Rising seas threaten world's airports
224 airports around the world are less than 3 meters above sea level

Sea levels are slowly rising with global warming, putting airports, harbors, power stations, oil storage and other key infrastructure at coastal areas at flood risk. How can we protect crucial infrastructures?

Cities around the world are being forced to adapt to a changing planet.

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“Climate change risks to cities, settlements and key infrastructure will rise rapidly in the mid- and long-term with further global warming, especially in places already exposed to high temperatures, along coastlines, or with high vulnerabilities,” the United Nations Intergovernmental Panel on Climate Change warned in a report published on Feb. 28.

Of the world’s 5,014 mid- or large-size airports, 753 – or about 15% – have an elevation of less than 10 meters, according to a Nikkei analysis based on data from OurAirports and other sources.

If sea levels rise 1 meter, 35 airports will be at sea level. A rise of 3 meters would essentially submerge 224 airports while a 7-meter rise would inundate 591.

Among the top 100 airports in terms of passenger numbers, 28 – nearly 30% – have an elevation of less than 10 meters. Amsterdam Airport Schiphol in the Netherlands is already below sea level. If the oceans rise 3 meters, five airports, including Suvarnabhumi in Thailand, will be below sea level. If there is a 7-meter rise, 19 more airports -- including John F. Kennedy in the U.S. and Shanghai Pudong in China – will be below sea level.

If the sea level rises 1 meter

Airports located at or below sea level

Schiphol (Netherlands)

Airports located less than 3 meters above sea level

Shanghai Pudong (China), Shanghai Hongqiao (China), Shenzhen Baoan (China), Suvarnabhumi (Thailand), Don Mueang (Thailand), Hamad (Qatar), John F. Kennedy (U.S.), San Francisco (U.S.), Miami (U.S.), Fort Lauderdale (U.S.), Barcelona (Spain), Fiumicino (Italy), Brisbane (Australia)

If the sea level rises 3 meters

Airports located at or below sea level

Shanghai Hongqiao (China), Suvarnabhumi (Thailand), Don Mueang (Thailand), Miami (U.S.), Fort Lauderdale (U.S.), Schiphol (Netherlands)

Airports located less than 3 meters above sea level

Shanghai Pudong (China), Shenzhen Baoan (China), Hamad (Qatar), John F. Kennedy (U.S.), Ronald Reagan (U.S.), San Francisco (U.S.), San Diego (U.S.), Newark (U.S.), Vancouver (Canada), Barcelona (Spain), Fiumicino (Italy), Copenhagen (Denmark), Brisbane (Australia)

If the sea level rises 7 meters

Airports located at or below sea level

Shanghai Pudong (China), Shanghai Hongqiao (China), Shenzhen Baoan (China), Hangzhou Xiaoshan (China), Incheon (South Korea), Changi (Singapore), Suvarnabhumi (Thailand), Don Muang (Thailand), Hamad (Qatar) John F. Kennedy (U.S.), Ronald Reagan (U.S.), San Francisco (U.S.), Miami (U.S.), Fort Lauderdale (U.S.), San Diego (U.S.), LaGuardia (U.S.), Newark (U.S.), Logan (U.S.), Vancouver (Canada), Schiphol (Netherlands), Barcelona (Spain), Fiumicino (Italy), Copenhagen (Denmark), Sydney (Australia), Brisbane (Australia)

Airports located less than 3 meters above sea level

Kansai (Japan), Hong Kong (Hong Kong), Palma de Mallorca (Spain)

According to a report released by the United Nations Intergovernmental Panel on Climate Change in August 2021, global sea levels have risen by about 20 cm since 1900. If greenhouse gases continue to be emitted at or near current levels, sea levels are projected to rise by about 1 meter by 2100 and 2 to 7 meters by 2300.
Storm surge associated with hurricanes and typhoons can reach 10 meters, and as sea levels rise, so does the risk of flooding at airports in low-lying areas.

LaGuardia Airport, which is about 10 km east of Times Square in Manhattan, New York City, is a hub for U.S. domestic flights and was used by 46 million passengers in 2019 before the COVID-19 pandemic. The airport faces the East River in the Straits, and its two runways are only about four meters above sea level.

In October 2012,
Hurricane Sandy hit the U.S. East Coast

In October 2012, Hurricane Sandy smashed into the East Coast of the U.S., with a massive storm surge hitting New York City. Almost the whole of LaGuardia Airport was flooded, including its runways and terminals, closing the site for three days.

The airport was upgraded with flood control measures after the disaster.

In the aftermath of Sandy, the Port Authority of New York and New Jersey (PANYNJ), which operates the airport, spent a total of $37 million improving flood protection measures.

Note: Compiled by Nikkei using public documents from the Federal Aviation Administration (FAA)

Note: Compiled by Nikkei using public documents from the Federal Aviation Administration (FAA)

Dikes

The airport is built on reclaimed land and has perimeter dikes on most parts facing the ocean. The dikes protecting the substation on the west side of the airport were built after Sandy hit.

Drainage pump

Of the five drainage pump facilities, the one on the east side was elevated and a new emergency power supply was added in preparation for flooding. Other electrical facilities were also enclosed with walls and some were raised.

New terminal

The airport is undergoing a nine-year redevelopment that will run until 2024. Its new terminal is equipped with water-resistant walls and doors to protect it from Sandy-level flooding. An emergency power supply has also been boosted.

According to public documents from PANYNJ, current measures are based on the assumption that sea levels will rise by about 40 cm by 2050, 70 cm by 2080 and 90 cm by 2100. A PANYNJ spokesperson said, "The agency continues to study resiliency best practices to account for sea level rises through the end of the century and beyond."

Completion image of LaGuardia Airport that is under redevelopment (Photo courtesy of PANYNJ)

Singapore's Changi Airport is the largest air hub in Southeast Asia, with 68.3 million passengers using it in 2019. According to operator Changi Airport Group and other companies, the site's Runway 1, which was built when the airport opened in 1981, is 4 meters above sea level, while Runway 2 is at 4.5 meters.

Secure elevation in anticipation of sea level rise

Note: Compiled by Nikkei using public documents from the Civil Aviation Authority of Singapore

In 2011, Singapore's government lifted the required minimum height above sea level for new development sites from 3 meters to 4 meters, based on the assumption that ocean levels will rise by up to 76 cm by 2100. In response, Runway 3, which went into service in 2020, was designed to be 4.8 meters above sea level, while Terminal 5, currently being developed, is set to be 5.5 meters above sea level.

Newer runways are higher

Note: Compiled by Nikkei based on hearings and interviews with the airport operator and others.The elevation of the airport registered with OurAirports is 6.7 meters.

Changi Airport has also continued to strengthen other flood control measures, and in 2016 raised the embankment road north of the site by 80 cm over a 1-km stretch. It also installed a sensor system in 2021 to automatically monitor the condition of runway drains.

Singapore has a strong sense of urgency about rising oceans as about 30% of its land area is less than 5 meters above sea level. Gerald Ng, vice president of environment and sustainability at Changi Airport Group, said, "Changi Airport is committed to working closely with the Singapore government on climate resilient measures, to ensure the sustainable development of the airport."

Amsterdam Airport Schiphol in the Netherlands was built in 1916 at the bottom of a drained lake. It is about 20 km from the sea, but its six runways, surrounded by lowlands, are in areas 4 meters below sea level.

The never-ending battle against water

Note: Compiled by Nikkei from public documents of LVNL, Air Traffic Control the Netherlands

In areas at or below sea level, a major challenge is how to drain water that accumulates while preventing water from flowing in from outside. Since 2018, Schiphol Airport has been phasing in a new drainage system that will store as much water as possible inside the site to prevent backflow.

Store water on site to prevent backflow

Note: Compiled by Nikkei using documents from Royal Schiphol Group

The drainage ditches that rainwater flows into are 80 cm in diameter, and when the drains are about to overflow, water will be stored in pools set up underground. Gaps in the foundation of the runway will also be used for water storage.

Delay drainage off the site

Note: Compiled by Nikkei using documents from Royal Schiphol Group

The total length of the waterway network is 450 km. The multilayered system enhances water storage functions within the site and creates a time lag for delaying drainage until the water level at a reservoir outside the site drops.

Schiphol Airport has been ahead of the fight against water that airports around the world will face in the future. "We also assess potential consequences of impactful events and gradual changes in climate and take measures to minimise and prevent potential climate-related risks," a report compiled by the airport stresses.

Video posted by Royal Schiphol Group on YouTube

Defense construction could cost $57bn worldwide

Total cost of countermeasures for airports at risk of sea level rise
Rise of temperature less than 1.5 degrees
Rise of temperature less than 2 degrees
Without measures to prevent global warmingWithout measures to prevent global warming and assuming high rise in sea level
Defense construction33.034.738.956.8
Defense maintenance0.70.70.81.1
Raising elevation26.527.831.347.4

Estimate by a research group from the University of Newcastle in the U.K. Countermeasure costs are upper limit. Numbers in billions of USD.

In a paper published in 2021, a research group from the University of Newcastle in the U.K. identified 269 airports currently at risk of flooding during high tides because of rising sea levels, and this could disrupt aviation routes. If greenhouse gases continue to be emitted at present levels, the number of airports at risk would increase to 572 by 2100, according to the survey.

To keep airport risk levels constant, either dikes would have to be built or the sites raised. The group put the worldwide cost of building dikes at between $39 billion and $57 billion by 2100.

One of the authors of the paper, Professor Richard Dawson, said: “The cost of adaptation will be modest in the context of global infrastructure expenditure. However, in some locations the rate of sea level rise, limited economic resources or space for alternative locations will make some airports unviable.”

Threats loom over airports in Japan

Kansai International Airport (KIX) was flooded by a typhoon in September 2018. (Photo courtesy of Japan's Ministry of Land, Infrastructure, Transport and Tourism)

Typhoon No. 21 hit the Kinki region around Osaka, Kyoto and Kobe in September 2018. The runways and terminals at KIX, which is located on a man-made island, were flooded by exceptionally high waves.

(Video courtesy of Japan's Ministry of Land, Infrastructure, Transport and Tourism)

54 billion yen ($460m) invested in countermeasures after the KIX typhoon inundation

Post-typhoon countermeasures at KIX include raising the seawall (Photo courtesy of Kansai Airports Group)

After the typhoon damage, the KIX seawall was raised by up to 2.7 meters, and the runway is being raised by 16 to 42 centimeters. The total cost of the KIX countermeasures is about 54 billion yen ($460m).
The land KIX sits on continues to sink by 6 to 7 centimeters each year, so any future rise in sea level would force KIX to take further measures.

About 20% of major airports in Japan are less than 7 meters above sea level
Elevation of major domestic airports in Japan

Note: Compiled by Nikkei from data by OurAirports.

An analysis of 89 airports in Japan, based on data from OurAirports and other sources, showed that 25 airports, including KIX and Fukuoka, are 10 meters or less above sea level. 17 airports, including Central Japan International Airport in Aichi Prefecture and Naha in Okinawa Prefecture, were less than 7 meters above sea level, and two other airports were less than 3 meters.

The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) is strengthening disaster prevention measures at 23 airports that serve as regional hubs, but "at this stage, we are not taking into account the impact of sea level rise due to climate change," said an official at the ministry's Civil Aviation Bureau.

Scenarios for sea level rises vary according to how much human intervention in global might be possible

Global average sea level change compared with 1900

Note: Compiled by Nikkei based on the Sixth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC).

The IPCC report warns that it is almost certain sea levels will continue to rise during the 21st century. Even if greenhouse gas emissions are curbed, and the temperature rise is limited to 1.5 degrees Celsius by the end of the century, sea levels will rise by 28 to 55 centimeters. The IPCC predicts that sea levels will continue to rise thereafter.

Many of the world's major cities are located along coasts, so in addition to airports other important infrastructure is also vulnerable to flooding, including harbors, oil tanks, power plants and factories. Even if exact scenarios cannot be predicted for 100 or 200 years in the future, experts say it is time to start moving.

Research and analysis methods:

From OurAirports' open data (Feb. 14, 2022), we obtained location and elevation information for 5,014 airports of medium and larger size, and examined the impact of a rise of 1, 3 or 7 meters in sea level from present levels. The number of passengers at airports was provided by Cirium, a U.K.-based aviation data company, and was for 2019 before the COVID-19 pandemic struck. Maps of LaGuardia, Changi and Schiphol airports and surrounding areas were created using NASA's Shuttle Radar Topography Mission from a survey in 2000.