Dhaalu, and Shaviyani, are also projected to shift toward moderate stress in the long term.

Under more pessimistic and high-emissions scenario (SSP5-8.5), in the near term (2021-2040), many southern atolls, including Seenu, Gnaviyani, and Gaafu Dhaalu are projected to experience low stress. By mid-century, high stress could become dominant in these regions and expand toward the northern parts of the country. By 2080, up to 93% of reef areas across the Maldives could shift to very high stress category. These include atolls such as Baa, Raa, Alifu Alifu, Alifu Dhaalu, Kaafu (including Malé), Dhaalu, Faafu, Laamu, Thaa, and the Gaafu. Even in the northernmost atolls, which are expected to warm comparatively slowly, reefs are projected to experience  high to very high stress.

From Impact to Action: Voices from the Reef

Community-based restoration initiatives, such as those led by Muraka in Dharavandhoo, are helping with reef recovery. Their work focuses on coral gardening by growing coral fragments in underwater nurseries and transplanting them to damaged sites.

Making reef frames for Dharavandhoo, Muraka Project
@Ikraam Ali/Muraka Farm
 

As Ikraam Ali, one of the Muraka team members, reflects:

“Over the past decade, we’ve seen noticeable changes. Some areas that were once full of healthy coral have been affected by warming seas and bleaching events. At the same time, we’ve also seen encouraging signs of recovery especially where restoration is taking place.”

The impact of recent bleaching events has been deeply felt: “Many corals lost their color and some didn’t survive. It was difficult to witness, but it strengthened our commitment to helping them recover.”

A key element of success is working with nature, not against it.

“The Maldives has ideal conditions for coral growth, and when local communities, visitors, and conservationists work together, the results can be amazing.”

Muraka’s work also highlights an important scientific insight: corals that have survived past bleaching events may hold the key to future resilience. By selecting and propagating these more tolerant colonies, restoration efforts can help reefs adapt to warmer conditions.

At the same time, restoration is not without challenges: “We do all of our underwater work on a single breath, without scuba gear. Every task depends on how long we can stay underwater. Strong currents and rough weather can also damage nursery structures, making repairs difficult.”

Youth engagement
@Ikraam Ali/Muraka Farm

Despite these hurdles, community engagement remains a strong foundation of success.
“The response has been very positive. People understand how important reefs are to our islands, and many are eager to take part. Young people bring energy, and tourism operators help connect visitors to conservation.”

Perhaps most importantly, these efforts show that recovery is possible:

“Through years of protection and restoration, we’ve stepped back and watched nature beautifully heal itself.”

Alongside restoration, a broader set of adaptation strategies is emerging in the Maldives:

• Protecting thermal refuges where reefs are naturally less exposed to heat stress
• Expanding marine protected areas to reduce fishing pressure and allow ecosystems to recover
• Reducing pollution through improved wastewater management and sustainable coastal development
• Integrating reef conservation into the blue economy, recognizing the direct link between healthy reefs and economic resilience

In addition to these efforts, the government is running a National Coral Reef Monitoring program, which was initiated in response to the 1998 mass bleaching event. It provides a Coral Reef Monitoring Framework and a database developed for marine monitoring. These approaches reflect a growing recognition that reef conservation is not a standalone issue; it is central to national development, food security, and climate resilience.

The Way Forward

The future of coral reefs in the Maldives will depend on decisions made in the coming years. Global action on climate change remains essential, as no level of local intervention can fully offset the impacts of rising ocean temperatures. At the same time, local and national efforts can play a critical role in strengthening reef resilience and supporting recovery.

Coral reefs have sustained the Maldives for generations. Today, they are facing unprecedented challenges but also benefiting from unprecedented attention and action.

The message is clear: protecting coral reefs means protecting the Maldives itself, its people, its economy, and its future.

Authors:

Leila Salarpour Goodarzi, Associate Economic Affairs Officer, ESCAP

Akash Shrivastav, Consultant, ESCAP

Parvathy Subha, Consultant, ESCAP

Elisa Belaz, Consultant, ESCAP

Suhyeon Shin, Intern, ESCAP