Mangroves
How Mangroves Combat Rising Sea Levels
Mangroves as a nature-based solution for climate change offer a compelling case for managing rising sea levels. This is especially true when looking at their strategic implementation in Singapore and looking forwards to their potential applications in the Philippines. Native to tropical coastal regions, mangroves thrive in environments similar to those of both countries, but have suffered significant ecosystem losses due to land reclamation projects.
The dense interlocking roots and branches of mangroves play a crucial role in mitigating the impacts of rising sea levels. By slowing down the flow of water, roots reduce the erosion of shorelines and lessen the impact of waves on inland areas. Additionally, they facilitate the buildup of sediment around their roots, which can lead to an increase in land elevation. This process helps offset the effects of sea-level rise by stabilizing and gradually raising the coastline.
These ecosystems are incredibly effective at sequestering carbon, storing up to four times more than rainforests in the seabeds beneath them. Additionally, they improve water quality by filtering pollutants and provide critical habitats for marine life.
Singapore's initiative, supported by a public-private partnership with the Overseas Chinese Banking Corporation, completed a mangrove forest with 9,000 trees by 2026. Results estimated that the project single-handedly induced the capture of nearly 30 million kg of CO2, while reducing storm wave heights by over 75%.
Despite these optimistic numbers, however, Singapore has since deemed mangroves alone an insufficient measure for combating rapidly rising sea levels due to their extended maturation timeline and the inefficient trade-off of real estate required to accrue sufficient benefits. As such, the country looks towards combining mangrove restoration efforts with engineering feats in the form of stone and concrete revetments.
Integrated Mangrove & Revetment Approach in Pulau Tekong, Singapore
These low-lying structures are built along shorelines to absorb the energy of incoming waves and reduce erosion. Revetments typically consist of layers of large rocks or concrete blocks that are placed along the coast. When integrated with an initial boundary of mangroves, the two approaches work synergistically to create a more comprehensive defense mechanism against coastal erosion and rising sea levels. The revetments provide immediate physical protection to coastlines, crucial in areas where mangrove forests are still young and not fully established. As the mangroves grow, their root systems begin to stabilize the sediment, gradually assuming the role of erosion control.
Furthermore, as the mangroves enhance sediment deposition by trapping and stabilizing sediments, additional protection is offered to the revetment structures from wave action. Over time, this combination reduces reliance on engineered solutions as the growing mangrove ecosystems offer a sustainable, self-maintaining alternative that becomes increasingly effective, promoting a more natural and self-sustaining coastline. This integration of biological enhancement with physical barriers offers a durable and economically viable solution, aligning with global trends towards nature-based solutions for coastal management.
This case study of Singapore's mangrove forests offers critical insights for broader applications. Although not fully tested due to resource constraints at the time, the effectiveness of these measures was actually corroborated by smaller-scale initiatives in the Philippines as of 2022. Designated protected areas like Malapaya Park, Palawan marked progress, but were initially insufficient in capacity and would require testing on a larger-scale. Moreover, implementation of revetments would greatly improve the efficacy of this natural sea-level barrier.
Mangrove Forest at Malapaya Park, Palawan
Nonetheless, the effectiveness of mangroves was highlighted during a December 2021 typhoon that struck North Palawan after which locals reported extensively minimized damage to households and wildlife due to these natural barriers. This success not only underscores the protective capabilities of mangroves, but also suggests that enhancing such ecosystems could help decongest urban areas like Manila by promoting in-migration to rural areas with rich marine life, driven by projects similar to those on Palawan island. Thus, investing in mangrove restoration and supportive engineering feats is not only a sustainable response to climate change but also a strategic move towards ecological and socio-economic resilience.
In 2030, the Philippines achieved its goal to increase mangrove coverage by 20%, inspired by Singapore’s projects, and now plans to grow an additional 40% by 2060 based on the success of the program. Research completed from the World Bank after the 2030 initiative concluded that 100 meters of mangrove forest reduced wave energy by 66%, lowered annual flooding risks for 613,000 people, and saved approximately $1 billion in property damage.