As Superstorm Sandy reminded us, cities face the dual pressures of increased urbanization and climate change, putting them at risk for storms, droughts, heat waves, and more.
These risks are real and significant. Over 90 percent of cities are on the coast, putting people at risk from sea level rise and coastal storms. Over 300 million urban dwellers live at or close to sea levels. And while only 15 percent of global water basins are water-stressed, almost half of all cities over 100,000 people are in these basins.
Coast of New York City, as seen from Hoboken, NJ. (Photo by: John Dalton.)
Globally, cities are projected to grow by over 2 billion people by 2050. The choices we make today about where and how that growth occurs could reduce or exacerbate risks for cities.
Cities rely on natural infrastructure for vital services, including water supplies, stormwater management, coastal protection, air quality, and cooling. However, many of these functions are not well understood or valued and therefore are not invested in or included in planning decisions. As a result, cities typically turn to traditional civil engineering or "grey" infrastructure solutions, such as sea walls and large water treatment systems, to address environmental risks, despite the fact that natural infrastructure -- a wetland, forest, or floodplain -- might perform the same function at a lower cost, or be integrated into a "grey strategy" for optimal performance and cost savings.
We cannot sustainably support the current pace of human and economic growth without changing the way cities are planned, built, operated, and financed. We must take steps to protect critical ecosystems and incorporate "natural defenses" into urban areas to reduce risk and vulnerability.
New York City is a prime example of how the natural and urban environments can blend together to enable sustainable growth. Through PlaNYC, Mayor Michael Bloomberg's sustainability plan, New York is investing $1.5 billion over 10 years to protect the city's water at its source, enabling the City to avoid constructing an $8 billion to $10 billion water treatment plant. The City is also investing over $1.5 billion as part of its Green Infrastructure Plan to utilize a mix of natural and hard infrastructure to capture rain water and prevent flooding and sewer overflows -- investments that have an equivalent value of $2.2 billion in grey infrastructure. And over $100 million has been committed to preserve and restore the city's 6,000 acres of wetlands, which help improve water quality and mitigate storm damage.
Another good example of an integrated approach is South Cape May, N.J., where The Nature Conservancy worked with three communities to restore coastal dunes and wetlands to reduce flooding. While at the center of Sandy, the restored dunes and wetland system appears to have spared the nearby communities from the kind of flooding they experienced before the restoration was completed.
Other cities are taking similar steps: San Antonio has established a water protection fund and is working with landowners to protect the nearby Edwards Aquifer. Philadelphia is implementing a green infrastructure program that rewards taxpayers for reducing storm water runoff, saving an estimated $8 billion over traditional grey infrastructure. In response to Hurricane Ike, Houston conducted a full review of ecosystem services and developed initiatives to protect coastal areas and increase storm barriers using both grey and natural infrastructure. And The Nature Conservancy is working with more than a dozen cities -- including Nairobi, Kenya; Sao Paulo and Rio de Janiero, Brazil; Bogota, Columbia; and Santa Fe, New Mexico -- to connect funding from downstream water users (such as cities) to conservation activities in the upstream communities that affect water quality at its source (a mechanism called Water Funds).
Nature can and should play an important role alongside engineered solutions in building (and rebuilding) the cities of tomorrow. To increase our resilience, cities need to use all of the tools and options available to them -- including, but not limited to, natural infrastructure. While there are signs that some cities have recognized this, the pace of growth and climate change are too fast to limit ourselves -- and the cost of failing to make sound investments today is just too high.
— Adam Freed is the Director of The Nature Conservancy’s Global Securing Water Program and a Lecturer at Columbia University. He previously served as the Deputy Director of the New York City Mayor's Office of Long-Term Planning & Sustainability.