Before the Flood

In the early morning of August 8, 2007, at the cusp of New York’s epic rush hour, the grey sky over Gotham burst open in a fearsome downpour, the third major storm in seven months. Within a few hours, the flooding was so severe that the Metropolitan Transportation Authority (mta) cancelled all Metro-North trains, the city’s link to suburbs across the state and into Connecticut. In addition, all twenty-four of the mta’s subway lines were either delayed, or suspended for up to eight hours. Meanwhile, the storm whipped up an exceedingly rare category 2 tornado that slammed into the southwest shoreline of Brooklyn. With winds reaching 217 kilometres an hour, the twister shredded roofs, wrapped street signs around their poles, and uprooted trees. When the so-called 8/8 deluge subsided, it had contributed to one death, caused untold millions of dollars of damage, and disrupted the commutes of 2.5 million crabby New Yorkers.

Elizabeth Yeampierre was one of the lucky ones, given that the tornado hit a mere thirty blocks from her office in a narrow row house in the waterfront Brooklyn neighbourhood of Sunset Park. An energetic civil rights lawyer with unruly black hair, Yeampierre heads uprose, an ngo founded in the mid-1960s to support Sunset Park’s disenfranchised Puerto Rican community. Lately, uprose has focused on engaging this diverse blue-collar precinct in environmental issues, spearheading campaigns to block the construction of a shoreline power plant and push for more green space on the water. Yeampierre added climate change to her agenda last summer, but it’s a tough sell in an area where many residents hold down two or three jobs just to get by. “People go through their lives passively, not thinking about what all this means,” she observes. The 8/8 deluge, however, left little doubt of Sunset Park’s vulnerability to the vicious storms experts have associated with global warming. “You know,” she says, “that was a wake-up call.”

Indeed, storms like 8/8 are only the tip of the proverbial iceberg. As rising global temperatures melt polar ice sheets, sea levels rise as well. At the same time, many scientists believe warmer oceans are increasing the frequency and violence of hurricanes. When combined with high tides and elevated sea levels, these conditions can produce fearsome walls of water that pound shorelines. In coming years, this three-pronged threat could cripple coastal regions that haven’t protected themselves against storm surges and flash floods.

In late 2006, Sir Nicholas Stern, an adviser to the British government, released a study documenting the accruing economic impact of climate change. The most comprehensive of several such studies, the Stern review warned that by the 2080s rising sea levels could be dislocating tens of millions of urbanites annually in Asia, North America, Europe, and Australia. Besides the incalculable human toll, vital infrastructure — subways, power plants, ports, airports, water treatment facilities — will become ever more vulnerable to flooding. As Stern noted, Hurricane Katrina caused more than 1,300 deaths, displaced a million Americans, and inflicted $125 billion (US) in damage, only 40 percent of which was insured.

“New Orleans weighs heavily on our minds,” Yeampierre says. And no wonder. New York is surrounded by water: the Atlantic, Long Island Sound, and the Hudson, Harlem, and East rivers. The city has some 2,000 bridges and tunnels, and 10 percent of its land mass, including much of Lower Manhattan, the city’s three airports, and the vast docklands in Jersey City, is less than three metres above sea level — for now, that is.

Of particular concern is the impact on infrastructure situated within the flood zone, including fourteen water and sewage treatment plants. Hundreds of combined sewer outflows embedded in seawalls line the city’s extensive shoreline, and if water levels spike, these pipes could be abruptly inundated, resulting in a massive flow of contaminated backwash into countless basements.

New York’s transit infrastructure is even more at risk, because so much of it is already below sea level. Even on a sunny day, the mta pumps more than 49 million litres of water out of the subways (enough to fill nineteen Olympic pools), but a panel of experts recruited by the mta after 8/8 determined that those mechanical systems had been overwhelmed — and not for the first time. They recommended elevating the subway’s sidewalk grates, building step-up curbs at station entrances, and installing more pumps. But, as they also pointedly warned, “Flooding cannot be solved by narrow engineering solutions based solely on past experience.”

Malcolm Bowman, an oceanographer at the State University of New York’s Stony Brook campus on Long Island, isn’t interested in “narrow engineering solutions.” A native New Zealander with the white beard and twinkling eyes of an off-season Santa, Bowman and collaborator Douglas Hill have spent seven years shopping around a proposal to build enormous retractable storm surge barriers in three locations around New York, including one straddling the Verrazano Narrows, and another at Throgs Neck, where Long Island Sound meets the East River. Such barriers, rising fifteen metres above sea level, would effectively wall off New York Harbor if a major hurricane sent tsunami-like waves t