This week, New Yorkers learned just how vulnerable their city is to rising ocean levels.
Gale force winds fed fires in Breezy Point, burning more than 80 houses to ash.
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Surging waters and violent winds ripped the Rockaway boardwalk from its moorings and tossed it inland.
Water covered Coney Island, Alphabet City and City Island.
Wind whipsawed the crane erecting the city's tallest apartment building, leaving its boom suspended 1,000 feet in the air.
Salt water surged into every East River subway tunnel between Manhattan and Brooklyn, filling the South Ferry station to the ceiling, corroding equipment, and rendering the system unusable for at least the next several days.
Trees blocked emergency vehicles, stormwater trapped cars, electric lines fell into puddles, and all the lights went out downtown.
"It can get a lot worse than this," said Richard Barone, the Regional Planning Association's chief transportation policy planner. "That's where the concern lies. I think that this was a significant event, but there could be worse storms. This is in no way fearmongering. I'm not even sure we should print something like that."
Yet, though the city had seen the effects of Hurricane Irene, and climate change and its effects on sea levels are well known to people who believe in science, thus far New York City has done little to prepare for storms like the one it just endured.
"Irene and now Sandy have posed some really hard questions for us," said Rob Pirani, the Regional Plan Association's vice president for environmental programs. "And in the past, we've been able to duck these questions, and now we've got to come to grips with it."
As my colleague Katharine Jose reported in February, Mayor Michael Bloomberg's administration has made strides in lessening the city's greenhouse gas emissions, but hasn't done much more than any of the administrations before it to prepare for the effects of the climate change that's already underway.
"I would say three or four years ago there was—and this a general statement, not specific to New York—the emphasis was on mitigation; in other words, reducing our contribution to climate change," said David Bragdon, then the head of the city's Office of Long-Term Planning and Sustainability. "It's only more recently that policy makers are acknowledging what scientists have known, which is that even if we magically stop emissions tomorrow—if we were successful in all these mitigation efforts, there's still effects that are happening already."
Columbia Earth Institute professor Klaus Jacob told Jose that, "I think it's not understood how serious the situation will be in coastal areas and what the costs will be to society at large."
In fact, in some ways, New York City has made the problem worse by encouraging taller and denser development in flood-prone places like the Williamsburg and Long Island City waterfronts, parts of which had to be evacuated this week.
Ideas exist for how to go about protecting at least part of New York from future storm-related catastrophe, but those ideas come with hefty price tags that cause them to lose out against the city's other budget priorities.
How about, for example, finding a way to better seal the city's older subway stations, the ones that have no centralized ventilation systems and rely instead on vents that open up to city streets?
Or, more ambitiously, how about creating what Barone called a "greater redundancy throughout the network," through something like his organization's proposal for a so-called X line connecting the outer boroughs, obviating the need to travel through flood-vulnerable Lower Manhattan?
Along with softer strategies like restoring wetlands, and building oyster reefs and dunes, the city might also consider building surge-mitigating storm barriers, of the sort being used or underway in Stamford, Rotterdam, London, Venice and St. Petersburg.
A SUNY Stony Brook professor has proposed building such barriers near the Verrazano, Arthur Kill and Throgs Neck, for a projected cost of $10 billion, but even that wouldn't make the city invulnerable to another Sandy.
"The idea that somehow we can protect all the shoreline in New York City or in the region is just not possible," said Pirani.
The less-dreamy alternative is even more difficult, politically: to discourage residential development in the city's low-lying coastal areas.
"The perfect use of the Rockaways is the way it used to be used, for summer and seasonal housing, what Jones Beach is used for," said Barone. "It's a barrier island. That's what it is. it's the first natural line of defense for storms."
Pirani said the city should consider "buying people out" who live in particularly flood-prone areas, as New Jersey does with its Blue Acre program.
"I think all these things need to be laid out and considered in light of the damage that we suffered over the last couple of days," said Barone.
"Storms are inevitable," said Pirani. "They were inevitable before climate change, and now it's just gonna get worse."
Bloomberg earlier today wasn't willing to attribute the storm surges to climate change, likely for fear of creating an unnecessary political issue by engaging climate-change deniers.
But Governor Andrew Cuomo went right ahead and said it, just about.
"Going forward, I think we do have to anticipate these extreme types of weather patterns," said Cuomo. "And we have to start to think about how do we redesign the system so this doesn't happen again. After what happened, what has been happening in the last few years, I don't think anyone can sit back anymore and say 'Well, I'm shocked at that weather pattern.'
"There is no weather pattern that can shock me at this point. And I think that has to be our attitude. And how do we redesign our system and our infrastructure assuming that?"