Nov. 27 (Bloomberg) -- As New York looks to the future after Hurricane Sandy, it must remember a great paradox of cities. The world’s urban agglomerations are often particularly vulnerable to natural and man-made disaster, yet they are also especially well-suited to defend their space.
Cities from New York to Mumbai are often built on continental edges, which can be dangerous precipices. At the same time, New York can shield itself in a way that far-flung exurbs can’t by building costly defenses, such as sea walls, that can protect against all but the fiercest storms.
For most of human history, water-borne transport has been vastly cheaper than movement over land. To reduce transport costs, we built our cities on waterways.
After the Arab conquests of the 8th century, the Mediterranean became a “Moslem lake,” and Europe turned inward on itself. Its cities were built on inland waterways, such as the Danube and the Rhine, far from the Atlantic or a continental divide.
As Europeans grew stronger, with better boats and bolder ambitions, they spread themselves across oceans and continents. The ports of Holland, the world’s first great maritime urban nation, faced the Atlantic and the threat of rising sea levels. Dutch cities from New Amsterdam to Batavia (New York and Jakarta) were right on the ocean, so that ships could more easily carry goods to and from the Old World.
The British East India Company, which followed the Dutch to intercontinental trading eminence, was an even greater city builder. Tens of millions of people now live in these former trading settlements -- Singapore and Mumbai and Kolkata and Karachi -- and the vicissitudes of the sea put them all at risk.
Since coasts often coincide with tectonic plates, many cities also face the risk of earthquakes. Karachi and Kolkata are both near fault lines and have experienced tremors this year. Cities on the Pacific Ocean -- east (Tokyo and Manila) and west (Valparaiso, Chile, and Los Angeles) -- are particularly vulnerable.
The transportation-related advantages of sea coasts have declined enormously over the past century, and one might have expected humanity to move inland. Yet coastal cities continue to exert a powerful pull. The U.S. is an increasingly coastal nation, as people choose either milder temperatures or the enduring productivity of our historical metropolitan masses, such as New York. The cities of Asia, predominantly on the coasts, have also expanded mightily as once-poor nations enrich themselves through urbanization.
Eleven years ago, the terrorist attack on the World Trade Center exposed the vulnerability of cities to man-made assaults. Many worried that they would empty out as people fled in fear of future strikes.
In that moment of vulnerability, the economist Jesse Shapiro and I looked at the evidence and noted that cities could be safe harbors as well as targets. An original advantage of cities is that they are compact spaces that can be walled off against marauders. An example is London, which, facing the threat of Irish Republican Army attacks, guarded its dense streets with a “ring of steel” including surveillance and concrete barriers.
It is also far easier to imagine building sea walls to protect the geographically limited area around cities than to cover a sprawling coastline.
I am no civil engineer and have no opinion on whether New York City should protect itself with massive walls or with less-expensive, less-imposing defenses, but the city needs to shield itself, and sea walls provide that barrier. The Dutch Delta Program has spent billions to protect the Netherlands, largely successfully.
Sea walls aren’t perfect, as Japan learned in 2011 when the tsunami came crashing over barriers that were meant to protect 40 percent of the country’s coastline. That experience didn’t prove that walls are useless. Rather, it showed they need to be quite high to be effective and that countries should take other sensible safety steps, such as putting nuclear reactors on high ground.
Sea walls are expensive. One recent estimate is that they cost $35 million per mile and require maintenance that costs from 5 to 10 percent of that amount per year. At such a price, protecting the entire mid-Atlantic region would be prohibitively expensive, yet defending New York City would be affordable. A great wall running from Sandy Hook in New Jersey to the Far Rockaways would cost less than $500 million based on that estimate.
Nothing in New York comes cheaply, however, and I suspect that the estimate by the Dutch water-risk expert Jeroen Aerts that it would cost $10 billion to build two barriers -- one between Sandy Hook and the Rockaways and a second at the north end of the East River -- is far closer to the mark. Aerts himself suggests a $17 billion solution with three great walls, and says that an extra $15 billion might be required in added coastline protection.
Aerts’s total of $32 billion would be roughly half the city’s annual budget. But the costs of Hurricane Sandy also ran in the tens of billions. If the alternative is giving up on lower Manhattan, which has hundreds of billions of dollars’ worth of property and infrastructure, the price looks downright cheap. If the Netherlands can build a wall system that protects an entire country that lies below sea level, then New York City can protect itself.
Who should pay for these defenses? The protected property owners, of course. There is no reason why New York should look to the federal government in Washington for this spending.
The city has the money to pay the bill, and it should champion the principle that we only build sea walls or other barriers when the people who are protected pay for them. This helps ensure that the benefits justify the costs. We don’t want to go further down a path where every hamlet on the Eastern seaboard feels it has a right to federally financed storm protection.
Sea walls may not be the answer, but any solution is sure to require huge public expenditures. This highlights another central point about cities: They need strong, effective governments.
Exit polls found that Mitt Romney, an advocate of laissez-faire economics, received only 29 percent of the votes in big cities, while President Barack Obama, who believes in big government, won 69 percent of urbanites’ votes. That pattern makes sense, since people in vulnerable cities need government more than people in far-flung rural areas do (even though the latter often get more per capita in federal subsidies).
Economist Matthew Kahn of UCLA has studied the death tolls from natural disasters. He found that where governments are more capable, fewer people die. This makes me worry about the fate of cities in the developing world that are just as subject to natural disasters as New York is but have governments far less capable of taking effective precautionary measures. Kahn has predicted that cities will be able to defend themselves against the changes associated with climate change. While I am far less certain about Karachi, I am optimistic enough to think he is right about New York.
For my confidence to be validated, however, New York needs to spend billions to defend its vulnerable real estate. We have to stop denigrating mega-projects and resurrect the spirit of the city’s master builder, Robert Moses. If it does this right, New York can again provide a model of safety amid threatening storms for the cities of America and the rest of the world.
(Edward Glaeser, an economics professor at Harvard University, is a Bloomberg View columnist. He is the author of “Triumph of the City.” The opinions expressed are his own.) Read more opinion online from Bloomberg View. Subscribe to receive a daily e-mail highlighting new View editorials, columns and op-ed articles.
Today’s highlights: the editors on the need for a Palestinian victory at the UN and on an emerging fiscal-cliff compromise; Noah Feldman on Egypt’s power struggle; Jeffrey Goldberg on how the Palestinians could gain independence; William Pesek on Japan’s next prime minister; Ramesh Ponnuru on Republicans’ misguided plans for candidates; Tim Judah on Yugoslavia’s lesson for separatist movements.
To contact the writer of this article: Edward Glaeser at email@example.com.
To contact the editor responsible for this article: Katy Roberts at firstname.lastname@example.org.