Around the world, many airports, both large and small, are located along coasts, putting them at risk of coastal flooding. With sea levels anticipated to rise as a result of climate change, the flood risks faced by these airports are only expected to increase. In a recent journal article, researchers from England’s Newcastle University examined the extent to which the flood risk for individual coastal airports increases under various sea level rise scenarios. They estimate that by 2100, at least 10% of all existing air routes could be disrupted as a result of sea level rise, posing a systemic risk to the aviation industry.
Titled “Global analysis of sea level rise risk to airports,” the article appeared Dec. 31 in the online version of the journal Climate Risk Management. The article was written by Aaron Yesudian, a graduate student in Newcastle’s engineering college, and Richard Dawson, Ph.D., CEng, FICE, a professor of earth systems engineering at Newcastle’s engineering college.
Examining different scenarios
For their study, the researchers evaluated 1,238 coastal airports worldwide that are situated at elevations of less than 10 m above sea level. The researchers assigned each airport a level of existing flood protection based on data from the Flood Protection Standards database, known as FLOPROS. Developed by Dutch scientists, the global database lists the flood-return period and existing protection standards for given areas, typically at a national or state level.
Because of its large-scale nature, the data in the FLOPROS database is not a “perfect representation of the level of protection at individual airports,” Dawson says. For example, airport flood-protection systems that exceed (rather than just meet) the regulatory requirements are not fully accounted for in the database. That said, the data offer a “shared, consistent approach” for understanding flood risks for individual airports worldwide, he says.
For their study, the researchers examined the extent to which coastal airports would be subject to flooding under the following scenarios:
Stabilization of the warming of the global mean temperature at 1.5 degrees Celsius this century, leading to a median sea level rise by 2100 of 52 cm.
Stabilization of the warming of the global mean temperature at 2 C this century, leading to a median sea level rise of 63 cm.
A high-baseline emission scenario — known as the Representative Concentration Pathway 8.5, or RCP8.5 — in which greenhouse gas emissions continue to rise throughout the 21st century, leading to a median sea level rise of 86 cm.
A scenario known as RCP8.5+, a plausible worst-case scenario of Greenland and Antarctic ice melt in which sea level would rise by 1.8 m.
Flood risk and disrupted routes
As a means of quantifying the effects of flooding on individual airports, the researchers estimated the average number of routes from a given airport that would be disrupted annually by flooding at the various levels of sea level rise. This criterion was used because such data as the number of passengers and freight tonnage served is not publicly available for all airports, Dawson says. As such, disrupted routes offer a “good proxy for the economic losses from airport disruption,” he notes.
Currently, 269 airports are at risk of coastal flooding, the researchers found. Europe has the highest number of these (82); followed by Oceania (58); North America (51); and East Asia, Southeast Asia, and Russia (47), according to the article. Of the top 20 airports currently most at risk of disruption from flooding, 10 are in China. Bangkok’s Suvarnabhumi Airport topped the list of airports currently most at risk.
However, differences in flood protection lead to differing annual levels of risk around the world. For example, European airports in coastal floodplains currently have an average of 1.98 routes at risk of disruption because of flooding, while only 0.51 North American routes are at risk annually. By contrast, Oceania has 12.32 routes at risk, while 34.53 routes are at risk in East Asia, Southeast Asia, and Russia.
When future sea level rise is accounted for, the number of at-risk airports increases, as does the number of disrupted routes. For example, sea level rise associated with the 1.5-degree Celsius warming scenario is expected to result in 338 airports at risk of coastal flooding by 2100, potentially disrupting more than 860 routes. The latter figure represents approximately 10% of all routes worldwide, according to the article.
Under the 2-degree Celsius warming scenario, these numbers are expected to increase to 364 airports and more than 915 routes. Meanwhile, the RCP8.5 scenario would subject 413 airports to coastal flood risk, potentially disrupting approximately 1,114 routes. Finally, the RCP8.5+ scenario would put 572 airports at risk of flooding, possibly disrupting more than 3,580 routes, the article notes.
In all the above scenarios, airports in East Asia, Southeast Asia, and Russia would be expected to incur the most route disruptions despite having fewer airports at risk of coastal flooding compared with other regions. Under the worst-case scenario (RCP8.5+), three major U.S. airports — Louis Armstrong New Orleans International, LaGuardia in New York City, and Newark (New Jersey) Liberty International — are ranked in the top 10 of airports most at risk worldwide.
Ultimately, adapting airports to maintain their present level of risk in 2100 could cost up to $57 billion, according to the article. Such a level of spending is “modest in the context of global infrastructure expenditure,” the article states.
With the worst anticipated effects of sea level rise several decades away, airports have an opportunity to begin planning necessary improvements well in advance of when they will be needed, Dawson says. “By recognizing the risk now, it’s plenty of time for those airports to put in place long-term plans to ensure continued protection and management of flood risk in the face of rising sea levels,” he notes.
Ideally, airports and their stakeholders will incorporate such measures into their regularly scheduled maintenance and upgrades, Dawson says. “With planned management, they can weave (upgrades) into their long-term planning and budgeting without taking a huge hit,” he says. “That would be far more sensible than waiting for the next big flood to take out several facilities.”
That said, some locations will have a harder time than others paying for the necessary improvements. “The airports that will struggle the most are those in remote areas, and particularly those on small low-lying islands,” Dawson says. “There’s not many options for the airstrips to move because the whole island is at risk from sea level rise.”