The Weather of the Future: Heat Waves, Extreme Storms, and Other Scenes from a Climate-Changed Planet - Heidi Cullen (2010)

Part II. The Weather of the Future

Chapter 11. New York, New York

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New Year’s 2000 is one of the few moments in my life that I remember with great precision. I was standing on the corner of Fifty-Ninth Street and Columbus Avenue, freezing cold but happy to have company. My roommate had decided, uncharacteristically, that she was going to Times Square with some friends, and so I tagged along not wanting to be home alone in the apartment. It was almost midnight, so Fifty-Ninth Street was as close as we could get to Times Square. Despite frigid temperatures and months of media hype with dire predictions of power outages, bank runs, and other random catastrophes, there we all were. Hundreds of thousands of people from all over the world, ready to hug a stranger and ring in the New Year. As always, there was a sense that the New Year—in this case, it was also celebrated as the start of a new millennium—held the possibility of something better. And as far as I could tell, the competing sense that we might also witness human civilization crushed by a little bug was not lost on anyone.

That bug, of course, was the Y2K bug, the millenium bug. It was nothing more and nothing less than a computer bug resulting from the practice in early computer program design of representing the year with two digits. In fact, the term Y2K itself was born out of a good programmer’s relentless pursuit of efficiency. David Eddy, one of an army of programmers who worked on fixing the problem is credited with coining this term. He says he coined it on June 12, 1995,1 in an absentminded e-mail. “Being a good programmer,” he explains, “I’m a minimalist typist. And Y2K was simply 60 percent less effort/cheaper to type than year 2000.” Funny the way good intentions can come back to haunt us.

Actually, Y2K was wrapped up in something much bigger. “Y2K coincided with the end of the millennium, so it became somewhat of a Rorschach blot for our collective anxiety about the future. The greater the number of 0s in a year, the more we freak out,” explains Paul Saffo, a technology forecaster based in Silicon Valley who was among the first to push businesses to take Y2K seriously. He adds, “Y2K tapped into some pretty apocalyptic stuff. And in that sense I think it has some similarities with climate change.” Saffo is a consulting professor in the School of Engineering at Stanford University, where he teaches forecasting and the impact of technological change on the future. “Like Y2K, climate change is a technology problem that resonates with millennial anxieties.” I guess that would make climate change Y2K 2.0.

Still, there are some important differences. Government and business spent on the order of $100 billion dollars fixing Y2K, but the problem of climate change is a lot bigger and a lot harder to solve. “And ultimately, the Y2K story ends happily with a bunch of geeks saving the world from a stupid problem the geeks themselves created,” Saffo says. He thinks it will take a lot more than an army of geeks to fix the climate bug. And, of course, it’s not clear that the climate story will have a happy ending.

As a technology forecaster, Saffo helped persuade the business community to get to work quickly on Y2K. “Actually, it was pretty simple. I told them, ‘This is not hype. You can either fix the bug now, or you can wait until the last minute. But the longer you wait, the more expensive it will be to fix and the tougher it will be to hire people to fix it,’” Saffo explains. By then, businesses had already been running their own tests. And the outcome of the tests, which consisted of nothing more complicated than advancing their computer clocks out in time to the year 2000, suggested that Y2K was indeed a problem. When the clocks got to the year 2000, their computers stopped working. That’s what you might call a straightforward modeling experiment.

Even so, some businesses underreacted to Y2K at first, and then, just as Saffo had warned, they spent more money than they should have scrambling to fix the bug in their software. “I liked to use the sailboat analogy,” Saffo explains. “I’d say, ‘Imagine you’ve got a sailboat and you need to sail around an island. You can start to circle when you’re still a mile from shore and it will be easy. But if you wait until you’re only 100 meters away, there will be rocks and reefs. There will be a lot more drama.’”

But ultimately, the business sector wasn’t worried about drama so much as it was lured by potential opportunity.

“What really persuaded them in the end,” Saffo says, “was that we presented Y2K as an opportunity. We said, ‘Don’t just solve the Y2K problem; use this as an opportunity to improve your business.’” I guess in the end, we all live in the hope of a better future. The problem with climate change is that it presents a set of different futures and forces us to choose one: continue “business as usual” and live on a hot planet with rising seas or change course and rebuild our energy and transportation infrastructure. Either way, we will have to pay. And either way, Saffo’s sailboat analogy still applies.

When you’re talking about the future impact of climate change on New York City, Saffo’s sailboat analogy requires some modification: just pretend you’re on the island instead of in the sailboat. But you’re not in one of the buildings that make up the city’s famous skyline or in one of the yellow cabs that snarl traffic in the streets and avenues. Instead, you’re in a rather unassuming building above a place called Tom’s Restaurant.

I am convinced that being a scientist in New York City is a very special experience, because New York is an anti–ivory tower. Alternate side of the street parking forces the scientists who work at the Goddard Institute for Space Studies (GISS) to dash out of seminars and move their cars: parking tickets pile up if these scientists don’t pay attention to the real world. And the ground floor of GISS, one of the most important climate modeling centers in the world, is home to Tom’s Restaurant, a greasy spoon and Columbia University hangout made famous by the television show Seinfeld. I took classes at GISS as a grad student, and I found that the smell of french fries permeates the entire building. I don’t know how GISS scientists can get anything done.

It’s in this setting that Cynthia Rosenzweig works. Rosenzweig, a senior research scientist who heads up the Climate Impacts Group at GISS, hopes Americans can be convinced that, as with Y2K, fixing the climate bug is an opportunity to be seized sooner rather than later. And she’s spent her career proving that climate change is not hype.

Rosenzweig came to GISS as a young graduate student to work on agriculture in the early 1980s. “I arrived at a time when GISS was developing some of the first global climate model projections. Jim was the director,” she says. Jim is James Hansen, a well-known climate scientist and an outspoken advocate of reducing emissions. Hansen is still the director of GISS, which still has its headquarters in a nondescript building on the corner of 112th Street and Broadway.

Rosenzweig’s graduate work was in agronomy, and perhaps because she entered the climate community as somewhat of an outsider, she has a talent for connecting the mathematicians, atmospheric scientists, and physicists who know the climate change projections with the economists, policy makers, and engineers who have to figure out what to do about this issue. Rosenzweig has come up with a way to study the messy business of climate impacts and offer a range of solutions.

“As scientists, we had all done so much work on the land-based resources, the ecosystems, the agriculture. We were racing to figure out what climate change would do to our ice caps, our forests, our food supply. And I began to think we were missing something really important: we were missing what climate change would do to us,” Rosenzweig says. “Over 50 percent of the world’s population lives in cities. I’d lived in Manhattan almost my entire life and I began to realize that we had better find out how climate change is going to affect cities, because that’s where the people are.” And like a sailboat navigating a turn around an island, Rosenzweig’s research began to shift from studying the impact of climate change on nature to the impact of climate change on human nature.

In the year 2000, Rosenzweig was tapped to lead the Metropolitan East Coast Assessment,2 one of eighteen research projects that came to be known as the National Assessment. The goal of each regional assessment was to understand the impact of climate change on infrastructure and people. Rosenzweig, also a coordinating lead author of the IPCC Fourth Assessment Report, was able to apply that experience to the study of climate impact being done for New York. And in August 2008, much to Rosenzweig’s delight, the Metro East Coast Assessment led to the creation of the New York City Panel on Climate Change (NPCC), modeled on the IPCC. “New York City has its very own IPCC,” she explains. “There is no other city in the world that can say that.”

Cities cover less than 1 percent of the Earth’s surface, but they hold half the population and produce about 70 percent of the total greenhouse gas emissions. That’s why focusing on reducing emissions in cities is so important. Actually, despite their big collective carbon footprint, the cities’ reliance on mass transit and smaller, stacked living spaces makes them very energy-efficient. For example, the carbon footprint of the average New Yorker is less than one-third the size of the average American’s carbon footprint.3

Another compelling reason to tackle global warming in cities is that they are very vulnerable to a changing climate. And when you live in a city that is also an island, you’ve got even bigger worries. The NPCC, using data and models to project future climate change for New York City, has identified some of the most serious potential risks to New York’s infrastructure. After tallying up all the risks, the panel members hand off their assessment to the mayor and the New York City Climate Change Adaptation Task Force. It’s up to them to decide what the city should do about climate change. The task force consists of thirty-eight city, state, and federal agencies; regional public authorities; and private companies that operate, maintain, or regulate critical infrastructure. And as Rosenzweig sees it, New York City has decided to fix the climate bug now. The city has decided to see climate change as an opportunity, just like Y2K.

In February 2009, the NPCC released its latest report, Climate Risk Information. This presents a picture of what New York could look like in the future under different scenarios for greenhouse gas emissions. The conclusion is simple: the more greenhouse gases we emit globally, the more problems New York will have locally. The report shows New York as climate scientists like Rosenzweig see it. It digs, in detail, into all the gritty infrastructure issues the city is facing: everything from sewer pipes backing up to power lines sagging to airport runways flooding. As with most things in life, the details, the fine print, will get you in the end.

The report is fascinating to read if you’re an infrastructure junkie like me, and Rosenzweig admits that she has become almost obsessed. “I have been all around the world working on climate change, but it became so much more real to me when I came to grips with it here in New York,” she explains. There’s an old saying: what you work on works on you. And as far as New York is concerned, rising temperature, increased risk of flooding, and a rise in sea level are working to make it more vulnerable.

“For New York, climate change means blackouts. That’s just pure and simple,” says Steve Hammer. Hammer is the director of the Urban Energy Program at Columbia University’s Center for Energy, Marine Transportation, and Public Policy. He’s been working on a statewide project, looking at the impact of climate change on New York state’s energy supply. You can’t get around it: energy is intimately connected with temperature. And the temperature in New York is going up.

The average annual temperature in New York City from 1971 to 2000 was approximately 55°F. And if you look over the long term, you’ll see an upward trend. Since 1900, the annual average temperature in New York City has risen 2.5°F. There is plenty of natural variability in the record, but nonetheless, this long-term trend is interesting. And when you look at summer heat, it gets even more interesting. From 1971 to 2000, New York City averaged about fourteen days a year with temperatures over 90°F, and there were about two heat waves a summer. A bona fide heat wave is defined as three or more consecutive days with maximum temperatures above 90°F. A 100°F day in New York is actually a rarity: less than one day per year hits that level.

Of course, the number of extreme events in any given year varies a lot. For example, in 2002 New York City experienced temperatures of 90°F or higher on 33 days. But two years later, in 2004, there were only two days of 90°F or higher. What’s interesting is that seven of the ten years with the most days over 90°F have occurred since 1980. Climate models suggest that the frequency and duration of heat waves will continue to increase unless greenhouse gas emissions are sharply reduced. You can also use climate models to estimate how the statistics of hot days will change in the future, on the basis of different emissions scenarios. Even with the scenario involving modest greenhouse gas emissions, known as A1B (see the accompanying table), high temperatures will steadily go up, forcing people to turn up the air-conditioning. By the end of the century, 100°F days will no longer be such a rarity.4

That’s why Hammer, as someone who makes policy regarding energy, is worried about climate change.

“Energy systems are generally rated for a certain temperature and power load. If you keep running your power plant full blast for ten days during a heat wave, that’s when things begin to break down. We know AC demand is going up and we know heat extremes are going up. That’s why the city is extraordinarily vulnerable,” says Hammer.

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Number of hot days in New York over four different time periods, based on observed data and an ensemble of sixteen climate models and three emissions scenarios. These values represent the central range (67 percent) of the model output. (SOURCE: NEW YORK CITY PANEL ON CLIMATE CHANGE)

And as the number of hot days begins to increase, materials begin to break down: concrete, bridges, rail lines. More and more strain is placed on the materials that make up New York’s extensive infrastructure.

“For example, the capacity to transmit electricity over power lines drops with higher temperature due to increased resistance,” explains Hammer.

The NPCC looked at temperature projections over the coming century. The analysts used sixteen climate models and three emissions scenarios—each scenario assuming a different human reality in the future. The first emissions scenario describes a world with rapid population growth and limited sharing of technology. The second emissions scenario describes a world where the effects of economic growth are partially offset by the introduction of new technologies and decreases in global population after 2050. The third emissions scenario describes a world where global population grows to about 9 billion by 2050 but then declines to about 7 billion by the end of the century. This is also a scenario in which society places emphasis on clean, efficient technologies that reduce the growth of greenhouse gas emissions. As a result, it has the lowest greenhouse gas emissions of the three, with emissions beginning to decrease by 2040.

Keep in mind that the range of temperatures predicted for New York is mostly a reflection of these different emissions scenarios. If emissions are kept down, New York will be likely to stay along the lower end of the temperature range. But if nothing is done to reduce emissions, New York will be likely to see temperatures that are even higher. According to the NPCC, New York’s average temperature is expected to increase by about 1.5°F to 3°F by the 2020s, 3°F to 5°F by the 2050s, and 4°F to 7.5°F by the 2080s. In other words, by 2080, the overall climate of New York City will be more like that of Raleigh, North Carolina, or Norfolk, Virginia, if greenhouse gas emissions aren’t sharply reduced in the coming years.

Although this may sound good to people who love the heat, the problem is that New York’s energy infrastructure wasn’t built with Raleigh’s climate in mind.

“The energy risk becomes very apparent when you look at what percentage of the overall power load in the state is currently going toward air-conditioning,” says Hammer. “Not too long ago, that number represented approximately 2 percent of total electricity load. But the thing is, turning on the AC creates peak power demand problems. As that demand increases, you’ll need to dramatically increase the amount of total power generation capacity available around the state. You can’t expect to satisfy peak demand increases by drawing in power from other places, as demand increases will be a regional phenomenon,” says Hammer.

If they’re not made more energy efficient, cities have the potential to become trapped in a vicious circle with regard to climate. More heat extremes lead to increased energy demand, which leads to more heat extremes. That’s why fixing the climate bug is so crucial.

There are two ways to do it. One way is called mitigation: you can fix the climate bug by reducing greenhouse gas emissions. Another way is known as adaptation: you can cope with the climate problem by fixing the infrastructure. Rosenzweig and the rest of the panel on climate change are trying to show New York how to do both. “We’re trying to create this road map whereby climate information can bear on other areas of society,” Rosenzweig says. The thinking is that if people can see what New York might look like in the future, they will opt to avoid the unnecessary drama, of which rising temperature is just one example.

“I know it’s old-fashioned. But I am very much into win-win solutions. And anything we do today will help us today,” Rosenzweig adds.

That ended up being true of Y2K as well. Saffo says you can credit the millennium bug for the swift rebound of New York City’s computing systems after the attacks of 9/11. “Y2K forced Wall Street to make upgrades. Wall Street had a Y2K drill. They practiced that drill and it paid off,” Saffo says. The system redundancies developed in anticipation of Y2K allowed the city’s transportation and telecommunications sectors to provide service despite the enormous damage on 9/11. Those redundant networks and contingency plans put in place by an army of geeks led to an opportunity that may well have saved lives.

“And guess what? We are not perfectly adapted to the climate extremes of today!” says Rosenzweig. “That’s why everything we do to adapt now is going to help us right now.”

The power grid isn’t the only area that remains unsuited to the climate extremes of today. Flood protection is another glaring example that Rosenzweig cites to show how ill-suited we are for the present, let alone the future.

“The Saw Mill River Parkway”—a major traffic artery that connects New York City with the suburbs to its north—“floods now every time there’s a heavy rain,” says Rosenzweig. “So why don’t we, as a region get organized and realize, Hey, these types of events are going to happen more frequently. There is no need for everyone to pile onto the parkway and sit in these big puddles. We’re smarter than that. It could be as simple as having everyone telecommute that day.” It turns out that not all adaptations are expensive, and not all involve infrastructure. A lot of the issue is just how we choose to manage and operate the infrastructure.

Rosenzweig is really worried about flooding. “Without a doubt, New York’s biggest vulnerability is enhanced coastal flooding due to sea level rise. The sea level rise is guaranteed. It’s unidirectional. Just like the warming,” says Rosenzweig. When you live on an island, a little sea level rise goes a long way. But this isn’t a problem just for the people who live along Manhattan’s coastline. A lot of New York City’s critical infrastructure sits less than 10 feet above mean sea level; and experts like Rae Zimmerman, a member of the NPCC and a professor of planning and public administration at New York University, say that anything below 10 feet is vulnerable to flooding during major storm events.5

If you look at Zimmerman’s list of vulnerable transportation infrastructure, you’ll see dozens of well-known places, including the Canal Street Subway Station in Chinatown, which is 8.7 feet above sea level; the Christopher Street Subway Station in Greenwich Village, which is almost 15 feet below sea level; the New York entrance to the Holland Tunnel, at 9.5 feet above sea level; and LaGuardia Airport, at only 6.8 feet above sea level. (See Appendix 2 for more details.)

Until about 150 years ago, sea level had been rising along the east coast of the United States at a rate of about 0.34 to 0.43 inch per decade. It had been rising at this rate since the end of the last ice age, mostly because of regional subsidence or sinking, as the Earth’s crust still slowly readjusted to the melting of the ice sheets. But within the past 150 years, as global temperatures have increased, regional sea level has been rising more rapidly. At present, rates of rise in the sea level in New York City range between 0.86 inch and 1.5 inches per decade. The long-term average rate since 1900 is 1.2 inches per decade. In Lower Manhattan, the water at the Battery has risen more than 1 foot during the last century.

As a result, the 1-in-100-years flood, or the flood that has a 1 percent chance of occurring in any given year, will happen about every eighty years instead. The current 1-in-100-years flood can produce a sea surge of approximately 8.6 feet for much of New York City, and that surge height is shifting upward just as the chance of such a flood is shifting upward. Flood statistics in general are changing. By the end of the twenty-first century, the kind of coastal floods that at present occur about once per decade may occur every other year. According to the World Bank Climate Resilient Cities report, a 100-year flood may increase from once in eighty years, where it is today, to once in forty-three years by the 2020s and to once in nineteen years by the 2050s.

“This goes beyond the climate forecasts,” says Rosenzweig. “This is fundamentally about our values. This is about who we are as a city.” Rosenzweig has already been a host for visiting Dutch flood control experts. “We have a lot to learn from the Dutch about adaptation planning,” she says. The Netherlands has waged a long battle against the sea, and this struggle has clearly shaped Dutch values. The Dutch have lost enough battles to be very concerned about climate change.

One of the Netherlands’ biggest battles came on the evening of January 31, 1953, when a high-tide storm breached its famous dikes in more than 450 places. You could argue that this flood reshaped the political, environmental, and psychological landscape of the nation as much as it reshaped the land. More than 1,800 people died, many as they slept. More than 47,000 homes and buildings were swept away.

Twenty days after that devastating flood, the Delta Plan was launched. Dutch politicians set in motion a $3 billion, thirty-year program to end the threat from the sea once and for all. The Dutch decided that their strongest sea defenses would be designed to stand up against a storm so strong it would occur only once in 10,000 years. The river levee and dike systems were built to withstand a 1,250-year storm. The country built an elaborate network of dikes, man-made islands, and a 1.5-mile stretch of sixty-two gates to control the entry and exit of North Sea waters into and out of the low-lying southwestern provinces. The Delta Plan is one of the largest construction efforts in human history and is considered by the American Society of Civil Engineers (ASCE) as one of the seven wonders of the modern world.

New York—like the rest of the United States—doesn’t get nearly that kind of praise from the ASCE. In fact, in its 2009 Infrastructure Report Card, the ASCE gives America’s total infrastructure a D. In New York State, ASCE’s most serious concern is bridges, roads, and mass transit. The engineers found that 46 percent of New York’s major roads are in poor or mediocre condition, 42 percent of New York’s bridges are structurally deficient or functionally obsolete, and 45 percent of New York’s major urban highways are congested. In addition, there are 391 high-hazard dams in New York. A high-hazard dam is defined as one whose failure would cause loss of life and significant property damage. Forty-eight of New York’s 5,089 dams are also in need of rehabilitation to meet the state’s applicable safety standards. One explanation for all this is that by 2030, just about all of New York’s major infrastructure networks will be more than a century old.

As problematic as the dams and bridges are, they’re only part of New York City’s infrastructure problem. The city’s first subway line opened in 1904, the same year as the first New Year’s Eve bash in Times Square, and the subway signaling technology that’s still in use today was built before World War II. The energy grid was started in the 1880s, and two of the city’s water tunnels were completed before 1936. (A third is being built now and is expected to be finished in 2020.)

In short, New York is an old city facing new problems. In April 2007, the city launched a comprehensive sustainability plan: PlaNYC 2030.6 The 2007 plan now covers both mitigation and adaptation. New York is fighting its own battle with the sea—on two fronts.

In New York, the big storms come in two types: hurricanes and northeasters. Hurricanes are more likely to cause the 1-in-100-years and the 1-in-500-years floods. Northeasters, the ferocious winter storms named for the continuous, strong northeasterly winds blowing cold air down from the Arctic, are the main source of the 1-in-10-year coastal floods.

“Tell me when the next hurricane’s going to hit and I’ll tell you how soon we have a big problem in New York,” says Hammer. As with the Dutch in 1953, predicting when the next big hurricane will hit Manhattan is impossible. All you can do is build, knowing it’s going to happen again at some point.

Historically, hurricanes have hit New York (see Appendix 2) between July and October. On the basis of this short record, the National Hurricane Center estimates the return period for a category 1 hurricane in New York at about once every twenty years. A category 1 hurricane has sustained winds of between 74 and 95 miles per hour on the Saffir-Simpson hurricane wind scale. A return period of twenty years for a category 1 hurricane at a given location means that on average during the previous 100 years, a category 1 or greater hurricane has passed within 86 miles of this location about five times. The return period for a category 3 hurricane, which has sustained winds of 111 to 130 miles per hour, is roughly once in seventy years for New York. To put this period in perspective, it’s about one in ten for Miami.

According to a 1995 study by the U.S. Army Corps of Engineers, a category 3 hurricane in New York could create a surge of up to 16 feet at LaGuardia Airport, 21 feet at the Lincoln Tunnel entrance, 24 feet at the Battery Tunnel, and 25 feet at John F. Kennedy International Airport. And that’s with sea level measurements as of 1995. The impact could be even greater if the storm hit at high tide, as was the case in the Netherlands in 1953. The Army Corps of Engineers estimates that as many as 3 million people would need to be evacuated from New York City.

“The Dutch have decided a 1-in-10,000 year standard is right for them,” says Rosenzweig. “And we have to focus on doing what’s right for New York. But we need to decide now.” A category 3 hurricane is capable of producing sustained winds of more than 111 miles per hour, but the current building code requires windows to withstand only gusts of 110 miles an hour. Add to that the fact that wetlands in and around New York City, the natural sponges that help absorb some of the damage done by hurricanes, have shrunk by almost 90 percent over the past century, owing to a combination of development and storm damage. Numerous decisions need to be made. For example, some scientists have suggested that New Yorkers follow the lead of the Dutch and construct storm surge barriers. These experts have simulated storm surge to evaluate the effectiveness of barriers at several points in New York Harbor. Two historical storms were evaluated—Hurricane Floyd and the northeaster of December 1992—and in both simulations the barriers were shown to be operationally effective. But such barriers are very expensive and won’t provide protection everywhere. The decision is up to New York.

Hurricanes illustrate some of the most dramatic risks to New York’s infrastructure, but there are plenty of everyday weather events that will become increasingly problematic for the city’s support systems—most notably the guts of New York, its sewer system. New York City’s drainage and wastewater system is extensive. It consists of about 6,600 miles of sewers, 130,000 catch basins, almost 100 pumping stations, and fourteen water pollution control plants.7 The sewer system was designed to minimize standing water on roadways and streets, is mostly gravity based, and has been built over hundreds of years. The sunk-cost investment in the city’s sewer systems is enormous, and the problem is that there’s almost no flexibility to modify existing piping to install bigger pipes.

Rae Zimmerman is not only a member of NPCC but also the director of the Institute for Civil Infrastructure Systems at New York University’s Robert F. Wagner Graduate School of Public Service. “Sewage water and storm water use the same pipes. They do it for economics, but it makes them more vulnerable in the event that something happens,” she explains. In addition to the cost and disruption, the time to effect changes would be extremely long. More space would need to be found within the maze of subsurface utilities below the streets, and pumping might be needed in some instances to convey storm and wastewater flows. Despite these obstacles, some changes must be made to prevent flooding of streets and basements.

Like a lot of older cities in the country, New York City has a single, combined sewer system that handles sanitary waste as well as storm water. When it’s not raining, sewage treatment plants can handle all the sewage and clean it up. But when it rains, the vast amount of rainwater that goes into the sewers exceeds their capacity, so some of it has to be released into the rivers untreated. If rainfall becomes more intense—as observed data and climate models suggest will happen—the sewer system could be overwhelmed. That would result in more flooding of streets and basements, and more untreated waste would enter rivers.

Rising sea level will also be a factor. “New York City has regulators. So when the tides go out, the pipes—the storm sewers—are exposed and the water flows out of them and into the river. But when the tide comes in and there’s flooding, the regulators shut, or else you would have all the river water flooding New York City. Now, if there is sea level rise to the point where those regulators are always shut, there is no place for any storm water to go, and it will all spill onto the street,” Zimmerman explains.

There are some simple and cheap solutions that can help alleviate the strain. Staten Island is already preserving its natural drainage corridors, called bluebelts. These bluebelts are nothing more than streams, ponds, and other wetland areas that act to convey, store, and filter storm water, with the added benefit of providing open spaces and diverse wildlife habitats. Bluebelts have been shown to save tens of millions of dollars in infrastructure costs, compared with conventional sewers. And in Hendrix Creek, a tributary to Jamaica Bay, ribbed mussel beds have been reintroduced to test this mollusk’s ability to improve the water quality of tributaries around combined sewer overflow outfalls.

As always with climate change, there is the problem of too much water and too little water. Approximately 90 percent of the city’s water supply is from the Catskill and Delaware systems. New York City’s drinking water originates from a watershed about 2 square miles in area, situated 125 miles north of the city. It provides 1.1 billion gallons per day to 8.2 million city residents plus an additional 1 million people upstate. The system has a network of nineteen reservoirs and three controlled lakes throughout the Croton watershed east of the Hudson River and the Catskill and Delaware watersheds west of the Hudson. Some of the new problems associated with climate change could compromise the existing water supply and treatment systems.

As the temperature increases, more precipitation will fall as rain than as snow; consequently, there will be less storage and therefore reduced inflows to reservoirs during the spring season. Peak snowmelt in the Catskills is already shifting to earlier in the year. A recent study shows that during the period from 1952 to 2005 it shifted from early April to late March. In this scenario, the juggling act between floods and water supply gets harder. Lower reservoir levels can protect against a sudden flood, but low levels may reduce the statistical probability that water resources will be available to the city. A drought watch is declared when there is no better than a 50 percent probability that either the Catskill or the Delaware reservoir system will be filled by the following June 1. This definition is based on records going back to 1927—but such records are not an accurate predictor of the future.

New York uses about 1,060 million gallons of water per day (mgd). (In more familiar terms, this is 1.06 billion.) But demand can easily rise to more than 2,000 mgd (2 billion) during heat waves. For example, August 2, 2006, was the third successive day with temperatures in the 90s and humidity over 70 percent. The daily flow was 1,560 mgd (1.56 billion), but the peak flow reached 2,020 mgd (2.02 billion). During a heat wave in the city, illegal hydrant usage jumps up, just at a time when water demand is at its highest. And the ability of the existing aqueducts to refill the city’s main distribution reservoir is pushed to the limit. You can usually expect water levels to go down and water pressures throughout the entire system to become quite weak. That spells trouble for firefighters, increases the number of complaints about low water pressure on the upper floors of buildings, and increases sediment resuspension within water mains. You can almost hear the city groaning under the strain.

For all the drama it is capable of creating, climate change is ultimately about a million boring little fixes. But as Rosenzweig notes, these boring little fixes can have a profound impact. One actual example of an adaptation strategy is installing more fire hydrant locks. And in May 2008, the Climate Action and Assessment Plan published by the Department of Environmental Protection called for the installation of better hydrant-locking mechanisms.

More frequent droughts will begin to work in combination with rising sea level in ways that will affect the water supply. “All these systems are intertwined,” Rosenzweig explains. “Climate change impacts in urban areas like New York are completely integrated. That’s why our science teams have to be integrated. If they’re not, we get the wrong answer.” In New York, it is essential to take a multidisciplinary approach that involves scientists with many different backgrounds, because they can all come at the problem from a different point of view.

As Rosenzweig explains, “We meet every month with our full team of scientists. The hydrologists tend to be very confident. They often say, ‘Don’t worry, we can handle it, climate variability is our middle name.’ And so we were discussing the fact that the Palmer Drought Index, a commonly used index used to measure drought severity, shows more frequent droughts in the New York region. The hydrologists said, ‘Don’t worry, we have a pipe that goes into the Hudson River at Chelsea, which is a little town up the river, so we’re just going to supplement the supply by taking in water from the Hudson River at Chelsea.’ And a colleague from the NPCC waves her hand in the back of the room and says, ‘But we just calculated that when you include the impacts of sea level rise, the salt front in the tidal estuary would swing all the way up to Chelsea.’

“This is a classic example of why we need all these experts in the same room. Sure, we can take in additional water from the Hudson River at Chelsea. But if it’s salt water, that’s not going to help us very much.”

PlaNYC has set a goal to reduce New York City’s greenhouse gas emissions 30 percent by 2030. There are four principal strategies in the mitigation plan: avoid sprawl, generate clean power, make buildings more energy efficient, and create sustainable transportation. New York City’s population is expected to grow from 8.36 million today to about 9.1 million by 2030. Scientists agree that far deeper emissions reductions, on the order of 80 percent, will be necessary by 2050 if we are to stabilize global temperatures. In New York, the reduction plan will focus mainly on buildings, which contribute 80 percent of greenhouse gas emissions, compared with about 35 percent nationally. And 85 percent of the 950,000 buildings in New York City in 2030 already exist today. The city has promised to do a carbon inventory every year to track its progress.

Zimmerman likes to point out that New York shouldn’t focus solely on climate change. “I am a firm believer in the fact that we can be addressing national security, climate change, and sustainability simultaneously. In fact, I don’t think we should be doing any of this stuff separately,” she says. Zimmerman would like to see the city diversify and decentralize a lot of its infrastructure. “If we generated more electricity from solar and wind, we’d be reducing greenhouse gas emissions and we’d also be reducing the consequences of terrorist attacks because the production of energy would be more decentralized. The goal is to have a building-by-building supply,” she says. “I believe in decentralized infrastructure, but that doesn’t mean decentralized cities. I believe in cities!”

In keeping with this building-by-building approach, the rooftops of New York City hold a lot of hidden potential. One study cited by PlaNYC calculates that if all the rooftops in the city were covered with solar panels, they could produce nearly 18 percent of the city’s energy needs during daytime hours. In New York, roughly 40 percent of the carbon footprint comes from electricity consumed, and another 40 percent comes from the heating fuels burned directly in buildings. So making buildings more efficient is a major part of the strategy to reduce carbon emissions. It can also reduce air pollution. Nearly one-third of locally produced particulate matter in our air comes from heating fuel. Public health can improve quickly as a result of efforts that improve air quality and building efficiency.

New York may be looking to learn from others, but it’s also hoping to serve as an example of best practices. Steve Hammer also serves as an adviser to the Energy Smart Cities mayoral training program being developed by the Joint U.S.–China Cooperation on Clean Energy, a nonprofit with offices in Shanghai and Beijing. The training program is a three-year initiative that will introduce Chinese mayors to the best practices of the West, with the goal of helping cities reduce their energy intensity by 20 percent by 2010. Energy intensity, the ratio of energy use to output, is a way to measure the overall energy efficiency of an economy. Hammer brought Dr. Rit Aggarwala, the lead architect of the PlaNYC report, to China to speak at the first training session, along with a dozen other international experts.

In general, Hammer says, climate change is getting much more attention in China. “About four years ago, there was one wind turbine blade manufacturer that had set up shop in China. Today there are over seventy making blades and other turbine parts. The market is shifting very rapidly here,” says Hammer. But for all this market growth, Hammer acknowledges there is much to be done at the local level. “The mayors I’ve met generally agree they can do a better job at local sustainability matters. Many would like to take this on, but they need help in identifying strategies that are appropriate for their city. China’s central government could help prime this pump by investing in local energy planning, much like the Obama administration has started to do in the United States.”

Swift action is essential, as the rate of urban growth in China is dramatic. “The country will build 50,000 new skyscrapers in the next twenty years, and what could be more important than making them sustainable? In 1980, Shanghai had 112 buildings more than eight stories high. Now it has 13,000 of them,” says Hammer. “It’s like an almost infinite Manhattan.”

“The question I get asked the most,” Rosenzweig says, “is: am I optimistic or pessimistic about the future? I really feel climate change is the issue that is challenging human beings to become sustainable. It’s an issue that is finally big enough and destructive enough that it forces us to pay attention. And if sustainability becomes a full-fledged universal value, we’ll be OK.” Rosenzweig, even knowing everything she knows, is optimistic.

Paul Saffo is not. He says we’re still stuck in a debate between two camps over what exactly to do about climate change and sustainability. “On the one side you have the engineers and on the other side you have the Druids. I love them both,” he says. “The problem is that the engineers say let’s fix our way out of this; let’s use technology and go faster in the future. The Druids say let’s go slower. Let’s go back to a time when things were smaller and simpler. The climatologists can’t seem to decide which they are.”

But maybe that’s the point. Maybe the climatologists know we have to do both. We have to look forward and we have to look back.

In 1609, 400 years ago, the English explorer Henry Hudson sailed into New York Bay. Hudson had been hired by the Dutch East India Company to find a northeast all-water trade route to Asia. On his ship, the Half Moon, Hudson and his crew left Amsterdam and sailed along the coast of Norway until they hit ferocious weather and sea ice. Rather than return empty-handed, and disobeying orders to search only for a northeast route, Hudson made a 3,000-mile detour in search of warmer weather and the dream of finding a southwest route to Asia through North America. He never found the southwest route, but he did make another discovery, the island of Manhattan. The Dutch colonial settlement and fur trading outpost of New Amsterdam served as the capital of New Netherland until it later fell under British rule and was renamed New York. New York wasn’t the dream Hudson had been chasing, but it has come to represent the hopes and dreams of millions.

“I guess,” says Rosenzweig, “everyone has the New York of their dreams. For me, it’s a climate-resilient city.” The year 2009 marked the second anniversary of PlaNYC.8 On Earth Day, April 22, Mayor Bloomberg announced that eighty-five of the plan’s 127 initiatives were on time or ahead of schedule. As part of PlaNYC, the city had converted 15 percent of the yellow taxi fleet to hybrid vehicles; planted 174,189 trees across the five boroughs; acquired 13,500 acres of land to protect the upstate water supply; saved 327 tons of nitrogen oxide (NOx) per year by means of retrofits to the Staten Island ferry fleet; and started twenty storm water retention pilot projects. Maybe Rosenzweig is right to be optimistic.

New York, New York: The Forty-Year Forecast—Hurricanes, Infrastructure, and Sea-Level Rise

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Forecast September 2013

You could say New York deserved a lucky break. It had already been slapped around enough by tropical storms. Back in September 2004, the remnants of Hurricane Frances had flooded its subways and stranded passengers. And in September 1999, Hurricane Floyd, by then weakened to a tropical storm, had dumped more than 10 inches of rain on the city, causing mudslides on the bluffs overlooking the Hudson River near the Tappan Zee Bridge. There were still plenty of people who remembered Hurricane Donna, the category 3 storm that pounded New York City on September 12, 1960, with sustained winds of more than 90 miles per hour. Donna had flooded lower Manhattan almost to waist level on West and Cortlandt Streets—the southwest corner of what later became the site of the World Trade Center. The last thing New York needed was another hurricane.

An average hurricane season has eleven named storms and six hurricanes, including two major hurricanes. The United States Landfalling Hurricane Probability Project put the risk that New York would be hit by a major hurricane (category 3 or more) by 2050 at 90 percent.9 We all knew that eventually, with or without global warming, a major hurricane was going to hit New York. The question was simply when the Atlantic Ocean would start to play hardball again.

The period from 2009 to 2012 was a stretch with the fewest named storms and hurricanes since 1997—thanks, in part, to an El Niño in 2009–2010. El Niño produced strong wind shear across the tropical Atlantic, which meant fewer and shorter-lived storms. It almost seemed as though, after producing Katrina in 2005, the Atlantic Ocean had gone into semiretirement. If hurricane seasons were anything like baseball, then the Atlantic seemed to be in a very welcome slump. For four years in a row, no major hurricanes had hit the United States. And as for baseball: the Yankees, in their new stadium, went on a winning spree of four World Series in a row.

But all good things must come to an end. And in September 2013, with the Yankees not even looking to play in the postseason, the Atlantic Ocean reawakened and one specific hurricane seemed to be in a New York state of mind. After beginning as a garden-variety low-pressure system moving off the coast of west Africa, the storm that eventually came to be known as Hurricane Homer gathered strength as it crossed over unusually warm tropical Atlantic waters. The warm ocean water acted like a heat pump, fueling the hurricane and causing it to increase in intensity. Many models still struggled to predict exactly how climate change would affect hurricanes, but there was general agreement that warmer water meant more intense storms.

The NOAA GOES-12 satellite recorded the storm’s every move, and initially the National Hurricane Center issued a watch for Miami, expecting the storm to hit there. Miami’s residents stockpiled supplies, boarded windows, and secured boats—as usual. But then Homer took a turn north and surprised everyone when it started speeding up. The Bermuda High, a large area of high pressure in the Atlantic, pushed the storm up the coast as warm water provided fuel to the system. In time, the hurricane would achieve a record-breaking forward speed of 75 miles per hour. As the system raced up the coastline of the Carolinas, the revised track forecast issued by the National Hurricane Center warned of a category 3 storm making its way directly toward New York City. Here was a system that bore a striking resemblance to an event that had almost happened back in 1938, when the Long Island Express, which ultimately missed New York City by just 75 miles, did tremendous damage up and down the northeast coast. The only difference was that this one didn’t look as though it was going to miss.

The models suggested that New York was about to get swallowed by storm surge. Surge levels for Hurricane Homer had been calculated by the U.S. Army Corps of Engineers using NOAA’s SLOSH model, and in a worst-case scenario Homer was likely to create a surge of up to 25 feet at John F. Kennedy Airport, 21 feet at the Lincoln Tunnel entrance, 24 feet at the Battery, and 16 feet at LaGuardia Airport. The U.S. Army Corps of Engineers estimated that nearly 30 percent of the south side of Manhattan would be flooded. The storm surge flooding would threaten billions of dollars of property. Rising sea level was already a factor, as each seemingly small increase in sea level gave the hurricane a longer, more destructive reach into the city. Since 1900, sea level in New York City had been rising at rate of about 1.2 inches per decade. Hurricane Homer plus this rise meant more storm-related coastal flooding, more inundation of wetlands, more structural damage, and more money lost.

Because of the projected track and the fact that the highest, most destructive winds lay to the right of the storm’s eye, it was anticipated that Homer could pass directly over New York with gusts over 150 miles per hour—shattering the glass in skyscrapers and sending razor-sharp shards raining to the ground. In addition, the counterclockwise, westerly flowing wind would funnel the surge waters into New York City harbor.

As the storm swept up the coast, we all became experts on the history of hurricanes in New York. We knew that there had been only two honest-to-goodness direct hits in New York City in recent history—the Great September Gale of 1815, and a storm that came on September 3, 1821, and made landfall at Jamaica Bay. Both were category 3 storms and both did extensive damage. With widespread flooding in lower Manhattan as far north as Canal Street, the 1821 hurricane set the record for the highest storm surge in Manhattan—nearly 13 feet. One question was whether Hurricane Homer would go down in the history books as the third direct hit. Another question was what, if anything, could New Yorkers do to prepare themselves.

For the most part, people simply jumped ship and left the city. It ended up as the largest peacetime evacuation since Hurricane Floyd. As New Yorkers headed through bridges and tunnels, transit workers stayed behind, trying to ready pumps and prep storms drains. It felt rather like rearranging deck chairs on the Titanic, but there was little else to do. There was simply no infrastructure to deal with a storm of this magnitude. People did what they could and then simply sat back, prayed, and vowed that they wouldn’t allow the city to be this vulnerable again.

Fortunately, the Bermuda High shifted, and the hurricane began to shift course: the center of the storm headed out to the open sea. And New York, which could have been swallowed up whole and spat out by this storm, got off relatively easy.

That said, there was still significant damage to sift through. There was severe coastal erosion and heavy street flooding. The Rockaway beaches nearly vanished, owing to the high winds and storm surge. The sewer system was completely unprepared for the volume of rain that fell in such a short time. The water began pooling at the street corners, and then gradually rose to inflict damage on parked cars and storefronts. Many owners of the city’s famous facades had boarded up their windows to protect the glass from the wind, but the water was one thing that no one could have prepared for.

Though no buildings were submerged, and even though the storm was a near miss, the water inflicted excessive damage across the southern third of the island. Many people who lived in basement apartments returned to the city to find their possessions soaking wet and now had to contend with an unfortunate and unhealthy problem: mold.

On top of all this, September set a new record in New York for warmth. In general, temperatures usually associated with August were now stretching deeper and deeper into September; and now New York was in the grip of a late summer heat wave. With electricity out in many parts of the city and nighttime lows still in the 80s, people felt overwhelmed by weather.

Trees were yet another casualty. Tree-lined blocks from the Upper West Side to Park Slope, Brooklyn, were stripped of their greenery. Picturesque streets suddenly looked as if they had encountered a wood chipper, with the pavement and cars covered in brown and green shrapnel. Trees were down all over Central Park; the cleanup and replanting would eventually cost several million dollars. The parts of the park that were hit hardest were closed to the public for several months, making for an unusually quiet Central Park in the fall.

And then there was the subway system. Storm tides overtopped some of the region’s seawalls for only a few hours, but they still managed to flood the subway as well as the PATH train systems at the station in Hoboken, New Jersey, shutting down these transportation systems for almost a week. This shutdown made it very difficult for those who had left the city to get back home and start the cleanup. The stations that everyone knew were vulnerable to flooding in an extreme weather event proved to be just that. Because of its proximity to the Hudson River and its depth below sea level, the Christopher Street subway station was shut down longest, with water covering the tracks for several weeks after the hurricane.

Despite the tens of millions of dollars in damage, New Yorkers realized how lucky they were. But when they slowly began to file back into the city, their questions followed them home. How could a major metropolitan area like New York be so vulnerable? Why wasn’t more being done to replace century-old infrastructure? If the Yankees could build a new stadium for $1.3 billion, why couldn’t the mayor and the Metropolitan Transit Authority make basic improvements to the subway? After all, the Dutch and the British had already spent billions fortifying their cities against the growing threat of storms and rising sea level.

January 2014

The high-resolution model projections of what could have happened to New York got under everyone’s skin. Deep down, we all knew it was only a matter of time before something really happened. The city, with its elderly infrastructure and vulnerable coast, needed help. Other cities were already adapting to climate change. Boston had elevated a sewage treatment plant to keep it from being flooded; this project was based on projections from scientists at Harvard regarding the rise in sea level. And Chicago, through its Green Roof and Cool Grants Program, encouraged rooftop gardens and reflective roofs to help keep the temperature down and ease heat waves. New York, of course, had its own plans in place, and now the hurricane that almost was had given everyone a new sense of what would eventually come to be.

Organizations and volunteers across the city began to implement strategies that had been laid out by the New York City Climate Change Adaptation Task Force. Given the climate change projections performed by Columbia University’s Center for Climate Systems Research and NASA’s Goddard Institute for Space Studies, we understood that the city was probably headed for a 3°F to 5°F increase in temperature, a 2.5 to 7.5 percent increase in precipitation, and a 6- to 12-inch rise in sea level by 2050. We worked to rebuild the city with that climate in mind.

And so began a coordinated plan to adapt the city’s roads, bridges, and tunnels; its mass-transit network; its water and sewer systems; its gas and steam production and distribution systems; its telecommunication networks; and other critical infrastructure to be able to deal with the likelihood of more extreme weather. There were plans to modify dam infrastructure and allow for water releases in anticipation of a storm, and to inventory existing tide gates and identify priority locations most vulnerable to a rise in sea level and to storm surges. There were programs that focused on the long-term viability of New York’s water and sewer systems. There were land acquisition programs aimed at protecting the watershed, as well as a plan for new water quality infrastructure. A complete face-lift for the city would cost an unthinkable sum. So the work was done piecemeal and at the local level by concerned groups of public and private organizations. I’m not really sure how long a New York minute is, but we were now thinking about a New York century. It was as if the entire city had become obsessed with adapting to climate change. Go figure.

April 2017

It was a good thing that we did begin to chip away at the city’s infrastructure shortcomings. In April 2017, four freak storms each dumped more than 7.5 inches of rain in upper Manhattan in one day, setting new records for daily accumulation. Another three days saw between 4 inches and 6 inches of rain at locations across the city within a four-hour period. In some areas, 4 inches of rain fell in one hour alone. The city’s existing storm water conveyance system had been designed for only 1.75 inches of rainfall per hour. We added “new storm drains” to the city’s wish list. Needless to say, the April storms flooded the subway, too. It was obvious that we also needed to focus our attention underground.

There were at least three situations that could take out the subways: (1) flooding of the tracks over the third rail; (2) water pouring through street-level vents, leading to a smoke condition; and (3) flood impacts on the signaling system. As rainwater seeped through tunnel walls and headed down subway grates and stairwells, sump pumps in 280 pump rooms next to the subway tracks would pull the water back up to street level.10 That water then naturally flowed toward the storm drains. But more often than not, the storm drains were unable to handle the flow of water. They were designed to take away only so much water. Eventually, the water would make its way onto the subway tracks, hitting the all-important third rail. The 600 volts of electricity running through the third rail would cause the water to boil and set all the floating debris on fire. In addition, the water would short-circuit the electrical signals and switches, making it impossible for train operators to know when it was safe to stop or go. The subway system had two critical sources of power: the direct current propelling the trains, and the alternating current powering the signals. Even if the direct current was spared, the trains couldn’t run without signals.

It took time, but the New York City Transit Authority installed additional pumps and built new storage tanks for processing rainwater runoff. It also developed a computer system to better monitor storage during times of overflow. Also, the Department of Environmental Protection moved electrical equipment, such as pump motors and circuit breakers at the Rockaway Wastewater Treatment Plant in Queens, from 25 feet below sea level to 14 feet above sea level. The beach nourishment projects that had been going on since 1924 to prevent coastal erosion were also stepped up in the Rockaways as a way of dealing with the effects of a rising sea level. Depositing more sand on the beach strengthened the defense that the beach provided during coastal flooding.

But in the long term, it became increasingly clear that a new network of storm surge barriers would need to be constructed in order to protect the city. As the sea level rose, New York became even more vulnerable to storm surge flooding. It would take high-water levels of only 4.9 to 5.7 feet above mean sea level to cause flooding over some of the southern Manhattan seawalls. Global warming was expected to increase the rate at which sea level rose: from about 1 foot per century to between 1.6 and 2.5 feet per century.

It was suggested that four barriers 30 feet high and able to withstand a 1,000-year flood event should be constructed: two off the coast of Staten Island, one to the northeast and one to the southwest; one off the coast of the Bronx, protecting LaGuardia Airport; and one off Breezy Point in the Far Rockaways to help protect John F. Kennedy Airport. The barriers would need to operate with as little as one hour’s warning, closing each gate in fifteen minutes and the complete barrier in thirty minutes. The construction time was estimated to be eight years.

July 2027

As the models projected, temperatures across the city had been steadily creeping up. The daily highs were getting higher, and so were the nightly lows. By the 2020s everyone realized that summers were longer and hotter than ever before. That’s why it came as no big surprise when New York broke the record for the longest stretch of 90-degree days ever recorded. For twenty-one days straight, New York’s aging power grid was brought to its knees. The increase in peak electricity load when people cranked up their air conditioners resulted in routine brownouts as well as an increase in costs associated with cooling water for power plant operations. Even with the broad mandate for infrastructural repair that had been handed down after Hurricane Homer, the grid proved too complex to overhaul. Unfortunately, this delay had deadly consequences, which began with a lightning strike.

The lightning strike that set off the New York blackout of 2027 caused the loss of two transmission lines and a subsequent loss of power from the nuclear plant at Indian Point. New York Power Pool Operators called for Con Edison operators to “shed load.”

Because of the power failure, LaGuardia and Kennedy airports were closed for about eight hours, automobile tunnels were closed owing to lack of ventilation, and 10,000 people had to be evacuated from the subway. Con Ed called the shutdown an “act of God,” enraging the politicians in City Hall, most of whom said that the utility was guilty of gross negligence for not working to better prepare the power grid for a heat wave that had been years in the making. In many neighborhoods, veterans of the Northeast blackout of 2003 headed to the streets at the first sign of darkness. But many of them did not find the same spirit. In poor neighborhoods across the city, looting and arson erupted.

January 2039

The storm surge barriers were over budget and not even close to being on schedule, but they were finally done. This was the eight-year project that took twenty-two years to complete. Regardless of the complaints and infighting, we were all just glad to see the job finally done. And there was more good news. The runways at Kennedy, LaGuardia, and Newark airports were raised in anticipation of higher flood levels. There was also a plan in place to move the West Side Highway inland. Coastal areas were rezoned for parks and recreational uses, not high-density residential development.

None of it was cheap, and plenty of people began to worry that it was overkill. Elevating single-family homes in Long Island by 2 feet could cost anywhere from $22 to $62 per square foot. Additional seawalls cost about $5 million per mile.11 For the country as a whole, it was estimated that building seawalls to protect the United States from coastal flooding would cost from $46 billion to $146 billion.12 Scientists had also come up with ways to incorporate mangroves and sea grasses into the design of seawalls to improve their environmental impact and make them look better, too.

It was strange to see the climate projections playing out before our eyes. What used to be the 1-in-10-years coastal flood, fifty years ago, now came every other year. And the 1-in-100-years coastal flood happened four times more often. It was a good thing we had raised those wastewater treatment plants.

Over the years, new research had begun to suggest that the rise in sea level along New York’s coast would be much higher than we had originally projected. The extra bump in sea level came because the Gulf Stream had thermally expanded and was slowing down as a result of warmer ocean surface temperatures.13 The new estimates for 2050, once you included all the sources of the rise in sea level—from Greenland, from Antarctica, from glaciers and ice caps, and from thermal expansion—as well as the dynamic effects, could be as high as 3 feet.14 And adding as little as 1.5 feet of sea level rise to the storm surge of a category 3 hurricane on a worst-case storm track would devastate many parts of the city—the Rockaways, Coney Island, much of southern Brooklyn and Queens, portions of Long Island City, Astoria, Flushing Meadows–Corona Park, Queens, Lower Manhattan, and eastern Staten Island from Great Kills Harbor north to the Verrazano Bridge would be underwater. Thank God we had built those storm surge barriers and seawalls.

August 2050

Not everyone loves New York. But those who do love it love it intensely. And through some combination of luck and high-tech ingenuity, those who loved the city ultimately saved it. In 2050, when Hurricane Xavier—a category 4 monster, which sprang up from the bathtub that the Atlantic had become finally arrived—people sat back and watched it like the World Series. We knew we had a home team advantage, just like the Yankees.