New York city girds itself for heat and rising seas

“Engineers want to know precisely,” he says, “when it will happen and how much it will be.” From those predictions, he says, cost-effective adaptation strategies can be developed.

“Adaptation doesn’t take a wholesale plan,” Heath says. “It has to become part of an agency’s working philosophy. Once you recognise climate change as a risk to your infrastructure, then you take it into account in all of your designs and operations. You do it facility by facility.”

In a city the size of New York, says Heath, where a capital expenditure plan ideally projects needs and costs into the next century, an agency might evaluate a facility only once in five, 10, or even 20 years. So the changes made, such as those new pump motors, have to go beyond resolving immediate needs.

Should measured, gradual, and in situ steps prove insufficient, more radical - and expensive - proposals have been made. The most extreme of these would be to deal with the fact that the shape of New York City’s southern shoreline and harbour entrance - the geography that made it such an amenable port - acts, during a hurricane, to funnel winds and storm surges towards the city.

To counteract increasingly high storm surges, proposals have been made to construct one or more solid barriers across the entrance to New York harbor. The barriers - sea walls that allow water and ship traffic to flow through during normal tides but that can be closed during storms - might also protect New York’s major airports - LaGuardia, Kennedy, and Newark - whose runways are now just barely above sea level. They would also protect wetlands, beaches, and salt marshes faced with severe storm erosion. Storm surge barriers already protect the port cities of London and Rotterdam, for instance, although increasing sea levels may soon make these earlier barriers obsolete. Rotterdam’s climate change adaptation strategy calls for building a half-dozen new storm barriers.

While storm surges and flooding might require the most drastic adaptation measures, Freed says that the most chronic effect of climate change on New York will be increasing temperatures. Like cities around the world, New York will face the threat of rising death tolls from heat waves, the result of global warming combined with increasing and ageing urban populations. Counteracting the heat island effects of asphalt and concrete (summer temperatures in the city can be ten degrees higher than outside the city) will require incremental efforts. Adaptation measures already begun include new land-use requirements for open space, car-free zones, tree planting, and developing green spaces around parking lots and even on rooftops.

Rising temperatures will also worsen air quality. The city is seeking to institute congestion pricing to reduce the number of cars crowding its streets. It has begun efforts to cut back its own local emissions and energy consumption. These adaptation efforts will, it’s hoped, also serve to mitigate climate change effects. They may also bring cost savings. The city projects that its energy conservation measures will save billions over the next decade.

Adaptations not subject to engineered solutions may be far more difficult to devise and implement. The threat to the city’s Catskill Mountains water supply from extended droughts and heat waves, as well as from severe storms, will require a range of adaptations, from monitoring and metering water, to protecting watershed lands and forests.

Heath points out, for instance, that the amount of water flowing into the reservoirs declines when trees in the forests that surround them are in full leaf. Longer growing seasons would mean substantially less water running into the reservoirs. The shortfall could be compounded by predicted long periods of drought that would further reduce flow and increase evaporation. On the other hand, Heath says that severe storms would create turbid runoff and could introduce pathogens into what is still an unfiltered water supply system. For the city, this means increasing stream and land use management efforts far north of the city limits and seeking restricted development along its watershed lands and forests.

New York City’s problems are not unique. Climate change presents complex and costly challenges to coastal cities around the world. London, like New York, recognises that rising temperature will be its most urgent problem. It, too, is hoping to manage its heat island effect, implementing new land planning measures, including greening roofs and open spaces. London is encouraging the adaptation of building codes to minimise the need for air conditioning and to make it efficient and clean.

In Rotterdam, along with creating green roofs, the city plans to turn flood control barriers and levees into waterfront parks and turn water diversion canals into cooling waterways and “water plazas” within the city itself.

Adapting to climate change will be more difficult in cities in India, Asia, and Africa where infrastructures are already stressed by overpopulation and poverty, and where rising temperatures may bring increased risks of disease. Low-lying Bangladesh, which is especially susceptible to sea level increases, has proposed a $4.35 billion adaptation program. What New York City now has that most of these other cities don’t, is a local model of climate change all its agencies can work from. But if the projections are wrong? If the world’s seas rise more rapidly than predicted by the IPCC and NPCC? Then, the result may be more than just a fantastic animation.