News•June 18, 2013

U.S. Airports Face Increasing Threat From Rising Seas

When Hurricane Sandy struck New York City on October 29, 2012, the dark waters of Flushing Bay poured over the edges of LaGuardia Airport, flooding parts of the facility’s 7,000-foot long east-west runway, and damaging lighting and navigation systems. The floodwaters created an eerie image of jetways ending in water, as if they had been converted into boat ramps.

This was not the first time that LaGuardia suffered major flooding during a storm, nor will it be the last. Due to climate change-related sea level rise, LaGuardia and other coastal hubs throughout the U.S. face a growing risk of flooding during even modest storms.

What LaGuardia Airport could look like at high tide with 5 feet of sea level rise, an amount that could occur by 2100, according to some estimates.
Click on the image to enlarge. Credit: Nickolay Lamm/StorageFront interpretation of Climate Central data.

A draft federal assessment of climate change impacts, which was released on Jan. 11, named a dozen major U.S. airports as being particularly vulnerable to sea level rise-related flooding risks, including all three of the major New York-area airports. And just last week, a new report found that the New York metropolitan area may face a greater amount of sea level rise during the next several decades than was anticipated just a few years ago.

The region's two other major airports also experienced storm-surge flooding during Hurricane Sandy, albeit to a lesser degree. John F. Kennedy International Airport saw flooding from Jamaica Bay, and Newark (N.J.) International Airport was hit by the storm surge that coursed through New York Harbor and into Newark Bay, flooding the eastern sections of the busy international gateway, and parts of the neighboring port, where waters reached 4 feet above ground level.

All three hubs closed on Oct. 28, before the storm hit, causing a ripple effect of tens of thousands of flight cancellations around the world. Newark and JFK Airports were able to resume limited service on Oct. 31, while LaGuardia was the last to reopen at a reduced capacity a day later. According to FlightStats.com, more than 20,000 flights nationwide were canceled due to Hurricane Sandy with roughly half of those cancellations coming from the New York-area airports.

U.S. Airports Most Vulerable
to Sea Level Rise

San Francisco Int'l (SFO)
Oakland International (OAK)
Honolulu International (HNL)
New Orleans Louis Armstrong Int'l (MSY)
Tampa International (TPA)
Miami Int'l (MIA)
Ft. Lauderdale Int'l (FLL)
Ronald Reagan Washington National (DCA)
Newark Liberty Int'l (EWR)
LaGuardia (LGA)
Philadelphia Int'l (PHL)
John F. Kennedy Int'l (JFK)

The trio of airports serve more passengers annually than any other metropolitan area in the world, other than London. Passenger traffic at the Port Authority of New York and New Jersey's four commercial airports — which includes the underutilized Stewart International Airport in Orange County, N.Y. — totaled 109.4 million in 2012. LaGuardia alone accounted for 25.7 million passengers during the year, with more than 1,000 daily landings and takeoffs, according to Port Authority figures.

The New York area's high-capacity airports may have been the first to get hit, but Hurricane Sandy should serve as a wakeup call to officials in charge of other low-lying airports across the country, since the latest climate science shows coastal airports face a growing danger from storm-surge impacts such as sea levels rise. More flooding will cause more delays, potentially costing billions of dollars in the years ahead from lost revenue and storm cleanup operations. The impact of weather-related delays on air travel already costs more than $4 billion annually.

The threat isn't that sea level rise will gradually breach the defenses surrounding each airport. Instead, at least during the next few decades, scientists say that sea level rise will be more of an enabler of storm-surge flooding, making it easier for even minor storms to produce more damaging surges and flooding. And when powerful storms hit, the threat is multiplied since they likely will produce unprecedented surges, much as Hurricane Sandy did in New York.

According to the draft National Climate Assessment, 12 of the nation’s largest airports have at least one runway with an elevation within 12 feet of current sea levels. In addition to the three airports in and around New York, the other vulnerable airfields listed are in Philadelphia, Washington, D.C., Miami, San Francisco, Honolulu, New Orleans, Tampa, Ft. Lauderdale and Oakland.

Those airports face critical challenges ahead, beginning with conducting risk assessments for long-lasting infrastructure, such as new terminals, runways, and maintenance facilities. Planners are studying options to better protect low-lying runways and airport buildings, such as navigation systems to allow aircraft to land in low visibility, and hardening or raising tank farms for storing aviation fuel.

Some, such as the managers of New York City's airports as well as San Fransisco and Oakland International Airports, have taken initial steps to assess their vulnerabilities, often in association with broader regional studies. Most, though, have not yet begun that work, putting them behind the curve.

The risk assessments that have been carried out so far are sobering, and once again, LaGuardia Airport is front and center.

One of the reports released on June 11 in conjunction with New York City Mayor Michael Bloomberg's $20 billion city-wide climate resilience proposal found that for LaGuardia Airport, at least, Sandy was not a worst-case scenario. The storm struck at low-tide along the western part of Long Island Sound, while it was high tide along the New Jersey coast and in other parts of New York City. LaGuardia flooded to a level of about 14 feet above Mean Lower Low Water, or about 9 feet above ground level.

A computer-model simulation from the Stevens Institute of Technology in Hoboken, N.J., found that had the storm hit at LaGuardia’s high tide, which was just nine hours earlier, the floodwaters would have reached a height of up to 12 feet above ground level. That most likely would have breached the terminal buildings, leading to a longer and more expensive shutdown of the facility after the storm subsided.

Futhermore, a new analysis from the New York City Panel on Climate Change found that sea level in New York City may increase by as much as 11 inches by the 2020s, and more than 2.5 feet by the 2050s. That would dramatically boost coastal flooding risks, and render LaGuardia’s current levees useless against even minor storms.

“More and more of the City's airport infrastructure will be at risk as storm surges will move from flooding outlying runways to threatening the terminal buildings,” said a transportation sector breakdown accompanying the report.

If sea level rise matches the high-end estimate of 31 inches by the 2050s, then today's 1-in-100 year flood, which has a 1 percent chance of occurring in any given year, may occur about five times more often.

While much of JFK Airport is outside of the city’s updated 100-year flood zone, as sea levels rise that is likely to change, the panel's report showed.

Since 1900, relative sea level has already risen by about 13 inches in New York City, due to manmade climate change and land-elevation shifts.

Climate studies examining Newark Airport have been more limited, since the climate assessments conducted by New York City have only focused on airports within its jurisdiction. The Port Authority, however, has found that Newark is also going to be at greater risk of storm-surge flooding as seas rise, but it is not considered to be as imperiled as LaGuardia. A 2012 New York State Climate Assessment also found that Newark is at slightly greater risk of flooding in severe storms compared to JFK.

Klaus Jacob, an expert in natural disasters at Columbia University and an advisor to New York state as well as the city, said that in addition to considering the impacts of sea level rise on the airport grounds, officials also need to take into account the networks of access roads and public transportation systems that transport airport workers and passengers to and from the facilities.

For example, Jacob said that although JFK Airport itself has a lower risk of flooding in today's typical storms compared to LaGuardia, its access roads could flood more easily from heavy rains during storm situations, potentially leading to situations where passengers and airport workers are cut off from the airport.

“While the airport itself may not be jeopardized, the access to it may be jeopardized,” Jacob said in an interview. “The Federal Aviation Administration may not take note of that, but in terms of operations it may cause significant problems.”

On the opposite side of the country, there have been several studies looking at transportation infrastructure in the San Francisco Bay region, home to two major airports on the federal government's “most vulnerable” list: San Francisco International and Oakland International Airport.

According to one study published by the Adapting to Rising Tides Project, funded by the San Francisco Bay Conservation and Development Commission and the National Oceanic and Atmospheric Administration's Coastal Services Center, general aviation facilities and runways at Oakland International Airport are likely to be inundated by new daily high tides with just 16 inches of sea level rise, which is within the range of most mid-century projections.

During a storm event, the airport could see flooding at a height of between 1 to 7 feet above ground level at various locations around the airport, including flooding of the longest runway, which is used by most jetliners. In addition, storm events coming on top of the 16 inches of sea level rise could render the main airport access roads impassable, the report found.

With 55 inches of sea level rise, which some studies project could occur by 2100 depending on how quickly the polar ice caps melt, the entire airport would be exposed to flooding during the daily high tide, the report found. That scenario would render the airport unusable on a regular basis unless new flood protection measures were in place.

Oakland International and San Francisco International Airport — the 7th-largest U.S. airport by passenger volume — were both built on land reclaimed from wetlands, and are about 10 feet above the current local sea level.

Climate change acts as a storm-surge risk magnifier in other locations, too, and not just in New York and the San Francisco Bay region. For example, Climate Central research shows that there is a greater than 30 percent chance that the water level will exceed 8 feet above the average local high-tide line at least once by 2030 in Washington, D.C., which would flood parts of Washington Ronald Reagan National Airport. And in Tampa, which is long overdue for a major hurricane strike, a Climate Central report says that there is a 40 percent chance that the water level, including the effects of a storm surge plus sea level rise, will top 5 feet above the average local high tide line at least once by 2030. That would flood part of Tampa-St. Petersburg International Airport, in addition to MacDill Air Force Base, home to the U.S. Central Command, which oversees U.S. military operations in the Middle East.

Solutions

Girding an airport against the threat of a damaging surge is not as easy as simply building a tall sea wall, since jetliners would have to be able to clear such a wall or levee when landing or taking off, Jacob said. One possible solution could be for the runways to be raised or partially elevated, in combination with the construction of a dike and levee system.

Jacob, who led part of a New York State sponsored assessment of sea level rise that was released in 2012, said he is unaware of any national or local strategic planning efforts underway by airport management agencies or regulators to prepare for sea level rise and increased risks of flooding, indicating that most of this work is just beginning to get underway in an ad hoc fashion.

Multiple phone calls and emails to the Port Authority of New York and New Jersey, which operates New York’s airports, went unreturned. However, Port Authority documents indicate that the agency is aware of the risk posed by sea level rise, and is increasingly incorporating that into their planning procedures and existing sustainability policy.

Mayor Bloomberg's climate resilience plan includes working with non-city agencies such as the Port Authority to ensure they are including climate change-related threats, including sea level rise, into their capital projects.

The federal Transportation Research Board has also urged airport managers, such as the Port Authority, to include climate-change adaptation in long-term planning, given the long lifespan of infrastructure built today.

There are a handful of airports here and abroad providing inspiration. San Francisco airport officials have been discussing the possibility of extending the airport’s runways onto floating platforms to increase runway length. That may have an added benefit of allowing the runways to rise with the sea level. In addition, a partial seawall and planned levees around San Francisco International Airport are expected to give that airport additional protection during the next couple of decades, depending on the rate and extent of sea level rise.

In St. Paul, Minn., the airport has suffered from frequent flooding from the Mississippi River, having been inundated three times during the past 15 years. To prevent the recurrence of such flooding, the airport installed a modular floodwall, which can be easily added to when floods threaten. A similar modular system is planned for protecting the Lower East Side of Manhattan from flooding, and could be constructed low enough to avoid interfering with aircraft takeoffs and landings. Such a system, also known as an integrated flood-protection system, would function much like building blocks, with some permanent structures installed and other temporary measures that could be added before a storm strikes.

Other airports that have incorporated flood-protection measures include Raratonga Airport in the Cook Islands, which installed a wave-protection barrier, and Brisbane International Airport in Queensland, Australia, which uses a combination of strategies, including pumps and strategically elevated land.

Whatever the solutions may be, one thing is clear: the ocean increasingly wants to be another passenger coming into low-lying coastal airports, and it will be up to this generation of engineers and airport managers to keep the water out.