New York, and every other city, was built with certain climactic baselines in mind. This much rain, this much snow, this much heat, this many floods. They form a core set of assumptions about the kind of infrastructure the city needs. Institutions grow up around that set of givens; they are a fixed point in the otherwise tumultuous process of urban governance. Maps are created showing the 100-year flood zones; they show the places that have a one-percent chance of being flooded in any given year.
A map like this might once have been reassuring to those beyond the yellow. Their flood risk seemed minimal. And then came climate change to disrupt the baseline.
Today, the Wall Street Journal reports that fully two-thirds of the houses damaged by Sandy were outside the 100-year flood zone. As their headline put it, "Sandy Alters 'Reality."
Which is a fascinating way to look at it: reality, for some intents and purposes, is a bureaucratic fiction based on the way things were, institutional necessity, and accepted statistical practices. That reality influences housing prices, guides maintenance spending, and sets the boundaries for emergency planning. One reason climate change is going to be so hard and expensive to deal with is that it destroys *that* infrastructure, the soft, spreadsheety kind, not just the brick-and-steel stuff that gets built with that information undergirding it.
New York has to rethink, Mayor Bloomberg has realized. "The yardstick has changed, and so must we," he said in a speech quoted by the Journal. The rest of the country's cities and mayors won't be far behind.
Alexis C. Madrigal is a staff writer at The Atlantic and the author of Powering the Dream: The History and Promise of Green Technology.