People standing in front of destroyed houses on the beach at the Rockaways New York after Hurricane Sandy
The Rockaways, New York, after Hurricane Sandy. The city is beginning to plan for a future of extreme weather.Photograph by Adrian Fussell / Reportage by Getty Images

In July, 1995, a scorching heat wave hit Chicago, killing seven hundred and thirty-nine people, roughly seven times as many as died in Superstorm Sandy. Soon after the heat abated, social scientists began to look for patterns behind the deaths. Some of the results were unsurprising: having a working air-conditioner reduced the risk of death by eighty per cent. But fascinating patterns did emerge. For the most part, the geography of heat-wave mortality was consistent with the city’s geography of segregation and inequality: eight of the ten community areas with the highest death rates were virtually all African-American, with pockets of concentrated poverty and violent crime, places where old people were at risk of hunkering down at home and dying alone during the heat wave. At the same time, three of the ten neighborhoods with the lowest heat-wave death rates were also poor, violent, and predominantly African-American.

Englewood and Auburn Gresham, two adjacent neighborhoods on the hyper-segregated South Side of Chicago, were both ninety-nine per cent African-American, with similar proportions of elderly residents. Both had high rates of poverty, unemployment, and violent crime. Englewood proved to be one of the most perilous places during the disaster, with thirty-three deaths per hundred thousand residents. But Auburn Gresham’s death rate was only three per hundred thousand, making it far safer than many of the most affluent neighborhoods on the North Side. Identifying the sources of such resilience is important, and not for merely academic reasons. The changing climate is likely to deliver more severe weather more often, and understanding why some neighborhoods fare better in a crisis than others that resemble them can help us prepare for the next disaster.

For the past decade and a half, governments around the world have been investing in elaborate plans to “climate-proof” their cities—protecting people, businesses, and critical infrastructure against weather-related calamities. Much of this work involves upgrading what engineers call “lifeline systems”: the network infrastructure for power, transit, and communications, which is crucial in the immediate aftermath of a disaster. Some of the solutions are capital-intensive and high-tech; some are low- or no-tech approaches, such as organizing communities so that residents know which of their neighbors are vulnerable and how to assist them. The fundamental threat to the human species is, of course, our collective inability to reduce our carbon emissions and slow the pace of climate change. Yet, even if we managed to stop increasing global carbon emissions tomorrow, we would probably experience several centuries of additional warming, rising sea levels, and more frequent dangerous weather events. If our cities are to survive, we have no choice but to adapt.

Klaus Jacob is a geophysicist at Columbia University whose 2009 report on climate risks to New York City contains eerily accurate predictions about what would happen to the city’s infrastructure during a major storm surge. He works at the university’s Lamont-Doherty Earth Observatory, a sprawling research campus for earth sciences perched above the Hudson River, on the Palisades. Its drab, boxy buildings make it look more like a military base than like a collegiate Arcadia. Jacob’s office has the familiar academic freight of books, journals, and papers, but there’s also a Day-Glo hard hat that has had some use over the years. When I asked him how he got interested in urban security, he told me about his childhood. “I was born in Stuttgart in 1936, and when the war started my parents moved us to a small village in Bavaria, because they knew we would be safer there,” he said. “The family that moved into our home was killed two years later. The building was bombed.” Jacob has a thick silver beard and pale-blue eyes, although his foreboding manner makes the effect less Kris Kringle than Old Testament prophet. He gave me an intent look. “I grew up in a war environment. And what I learned is that you can plan your fate, at least to some degree, if you assess your risks and do something about it.”

Jacob’s early research, which was funded by the United States Air Force, focussed on underground nuclear explosions, and he later studied how structures such as bridges and high-rise buildings could survive seismic shocks. In the nineteen-nineties, Jacob was asked to help New York City evaluate its capacity to withstand storms, and since then he has conducted similar studies for New York State and the M.T.A. His findings were sobering. “Much of the subway system is below sea level already,” Jacob explained. During Sandy, several stations and lines filled up like bathtubs. Elevating and redesigning access points and the ventilation system would be an immense undertaking. “It will probably cost billions, maybe tens of billions, to protect it.”

Jacob’s computer screen displayed two maps of New York City neighborhoods, one color-coded by elevation and the other by population growth since 2000. “Look at the blue zones, which show where we’ve been developing real estate, and the pink ones, which show where the population is dropping,” Jacob said. Downtown neighborhoods on the Hudson—Battery Park, Tribeca, the West Village, West Chelsea, and Hell’s Kitchen—were solidly blue; neighborhoods uptown, on higher ground, were pink. “Think about all the projects we conceived more than a decade ago, before we knew about rising sea levels, in the name of waterfront revitalization,” he went on. “They’ve been quite successful, but they’ve also placed a lot of people at risk.”

Genuine adaptation, Jacob believes, means preparing for the inevitable deluge. “The ocean is going to reclaim what we took from it,” he said. He thinks that New York can learn from Rotterdam, which has a long history of flooding. After enduring a devastating storm surge in 1953, Rotterdam began building a series of dams, barriers, and seawalls as part of a national project called Delta Works, and five years ago the Dutch government provided funds for an upgrade, the Rotterdam Climate Proof Program. Arnoud Molenaar, who manages it, says his team realized that they could convert the water that comes into the city from the skies and the sea into “blue gold.” “Before, we saw the water as a problem,” Molenaar told me. “In the Netherlands, we focussed on how to prevent it from coming in. New York City focussed on evacuation, how to get people out of the way. The most interesting thing is figuring out what’s between these approaches: what to do with the water once it’s there.”

In 2005, Rotterdam hosted the Second International Architecture Biennale. The theme was “The Flood.” Designers from around the world presented plans for how cities could cope with water in the future, and when the exhibition ended Molenaar’s team set out to implement those that would have immediate practical value. Rotterdam is now experimenting with an architecture of accommodation: it has a floating pavilion in the city center, made of three silver half spheres with an exhibition space that’s equivalent to four tennis courts; a water plaza that serves as a playground most of the year but is converted into a water-storage facility on days of heavy rainfall; a floodable terrace and sculpture garden along the city’s canal; and buildings whose façades, garages, and ground-level spaces have been engineered to be waterproof.

Smart designs have improved other parts of the Netherlands’ critical infrastructure. Its communications network features the fastest Internet speed in Europe, and, with I.B.M., it has built a system for water and energy management. It also has a resilient power grid, designed to withstand strong winds and heavy rain. In the United States, most distribution lines are elevated on wooden poles and exposed to falling tree branches; in the Netherlands, the lines are primarily underground and encased in water-resistant pipes. The Dutch grid is circular, rather than being a system of hub and spokes, so that, if a line goes out in one direction, operators can restore power by bringing it in from another source. And it’s interconnected to the grids in neighboring countries, which gives the system additional capacity when there are local problems. This network architecture is more resilient in ordinary times, too. In Holland, the average duration of total annual power outages is twenty-three minutes, compared with two hundred and fourteen minutes in New Jersey, Pennsylvania, and New York—not including outages from disasters.

After Sandy, there was a five-day blackout in lower Manhattan, because the walls protecting Con Ed’s substation along the East River, at twelve and a half feet above the ground, were eighteen inches too low to stop the storm surge and prevent the consequent equipment explosions. When I asked Jacob about this, he threw up his hands in exasperation. “Just put it on a high platform and use more underwater cable,” he said. “We’ve had it available for a long time now. These are just moderate investments, in the millions of dollars. It’s a small price to pay for more resilience.”

The island nation of Singapore—where 5.2 million people are packed into seven hundred and ten square kilometres of land, much of which is perilously close to sea level—offers other lessons. Singapore began adapting to dangerous weather thirty years ago, after a series of heavy rains during monsoon seasons caused repeated flooding in the low-lying city center. The country has always had a difficult relationship with water. Its geography makes it vulnerable to heavy seasonal rains and frequent flooding but there is never a sufficient supply of usable water, and in recent years Singapore’s dependency on Malaysian water sources has led to political conflicts. Climate change, with its rising sea levels and increase in heavy rains, threatens the city-state’s stability. But Singapore’s government also sees this as an opportunity.

The Marina Barrage and Reservoir, which opened in 2008, is at the heart of Singapore’s two-billion-dollar campaign to improve drainage infrastructure, reduce the size of flood-prone areas, and enhance the quality of city life. It has nine operable crest gates, a series of enormous pumps, and a ten-thousand-hectare catchment area that is roughly one-seventh the size of the country. The system not only protects low-lying urban neighborhoods from flooding during heavy rains; it also eliminates the tidal influence of the surrounding seawater, creating a rain-fed supply of freshwater that currently meets ten per cent of Singapore’s demand. Moreover, by stabilizing water levels in the Marina basin the barriers have produced better conditions for water sports. The Marina’s public areas, which include a sculpture garden, a water-play space, a green roof with dramatic skyline vistas, and the Sustainable Singapore Gallery, bolster the city’s tourist economy as well.

The Marina is just one of Singapore’s adaptation projects. The Mass Rapid Transit system has elevated the access points for the underground rail system to at least a metre above the highest recorded flood levels. To minimize damage, the Public Utility Board has improved its drainage systems. In the nineteen-seventies, thirty-two hundred hectares of land were flood-prone; today, only forty-nine hectares are. Singapore is further reducing its dependence on imported water by building new facilities for desalinating seawater, and developing technology for using reclaimed and treated wastewater in industrial settings. To reduce its energy consumption, the Building and Construction Authority requires that all new structures be insulated with materials designed to retain cool temperatures. Today, Singapore is better prepared not only for extreme weather but also for meeting future demands for power and water as its population grows.

Jacob doesn’t think Rotterdam’s or Singapore’s arrangements can simply be replicated elsewhere, but he’s impressed by their ambition and foresight. After Sandy, New York paid the price for its lack of preparation. In recent decades, American utility companies have spent relatively little on research and development. One industry report estimates that, in 2009, research-and-development investments made by all U.S. electrical-power utilities amounted to at most $700 million, compared with $6.3 billion by I.B.M. and $9.1 billion by Pfizer. In 2009, however, the Department of Energy issued $3.4 billion in stimulus grants to a hundred smart-grid projects across the United States, including many in areas that are prone to heat waves and hurricanes. The previous year, Hurricane Ike had knocked out power to two million customers in Houston, and full restoration took nearly a month. When the city received $200 million in federal funds to install smart-grid technology, it quickly put crews to work. Nearly all Houston households have been upgraded to the new network, one that should be more reliable when the next storm arrives.

Smart grids are in the early stages, but already they have several advantages over the old power systems. Digital meters, which are installed in households and at key transmission points, automatically generate real-time information about both consumers and suppliers, allowing utility providers to detect failures immediately, and sometimes also to identify the cause. This means that, after an outage, operators don’t need to wait for calls from angry customers or field reports from crews. Moreover, smart grids are flexible, capable of being fed by disparate sources of energy, including systems powered by the sun and the wind. When the energy industry develops better technologies for storing power from these renewable resources, the new networks should be capable of integrating them.

Reëngineered grids will ultimately offer other benefits. “The situational awareness of the system might allow operators to reconfigure the system, either before or after the event, to maintain service,” Leonardo Dueñas-Osorio, an engineering professor at Rice University who is developing resilience metrics for critical infrastructure systems, told me. “As a hurricane approaches, operators could ‘island’ areas that look like they will get the most damage. This breaks the system into small clusters and prevents cascading failures. It gives the operators more control, more capacity to keep the power going or get it back.” Smart meters also enable consumers to go online anytime to learn when and how they use energy and how much they’re spending. Already there’s evidence that customers with this information are adjusting their behavior accordingly: easing off on air-conditioning, drying their clothes at night. Creating a smarter, more resilient grid for New York will be expensive, but not as expensive as a future filled with recurring outages during ordinary times and long-lasting failures when the weather turns menacing.

The communications system, too, is vulnerable to weather extremes; America’s mobile-phone networks have always been less reliable than those in Europe, and regularly fail in catastrophes. During Sandy, emergency workers in New York and New Jersey were unable to communicate with colleagues who came from other states, because there’s no nationwide network for first responders, and those from outside the region depended on cellular networks that were down. “Good public policies could potentially make these new networks much more resilient,” Harold Feld, the senior vice-president of the digital-rights advocacy group Public Knowledge, says. The networks he envisages are flexible and have redundancies: “They can back each other up.” Smart phones give the networks additional capacities for emergency communications, such as reverse-911 messaging that can be sent from government agencies to all customers in Zip Codes where dangerous weather is approaching, with geographically specific instructions on whether to evacuate or how to stay safe.

Unfortunately, the cellular industry has resisted efforts to regulate it, as the old telephone network is regulated, and there are no federal laws establishing minimum requirements for backup power during emergencies, no standards for how and when providers will share networks or drop roaming charges to give more people access to information, and no rules for reporting what caused extended outages. “We have a public interest in building robust networks,” Feld says. “And by now it’s clear that we’re not going to get them by letting industry regulate itself.”

“We’re a pack, not a cult.”

New York City will inevitably explore ways to reduce flooding. There are relatively inexpensive measures, such as restoring wetlands and planting oyster beds, and then there are more ambitious, capital-intensive approaches: engineers at the Dutch firm Arcadis have designed a $6.5-billion barrier that would go just north of the Verrazano-Narrows Bridge. Others have proposed a five-mile gate that would stretch from Sandy Hook, New Jersey, to Rockaway, New York. Malcolm Bowman, who runs the Storm Surge Research Group at SUNY Stony Brook, is among the leading advocates for such a barrier. “We can’t just sit around waiting for the next catastrophe,” he argues. “The time is now, and it’s really just a matter of political will.”

But there are debates about the long-term efficacy of these barriers. “Barriers are at best an intermediate solution,” Jacob told me in his office. “They will require at least twenty years to build, because we’d need environmental-impact reports, and buy-in from the federal government, the state governments of New York, New Jersey, and Connecticut, and probably also about three hundred municipalities. If all that happens, we’d get protection for perhaps a few decades. Walls will keep out storm surges, but not the rising ocean, and they could cause a sense of false security that prevents us from finding real solutions.”

Jacob’s office lacks the high-powered computing equipment that one finds in the labs where engineers are designing sophisticated models for sea barriers. “I’m a conceptual thinker,” Jacob told me. “I do the modelling in my head. And if we spend all our resources on expensive safety systems that are not sustainable we’re not going to solve the problem. Sometimes engineers don’t see things holistically. Earth science helps us see the bigger picture.” Eventually, Jacob believes, the city will need to make a “managed retreat” to higher ground. “We have a lot of high areas that we’re not using, or that we’ve used for cemeteries, in Queens. I think we need to switch the living and dead, and I think the dead would understand.”

He turned again to his monitor. “Look at the map,” he said, tracing the coastline in Brooklyn, Queens, and Staten Island, then running his fingers along the Hudson and the East River. “This is where the rising water will hit.”

Still, a strategy of resilience will involve more than changes to our physical infrastructure. Increasingly, governments and disaster planners are recognizing the importance of social infrastructure: the people, places, and institutions that foster cohesion and support. “There’s a lot of social-science research showing how much better people do in disasters, how much longer they live, when they have good social networks and connections,” says Nicole Lurie, a former professor of health policy at RAND’s graduate school and at the University of Minnesota, who has been President Obama’s assistant secretary for preparedness and response since 2009. “And we’ve had a pretty big evolution in our thinking, so promoting community resilience is now front and center in our approach.”

The Chicago heat wave proved to be a case study in this respect. Researchers who sifted through the data (I was among them) noticed that women fared far better than men, because they have stronger ties to friends and family and are less prone to isolation. Latinos, who had high levels of poverty, had an easier time than other ethnic groups in Chicago, simply because in Chicago they tend to live in crowded apartments and densely packed neighborhoods, places where dying alone is nearly impossible.

The key difference between neighborhoods like Auburn Gresham and others that are demographically similar turned out to be the sidewalks, stores, restaurants, and community organizations that bring people into contact with friends and neighbors. The people of Englewood were vulnerable not just because they were black and poor but also because their community had been abandoned. Between 1960 and 1990, Englewood lost fifty per cent of its residents and most of its commercial outlets, as well as its social cohesion. “We used to be much closer, more tight-knit,” says Hal Baskin, who has lived in Englewood for fifty-two years and currently leads a campaign against neighborhood violence. “Now we don’t know who lives across the street or around the corner. And old folks are apprehensive about leaving their homes.” Auburn Gresham, by contrast, experienced no population loss during that period. In 1995, residents walked to diners and grocery stores. They knew their neighbors. They participated in block clubs and church groups. “During the heat wave, we were doing wellness checks, asking neighbors to knock on each other’s doors,” Betty Swanson, who has lived in Auburn Gresham for nearly fifty years, says. “The presidents of our block clubs usually know who’s alone, who’s aging, who’s sick. It’s what we always do when it’s very hot or very cold here.”

Robert J. Sampson, a sociologist at Harvard University, has been measuring the strength of social ties, mutual assistance, and nonprofit organizations in Chicago communities for nearly two decades. He has found that the benefits of living in a neighborhood with a robust social infrastructure are significant during ordinary times as well as during disasters. In 1990, life expectancy in Auburn Gresham was five years higher than it was in Englewood. And, during the severe heat waves that are likely to hit Chicago and other cities in the near future, living in a neighborhood like Auburn Gresham is the rough equivalent of having a working air-conditioner in each room.

Since 1995, officials in Chicago have begun to take these factors into account. During times of intense heat, the city has urged the local media to advise neighbors, friends, and family to check in on one another. City agencies have maintained a database that lists the names, addresses, and phone numbers of old, chronically ill, and otherwise vulnerable people, and city workers call or visit to make sure they’re safe. Churches and civic organizations have encouraged neighbors to look out for one another, as have family and friends. In Englewood, meanwhile, residents and community organizations have invented their own version of the Rotterdam strategy, turning their main problem, abandonment, into an advantage. Their goal is to transform Englewood into a hub of urban farming, with gardens that create stronger community ties as well as fresh produce and shade.

Englewood, as it happens, is just a few miles from the neighborhoods where Barack Obama worked as a community organizer during the late nineteen-eighties, learning first hand why social ties matter. Obama must have been thinking of places like Englewood when, as a U.S. senator in 2005, he connected the effects of Hurricane Katrina to the slow-motion disaster that New Orleans’s vulnerable neighborhoods endured every day. “I hope we realize that the people of New Orleans weren’t just abandoned during the hurricane,” he said. “They were abandoned long ago.” Katrina, Obama continued, should “awaken us to the great divide that continues to fester in our midst” and inspire us to “prevent such a failure from ever occurring again.”

Obama was one of many members of Congress who believed that Katrina exposed the shortcomings of a national-security strategy that marginalized non-terrorist threats. The following year, Congress passed the Post-Katrina Emergency Management Reform Act, which expanded FEMA’s authority, and the Pandemic and All Hazards Preparedness Act, which authorized new programs to improve public-health responses, ranging from risk communications to targeted support for vulnerable populations. During his first term, President Obama introduced a new National Health Security Strategy that emphasized preparedness and resilience, calling for the participation of the “whole community”—government agencies, civic organizations, corporations, and citizens—in all aspects of the security plan. “It was a pretty big evolution in our own thinking, to be able to put community resilience front and center,” Nicole Lurie says.

Since March, 2011, when Obama issued a directive on national preparedness, FEMA has embraced a similar approach to community resilience. “Community-engagement” pilot programs funded by the Centers for Disease Control and Prevention have been launched in Los Angeles, Chicago, New York City, and Washington, D.C. “There’s always been a big focus on classic infrastructure in mitigation,” Alonzo Plough, the director of emergency preparedness and response for the County of Los Angeles, says. “But it’s not just engineering that matters. It’s social capital. And what this movement is bringing to the fore is that the social infrastructure matters, too.”

Sandy revealed serious flaws in all forms of infrastructure in New York and New Jersey. But it also turned up surprising reserves of strength. When I visited Rockaway Beach in mid-November, residents complained about the slow pace of recovery. The power was out. The gas was off. Phone service was spotty. Trains weren’t running. Sewage water from the flooding covered the streets. Still, there were some bright spots. The Rockaway Beach Surf Club, which opened in March, in a converted auto-repair shop beneath the El on Beach Eighty-seventh Street, transformed itself into a temporary relief agency when two of its founders returned there after the storm, posted Facebook updates inviting friends to join them, and watched more than five thousand volunteers come to help. It became the main community organization, providing food, cleaning supplies, camaraderie, and manual labor for nearby residents. The surf club’s neighbors, including blue-collar families and poor African-Americans who, months before, had worried about how the club would fit into the community, joined in and benefitted from the organization.

Ofelia Mangen, a thirty-year-old who lives with her younger brother in a row house on Beach Ninety-second Street, joined the surf club last summer and spent many nights there volunteering with neighbors and friends. “I brought flowers, bartended, worked the door—whatever was needed,” she told me, as we walked down Rockaway Freeway on a mild day in mid-November, past sanitation trucks, police cars, and sidewalks cluttered with debris. “I’ve just kept doing whatever is needed since the storm hit. But now the needs have changed, and there’s obviously a lot more of them.” Two weeks had passed since the superstorm, and residents had no power, gas, heat, or hot water for bathing. Stores, restaurants, pharmacies, and gas stations were closed. Trains were inoperable.

Mangen, a graduate student in educational design at New York University, has a steady disposition. She’s slim but sturdy, with curly brown hair, thick glasses, and a strong, deliberate voice. She had a plastic crate for carrying things and was dressed for manual labor: black ski cap, black puffer jacket, black arm warmers, cargo pants, and hiking boots. “The sidewalks are still coated with sewage, and there’s dangerous shit everywhere,” she warned.

We began at her place, which, like all the houses in the area, sustained major flood damage. (The garage door showed a watermark about four feet above ground.) Several boxes of family photographs and a recently restored 1965 Ford Mustang belonging to the homeowner’s son were among the casualties. We took supplies from Manhattan to a café where the staff was feeding relief workers, and then walked to the compost garden that Mangen helps run and inspected the soil, which had been drenched by contaminated floodwater. She instructed two arborists, who had arrived from Tennessee the night before, on how to prepare a fallen tree so that neighbors could use it as firewood, and offered respirator masks and large garbage bags to a worker from Illinois who was removing water-damaged drywall next door. Then we headed back to her street. A fallen tree rested ominously on the roof of a two-story apartment building on the corner.

Mangen spotted Junior, a neighbor who works as a contractor, parking his van across the street from us, and she led us to the apartment building so that we could see if anyone was there. “Hello,” she shouted, and then banged on the door a few times. “Anybody home?” A young brown-skinned woman peeked out from the second-floor window, beneath the fallen tree. “Are you O.K. up there?” Mangen asked. “Do you need anything?”

“Juice,” she answered. “For the baby.”

We returned to the surf club, where residents, many with shopping carts, lined the sidewalk, putting in requests for food and supplies and waiting while volunteers fetched them. Mangen introduced me to Brandon d’Leo, a sculptor, and Bradach Walsh, a firefighter, who were directing the club’s relief efforts, and they enlisted me in the search for volunteers to meet their neighbors’ most pressing needs. “You’re from a school,” d’Leo noted. “Do you know anyone who teaches plumbers or electricians? We can’t get power restored in our homes until we’ve passed an inspection by someone with certification.”

When Mangen returned to her neighbor’s apartment to deliver the juice, the woman came down to greet us. She held an infant, and appeared to have a painful sore on her lip. “Can we get you anything else?” Mangen asked. The woman shook her head, but hesitantly. “Listen, there’s food at the surf club down on Beach Eighty-seventh,” Mangen told her. “It’s just a few minutes from here. And there are places giving out medicine now, too.” The woman smiled shyly, thanked her, and returned to her dark apartment. A few minutes later, walking back to her place, Mangen had a thought. She called the arborists from Tennessee and asked them if they could take on another job. Soon afterward, the tree resting on her neighbor’s rooftop was removed.

Thousands of people whose homes were damaged by Sandy live in neighborhoods that lack strong support networks or community organizations capable of mounting a large relief effort. They tend to be poorer and less educated than typical New Yorkers, with weaker ties to their neighbors as well as to political power brokers. Since Sandy, Michael McDonald, who heads Global Health Initiatives, in Washington, D.C., and worked in Haiti after the 2010 earthquake, has been coördinating relief efforts by volunteer groups, government agencies, corporate consultants, health workers, and residents in vulnerable areas, particularly in the Rockaways. McDonald calls the network the New York Resilience System, and he’s convinced that civil society will ultimately determine which people and places will withstand the emerging threats from climate change. In December, I watched him chair a meeting of network participants—they included representatives from New York Cares (the city’s largest volunteer organization), the accounting and consulting firm PricewaterhouseCoopers, the New York City Department of Health, and the state Attorney General’s Office. “What’s actually happening on the ground is not under an incident command system,” he told me. “It’s the fragile, agile networks that make a difference in situations like these. It’s the horizontal relationships like the ones we’re building that create security on the ground, not the hierarchical institutions. We’re here to unify the effort.”

Whether they come from governments or from civil society, the best techniques for safeguarding cities don’t just mitigate disaster damage; they also strengthen the networks that promote health and prosperity during ordinary times. Contrast this with our approach to homeland security since 9/11: the checkpoints, the bollards, the surveillance cameras, the no-entry zones. We do not know whether these devices have prevented an attack on an American city, but, as the sociologist Harvey Molotch argues in “Against Security,” they have certainly made daily life less pleasant and efficient, imposing costs that are difficult to measure while yielding “almost nothing of value” in the normal course of things.

“We were making some progress on climate-change adaptation in the late nineteen-nineties,” Klaus Jacob observed. “But September 11th set us back a decade on extreme-weather hazards, because we started focussing on a completely different set of threats.” Effective climate-proofing demands more intelligent design. It should provide benefits not just when disaster strikes but day to day, like Singapore’s Marina Barrage, which created new waterfront, parkland, and exhibition spaces, or like a smarter power grid, which helps reduce energy consumption in all weather. That’s true of the low-tech and the no-tech measures. Auburn Gresham’s advantages over Englewood aren’t restricted to mortality rates during a heat wave.

It’s a cause for regret that we’re not responding to the challenges of climate change with the same resources we’ve devoted to the war on terror. As long as the threat from global warming seemed remote and abstract, it was easier to ignore. Now climate change is coming to mean something specific, and scary. “Even on a clear day a hundred years from now, the water will be where it is today under storm-surge conditions,” Jacob said. More heat waves, wildfires, hurricanes, and floods are to be expected. We are entering an age of extremes. “We can’t just rebuild after every disaster,” Jacob continued. “We need to pro-build, with a future of climate change in mind.” ♦