In 2020, the Maldives faced a terrible environmental disaster, with roughly a quarter of its mangrove forests destroyed. A pioneering study has pinpointed the underlying culprit: record-high sea levels caused by the Indian Ocean Dipole (IOD) climate pattern. Maldives Mangroves are drowning in salty water, causing salinity stress and a slow decrease until death.

The Function of the Indian Ocean Dipole

The Indian Ocean Dipole (IOD) is a climatic phenomenon that influences wind, sea surface temperatures, and precipitation in the Indian Ocean basin. Warmer sea surface temperatures were seen in the western Indian Ocean, which includes the Maldives, during its positive phase from 2019 to 2020. This resulted in thermal expansion of ocean waters, due to which Maldives Mangroves are drowning in salty water, while the eastern Indian Ocean had cooler temperatures and lower sea levels.

The study, published in Scientific Reports on November 12, 2024, found that between 2017 and 2020, sea levels in the Maldives climbed by around 30 millimeters. This exceptional elevation exposed mangrove forests to seawater for an extended period of time, increasing soil salinity. Mangroves, especially those with low salt tolerance, such as Bruguiera cylindrica, struggled to survive in these conditions. This species lacks salt glands, rendering it particularly sensitive to salinity stress.

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Why Mangroves Matter?

Mangroves are among the world’s most productive ecosystems, providing significant ecological and economic advantages. These coastal forests serve as natural shields, safeguarding shorelines from erosion and storm surges, and they play an important role in climate regulation by sequestering large amounts of carbon. Aside from environmental benefits, mangroves benefit fisheries by serving as nurseries for various marine species, and they also help local economies by providing tourism opportunities.

Mangroves are critical to environmental stability in the Maldives, a 900-kilometer-long low-lying archipelago. With an average elevation of less than 1.5 meters above sea level, the islands rely significantly on these ecosystems to preserve the coastline and support wildlife. The Maldives has 15 mangrove species spread across over 150 islands, demonstrating its biological diversity. However, rising sea levels and increased human pressures pose severe challenges to these delicate ecosystems, emphasizing the crucial need for conservation measures to ensure their long-term viability.

Also Read: Why We Need To Conserve Mangroves?

Salt Stress and Feedback Loops

Lucy Carruthers and Vasile Ersek of Northumbria University’s Department of Geography and Environmental Sciences coordinated an interdisciplinary project to determine the extent and causes of mangrove dieback. They used satellite imaging, field research, sediment geochemistry, and tree ring analysis to identify the stressors.

Satellite photos revealed that increased sea levels resulted in a considerable migration of saline water into mangrove habitats, raising porewater salt levels. This stress was aggravated by high temperatures in 2020, which increased evapotranspiration and raised saline levels.

As salt tolerances were surpassed, sediment accretion—the process by which mangroves accumulate soil to adapt to rising sea levels—slowed. This resulted in soil submergence, triggering a positive feedback loop that accelerated the trees’ decline. The roots of damaged mangroves could not deal with the higher salt concentrations, resulting in widespread mortality.

Constraints on Adaptation

Unlike mangroves in bigger landmasses, those in the Maldives have distinct obstacles. The limited land area, coastal development, and little sediment deposition inhibit mangroves from spreading landward. Their inability to escape rising water levels makes them especially vulnerable. According to the study, 26% of Maldives Mangroves are drowning in salty water, with some losing more than half their mangrove cover. Notably, the dieback happened without large storms or local human activity, demonstrating the importance of climate-related causes.

Broader Implications for Small Island States

The disappearance of mangroves in the Maldives is a stark warning to other Small Island Developing States (SIDS). These countries are especially vulnerable to climate change because of their low elevations and reliance on coastal ecosystems.

The study used Guinea-Bissau in West Africa as an example, where 96% of small-scale fishers rely on mangroves for a living. Mangroves in the Caribbean increase the biomass of commercially significant species by more than double. Without mangroves, SIDS faces increased dangers from increasing sea levels and natural calamities.

Extreme weather events exacerbate these dangers. SIDS, for example, accounts for six of the ten countries most vulnerable to a storm that occurs once every 250 years. Cyclones produce the most significant relative yearly GDP losses in Antigua and Barbuda, while storm surges threaten nations such as the Bahamas and Dominica.

Also Read: Human-Driven Global Mangrove Forest Loss: An Overview

Learning from Previous Events

Learning from prior incidents in the Maldives and Australia illustrates mangroves’ vulnerability to climate-induced stressors. The 2015-2016 El Niño-Southern Oscillation (ENSO) events in Australia caused a 20-centimeter drop in sea level and extended drought, resulting in severe mangrove dieback. Such examples demonstrate the importance of coupled ocean-atmosphere processes in shaping coastal ecosystems. Scientists can use these patterns to better forecast and mitigate future impacts on mangroves. Adaptive management measures, such as rebuilding degraded mangroves and strengthening coastal resilience, are critical for preserving these ecosystems, which act as important carbon sinks and protect coasts from erosion and storm surges.

Urgent Need for Adaptive Strategies

Mangrove ecosystems will experience increased pressure as global sea levels are anticipated to rise by 0.43 to 0.83 meters by 2100 under various carbon emissions scenarios. The study’s authors emphasize the importance of adaptable conservation techniques, especially in vulnerable areas such as the Maldives.

Potential measures include:

• Sediment Management: Increasing sediment accretion using artificial ways to help mangroves survive.
• Community Engagement: Getting locals involved in conservation initiatives to guarantee that mangrove resources are used sustainably.
• Climate Mitigation: Reducing greenhouse gas emissions to slow sea-level rise.

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A Call to Action

The findings from the Maldives underline the vital importance of prioritizing mangrove conservation as part of the global climate response. These habitats are not only important for biodiversity, but they also act as natural buffers against the growing threat of climate change. Without prompt action, the loss of mangroves could have disastrous consequences for ecosystems and communities that rely on them. The dieback in the Maldives is a rallying cry for governments, researchers, and communities to work together. Protecting mangroves is not just an environmental necessity but also an issue of human survival.

Also Read: Mangroves’ Exceptional Heat Tolerance, Offers Resilience Against Global Warming: Study