Dec 2, 2019 7:00 AM

How Airports Are Protecting Themselves Against Rising Seas

Many of the nation's busiest airports are subject to increased flooding from climate change. So they're building seawalls and relocating sensitive equipment.

Sandbags line the checkin counter at Newark Airport

Next fall, San Francisco International Airport plans to begin environmental studies for its next big construction project. The $587 million project, targeted for completion in 2035, won’t produce another terminal, runway, or amenity for the airport’s 55 million annual passengers. It will be a seawall, an 8-mile-long bastion of steel and concrete. It will also be the centerpiece of SFO’s plan to protect itself from the steady rise of San Francisco Bay.

Since the 1980s, SFO has installed a variety of features to protect itself from the risk of flood associated with rising waters, including berms, concrete walls, and the kind of sheet piling construction projects use to keep water out of building sites. The new wall betrays a bolder ambition, to keep the airport’s facilities and four runways dry for the next half century or more. That means building to protect against 3 feet of sea level rise, the level anticipated by 2085. And while San Francisco International has one of the better-defined plans for warding off the water, it’s far from the only American airport facing this challenge.

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Rising tides may lift boats, but they can sink airplanes. According to the 2014 National Climate Assessment, 13 of the country’s 47 largest airports have at least one runway that’s vulnerable to moderate or high storm surge. Along with San Francisco and its across-the-bay buddy Oakland International, these include the New York area trio of Kennedy, LaGuardia, and Newark. Boston’s Logan and Philadelphia International are at risk, as are Washington, DC’s Reagan and Honolulu International. The waters pose a threat to airports in Fort Lauderdale, Florida, Miami, New Orleans, and San Juan, Puerto Rico. It’s not that the waters will come up and swallow these places the way an incoming tide swallows a sandcastle—at least not this century. Rather, the higher water levels will exacerbate the effects of storms, making floods more common and damaging.

The list of threatened airports is long because coastal areas make for good places to put planes: They tend to be flat and low-lying, and their bodies of water provide lots of open space for arriving and departing aircraft. But as climate change takes hold—spurred on by the emissions that jet aircraft pump into the atmosphere—that convenience has become a vulnerability. And though airports have long been aware of that shift, the pummeling that Superstorm Sandy dealt to New York City in 2012 made clear the severity of the problem. Water overtook LaGuardia’s runways and damaged electrical infrastructure, forcing a three-day closure that cost millions.

Like most problems posed by a shifting climate, the fixes are neither easy nor cheap. The obvious option is to keep the water out. That’s the goal of SFO's seawall. Oakland's airport plans to fortify and raise by 2 feet the 4.5-mile dike that separates its main runway and terminals from the bay. That should cover it until 2050, for $46 million.

Airports are packed with guts passengers rarely see or think about, none of which do well in floods. These include electrical systems, plumbing lines, telecoms, mechanics like air intakes, ventilation fans and ducts, medical and safety supplies, smoke and fire alarms, record storage, and hazardous materials such as jet fuel and chemicals. To protect such facilities, the Massachusetts Port Authority, which oversees Boston's Logan, issued a floodproofing design guide in 2014 that called for a mix of “dry” and “wet” approaches. Dry floodproofing means keeping the water out altogether, using things like flood barriers in doorways and staircases, and using aquarium glass that can hold back a wave of H₂O. The wet way allows more water in, but ensures that all vulnerable infrastructure is well above the point it will reach. For existing facilities, Massport set that point at 13.7 feet above sea level, projected to keep it dry until 2030. New facilities will have to meet the 2070 height of 17 feet.

The good news is that funding for such projects isn’t hard to come by. The Federal Aviation Administration, Federal Emergency Management Agency, and other agencies provide grants for airport improvements. In 2015, Governor Andrew Cuomo said New York had landed $28 million from the feds to protect LaGuardia by building new floodwalls and drainage systems, and improving its electrical systems. New York area airports have received a total of $150 million in federal funds to explore similar projects.

The bad news is that the predictions regarding sea level rise have only become more dire in recent years. San Francisco’s original plan was designed to handle 11 inches of sea level rise, per 2012 estimates, and would have cost about $50 million. Preparing instead for a 36-inch rise increased the cost tenfold. “It’s going to be an evolving battle,” says Patti Clark, a former airport manager who now teaches at Embry-Riddle College of Aeronautics. Airports must continually review their plans and revise them as necessary. They should focus on flexibility, she says, ensuring any flood mitigation strategies they develop can be adjusted once they’re underway or in place.

But even that’s no guarantee that an airport can stay above water. In a June 2018 report, the Regional Plan Association, a New York-based nonprofit research group, warned of the threats of sea level rise to the area’s airports. Kennedy, LaGuardia, and Newark would all be fine if they take action soon. But New Jersey’s Teterboro, which serves small aircraft and business jets, would be partially flooded by a 1-foot rise in sea level, and 3 feet would completely inundate it. “Over the next 20 to 30 years the airport will slowly start to lose its battle with sea level rise and will need to be replaced,” the report concluded. Its recommendation: Start phasing out Teterboro soon, move its flights to the bigger airports nearby, and make damn sure those can handle an all-too watery future.