How the Tiny Island City-State of Singapore Fights Rising Sea Levels

During a half-century of independence, Singapore has fought to expand its territory, inch by hard-won inch. On the tip of the Malaysian peninsula, the island city-state piled up sand to expand its coastline and reclaim land from the sea.

In that time, Singapore has grown by one-quarter, adding landmass more than twice the size of Manhattan. At 284 square miles, Singapore is now approaching the size of all five boroughs of New York City. It plans to grow an additional 4% by 2030. It’s a striking accomplishment, given that many other coasts are receding because of rising sea levels, a result of climate change.

“We are not planning to lose any inch of land permanently,” says Ho Chai Teck, a deputy director at PUB, the government agency coordinating the effort to save the nation’s shores. “Singapore will build a continuous line of defense along our entire coast. This is something that we take very seriously.”

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Roughly one-third of Singapore is less than 16 feet above sea level, low enough for flooding to cause punishing financial losses. Some of its most prized property sits on vulnerable land: the skyscrapers overlooking the Marina Bay waterfront, known for its luxury mall and casino, and the towers that house giant banks such as Singapore-based DBS Group Holdings Ltd., Southeast Asia’s largest, and UK-based Standard Chartered Plc.

Assuming 1.5C of warming, prime real estate in the city worth S$70 billion ($50 billion) faces a high risk of flooding, according to Bloomberg estimates using data from real estate company CBRE Group Inc. Another endangered, and vital, part of the country is Jurong Island, where Shell Plc and Exxon Mobil Corp. have oil and petrochemical operations.

“You’ve got small island nations, but they don’t have this much economic wealth,” says Benjamin Horton, a professor at Nanyang Technological University in Singapore who studies sea-level change. “The actual value of every square meter in Singapore is off the charts. This is a country more susceptible to sea-level rise than virtually any country in the world.”

In 2019, Prime Minister Lee Hsien Loong said that Singapore would need to spend S$100 billion over the next 100 years to protect against rising sea levels. The government has since put S$5 billion toward a coastal and flood protection fund. “Both the Singapore Armed Forces and climate change defenses are existential,” he said then. “These are life-and-death matters. Everything else must bend at the knee to safeguard the existence of our island nation.”

A day’s bike ride along Singapore’s coastal paths will take you past glittering skyscrapers and scenic dams, beaches and mangrove swamps—diverse scenes that make clear how the country must carefully tailor its approach. What Singapore does will be keenly watched by other populous coastal cities such as Bangkok, Miami, New York and Shanghai.

Fortifying the city

On a recent weekday, tourists and locals fly kites on a ­towering structure with dazzling views of Singapore’s skyline. But what they’re standing on is much more than an attraction. It’s a S$226 million dam called the Marina Barrage. Inside, seven giant pumps drain excess water into the sea during high tide and extreme rainfall. Currently, some kind of human-made barrier protects 70% of Singapore’s coastline. But the city-state will have to reinforce and improve those shields as tropical storms increase and sea levels rise.

The Hydroinformatics Institute and National University of Singapore are working with PUB to build a computer model simulating the combined effects of sea-level rise and rainfall on the country’s coastlines. When completed in 2025, it will help assess which areas are most vulnerable, based on the predicted depth and duration of floods. “We have to look at this in a very dynamic way,” Grace Fu, minister for sustainability and the environment, said at a September event launching a new coast and flood protection institute. “Protecting us too much, you waste a lot of resources. If you build the coastal protection solution too low, then you will find that, several generations later, you’ll need to enhance it.”

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Government authorities are already considering storm surge barriers on Singapore’s waterways. The barriers would generally be open, so ships can travel to their destinations. But during a big storm, they would close, encircling the city’s industrial areas. Other possible measures: raising the height of current coastal reservoir dikes; tide gates, which block water; and more embankments, typically raised piles of earth. Singapore is also building a huge additional terminal at its airport on higher ground, 18 feet above average sea level. More than 6 miles of drainage are planned to keep runways clear of water.

Businesses are getting into the act, too. Real estate company City Developments Ltd. has built barriers and water-level sensors at the St. Regis Singapore hotel, Palais Renaissance shopping mall and Republic Plaza skyscraper. In the business district, Frasers Property’s 38-story tower has added floodgates. “More still needs to be done,” says David Fogarty, CBRE’s head of ESG consulting services for Singapore and Southeast Asia. “Companies are thinking about rising sea levels, but they aren’t acting fast enough.”

Enlisting nature

At the Sungei Buloh Wetland Reserve, the roots of mangrove trees have all kinds of configurations. They can look like a pencil, a bent knee or a stilt. The tropical trees flourish in salty tidal waters. Their thick aboveground roots and trunks break waves and trap sediment—forming a natural barrier to rising seas.

To protect shorelines properly, mangrove forests should sprawl for hundreds of yards. In neighboring Indonesia, they can even stretch for miles. In Singapore, mangroves can reduce storm wave heights by more than 75%. Mangrove forests also soak up to four times as much carbon as rainforests.

But mangroves alone aren’t enough. Singapore is studying whether it can combine the trees with other barriers, called revetments, often made of stone or concrete. Experiments involving combined mangrove-rock revetments are underway at Kranji Coastal Nature Park, near the wetland reserve, and Pulau Hantu, an island off the southern coast.

Singapore’s existing sea walls and revetments limit one possible solution, encouraging the growth of more mangrove habitat, says Daisuke Taira, a mangrove researcher at the National University of Singapore’s Centre for ­Nature-based Climate Solutions. The country should preserve the current habitat of tropical trees, and their protective roots, researchers say. But it will likely have to rely more on barriers and other feats of engineering. When it comes to cultivating mangroves to keep the seas at bay, Taira says, “Singapore is one of the most challenging places.”

Borrowing from the Dutch

On Pulau Tekong, an island northeast of Singapore, giant machinery whirs and clanks as workers stabilize soil and lay out a network of intricately designed drains and pumps. The equipment collects and channels rainwater into a pond. Excess can then be pumped into the ocean. This system, along with sea walls, enables Singapore to do something extraordinary: reclaim land that’s below sea level.

Singapore is taking a page from the Netherlands, a third of which is below sea level. The Dutch built sea walls beyond their coastline, creating new tracts of land they call polders. A bean-shaped plot of land on Pulau Tekong is the first polder in Singapore. At 3 square miles, it will add 1% to Singapore’s landmass once it’s completed at the end of 2024 and will be used for military training.

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Polders use less sand than the kind of reclamation Singapore has used in the past. That’s a huge advantage because it’s one of the world’s biggest importers of sand, which is expensive.

Singapore is adapting Dutch methods to the tropics. Its corner of the Pacific is calmer than the North Atlantic, so sea walls don’t need to be as high as in the Netherlands, according to JanJaap Brinkman, a director at Dutch water research institute Deltares, which is advising Singapore.

Still, Singapore has more intense rain, so its ponds, drainage canals and pumps are designed to cope with more water. Brinkman says the government is learning on its own and starting relatively small on Pulau Tekong: “Singapore wants to see if the technology is safe, and ensure everything is working well, before it takes the next step.”

—Lee, Xu and Kua reported this story from Bloomberg’s Singapore bureau.