The problem with building airports near sea level
As a powerful typhoon tore through Japan this week, travelers at Kansai International Airport looked out on a terrifying void. Where there should have seen the runway, they saw only the sea.
They also saw what could be a perilous future for low-lying airports around the world, increasingly vulnerable to the rising sea levels and more extreme storms brought about by climate change. A quarter of the world’s 100 busiest airports are less than 10 metres, or 32 feet, above sea level, according to an analysis of data from Airports Council International and OpenFlights.
Twelve of those airports — including hubs in Shanghai, Rome, San Francisco and New York — are less than 5 metres above sea level.
“We were trapped,” said Takayuki Kobata, a web entrepreneur who had hoped to board a Honolulu-bound plane from Kansai, a vast airport on an artificial island near Osaka. “We just had to wait for the storm to blow over.”
He spent close to 36 hours trying to find a way off the flooded island, a task further complicated by a ship that ripped from its moorings and crashed into the bridge from the airport to Osaka, severely damaging the roadway.
The threat from rising waters comes as a reckoning for an industry that ranks among the major contributors to climate change. Air travel accounts for about 3 per cent of greenhouse gas emissions worldwide, but is one of the fastest-growing emissions sources. Given current trends, emissions from international air travel will triple by 2050, the International Civil Aviation Organization has predicted.
As the aviation industry grapples with its carbon footprint, it has also started to feel the effects of global warming. Extreme heat can ground planes because hotter, thinner air makes achieving lift difficult. A changing climate can also increase turbulence.
Low-lying areas along the water have long been seen as ideal sites for building new runways and terminals, because there are fewer obstacles for the planes during takeoff and landing, and less potential for noise complaints. But coasts also provide few natural protections against flooding or high winds.
All told, extreme weather and rising sea levels today pose one of the most urgent threats to many of the world’s busiest airports, which often weren’t designed with global warming in mind.
“We know that there are going to be impacts. And we expect those impacts to become serious,” said Michael Rossell, deputy director-general at Airports Council International, a group representing airports from across the world. “Recognizing the problem is the first step, and recognizing the severity is the second. The third is: what can we do about it?”
Many airports have started to bolster their defences.
St. Paul Downtown Airport in Minnesota, which has been frequently flooded by the Mississippi, now has a portable flood wall that can be erected if the river starts to overflow. With the help of a US$28-million federal grant, La Guardia Airport in New York is adding a flood wall, rainwater pumps and a new drainage system for the airfield, as well as upgrading its emergency electrical substations and generators.
Kansai airport, which serves the bustling cities of Osaka, Kyoto and Kobe and handled almost 28 million travelers last year, faces an additional predicament. A feat of modern engineering, Kansai sits on an island five kilometres offshore that was built over the course of a decade from two mountains’ worth of gravel and sand. The airport, which opened in 1994, was built in Osaka Bay partly to minimize noise problems but also to avoid the violent protests over land rights that are the legacy of older airports in Japan, like Narita, which serves Tokyo.
Signs of trouble came early. Engineers had expected the island to sink, on average, less than 30 centimetres a year over 50 years after the start of construction as the seabed settled under the airport’s weight. But the island sank about 10 metres in its first seven years and has continued to descend, now losing 13 metres in elevation at the last measurement.
Engineers had boasted that the walls were tall enough to withstand storms as strong as a major 1961 typhoon that caused the sea to surge almost three metres. But Typhoon Jebi, which killed 11 as it tore through west Japan this week, generated a storm surge that reached almost 3.5 metres, a record for Osaka Bay. Waves crashed over the airport’s seawalls and swamped its pumps, officials said.
It remains unclear when the battered airport will fully reopen. Kansai was to reopen Friday to domestic flights using the shorter of its two runways, which escaped the worst of the damage.
At a televised news conference, Yoshiyuki Yamaya, the president of the airport’s operator, was contrite. “We geared up for a typhoon, but the typhoon was far stronger than we had expected,” he said. “We were too optimistic.”