31 Jan 2013
The Flood Next Time
The impact of Hurricane Sandy on New York and New Jersey in 2012 was an example of what educators call a “teachable moment.” The storm got our attention. For some, it helped to connect the dots by showing how hurricane intensity can be a secondary effect of global warming. In the aftermath of the storm, engineers and city planners have been pondering ways to prepare for the flood next time. The New York City Panel on Climate Change has suggested that, by the end of this century, rising sea levels could bring so-called “100 year floods” an even that happens every 25 years or even more frequently. What to do about this? Global warming, it seems, is not just a problem for future generations.
Two major ideas have emerged about mitigation. One school of thought takes its cue from what the Dutch did after the devastating North Sea floods of 1953, which killed more than 1,800 people in the Netherlands. In response, over the next four decades the Dutch spent billions of dollars to create a comprehensive flood defense system, complete with gates that can be closed when seawater threatens. Something like this could be done in New York City with flood barriers built across the Verrazano Narrows Bridge and other strategic locations. Another school of thought favors steps to build up salt marshes and wetlands that could offer protection against storms. The destruction of wetlands was a factor that made New Orleans vulnerable to Hurricane Katrina. Whether by flood barriers or restoration of wetlands, it seems clear that New York will have to mobilize for the flood next time.
But the long-term threat to New York City may not be so much from floods, like Superstorm Sandy, as from the slow, insidious effect of salty water seeping in over time, from groundwater or other rising water levels. Salty water, it turns out, is different because ions create an electric current that promotes rust: “For steel-reinforced concrete, sudden floods like Sandy’s will probably not make too much of a difference. But rising sea levels, driven by global warming, will.” (New Scientist, Nov. 10, 2012, p. 7) The potential impact here is sobering. The US Geological Survey has predicted that a seal-level rise of 3 feet could make groundwater a mile from the coast rise by a comparable amount. That groundwater, as it grows saltier, becomes a long-term threat to cities across the eastern seaboard of the US. Still worse, unlike dramatic and acute effects of a flood, the threat of groundwater corrosion is mostly invisible because it’s underground. Like chronic hypertension, we don’t recognize the threat until we have a stroke or a heart attack.
For me, personally, Hurricane Sandy had an unforgettable impact. I was scheduled to give a speech in the New York area at the time of the storm and my trip of course was cancelled. I live in Colorado now, but I spent much of my life living in and around New York City and I was in daily contact with friends and colleagues who struggled with the impact of the storm. I grew up in Merrick, Long Island, 10 minutes from Jones Beach, and on television I watched the devastation of neighborhoods I knew from childhood. The Hunter College campus building where I worked near Bellevue Hospital, was evacuated after flood damage. Towns on the Jersey Shore where I spent holidays will never be the same. As weeks have passed, all these damaged places have slipped from the headlines. But we need to learn, over and over again, to connect the dots and not forget what has happened.
Is it hopeless to imagine that New Yorkers, and Americans, will be prepared for the flood next time? I’m actually optimistic for a reason I’ll mention briefly here. Not many people have heard about the “Third Water Tunnel” in New York City, but it has lessons for us in terms of long-range planning. Begin with the fact that New York today has some of the finest public drinking water in America, water brought to the City by two massive tunnels from the Catskill Mountains. But those two tunnels are vulnerable: what would happen if catastrophe occurred and the water supply were interrupted? With this possibility in mind, City Fathers in 1954 authorized construction of a third water tunnel, construction which was begun in 1970. The Third Water Tunnel is the largest construction project in New York‘s history. 60 miles in length, it will cost more than $ 6 billion and will not be completed until 2020. Here’s a significant fact: even during the time of New York City’s fiscal collapse and bankruptcy (1975), work continued on the Third Water Tunnel. Here is truly an example of a multi-generational project, an investment in the welfare of future generations.
We will need similar investments for future generations, both to slow global warming and to mitigate the effect of climate change already underway, such as drought and floods. It’s hard to mobilize people’s attention to focus on low-lying Bangladesh or on “possible people” in the year 2100. But when our neighborhoods are devastated, we have a teachable moment. The question is whether we will learn the lesson we’ve been taught.