This post by Rob McDonald originally appeared on The Nature Conservancy blog.
Golden Gate Heights in San Francisco, California. Photo © Daniel Hoherd/Flickr through a Creative Commons license
Zoning is often viewed as a friend of conservation. But could some zoning actually be detrimental to conservation goals?
It may seem almost heresy for environmentalists to argue for more development in certain places. But that’s exactly what I will argue in this blog. Let me explain.
On a recent trip to the San Francisco Bay Area, I saw a worrisome sight I often see in America cities. In North Berkeley, you can be just a few blocks from a Bay Area Rapid Transit station, which offers an easy 30-minute commute into downtown San Francisco.
And yet the neighborhood is single-family, detached homes that house relatively few people. Zoning has made it so, by prohibiting certain kinds of structures (apartment buildings, for instance) that could house way more people.
This is sometimes called exclusionary zoning, when the primary purpose is to restrict further development or change in a neighborhood. It’s a change from (arguably) the original purpose of zoning and building codes, which was to protect public health and safety (by preventing a factory with smokestacks being built next to residential housing, for instance). It’s also massively common in the United States- one study classified 80% of U.S. urban land as having minimum lot sizes that prevent more dense development. On some parcels, that may be quite appropriate, for environmental, health, or safety reasons. But it is striking that 4 out of 5 landowners are prevented from developing more densely, even if they wanted to.
Environmentalists have to tread carefully when discussing zoning codes. We want the government to be able to use zoning codes to protect public health, ensure access to public parks, and protect at least a few parcels of open space in a metro area. We want governments to be able to plan to make cities more walkable, greener, healthier places. So we respect and support strong zoning codes. Yet the massive exclusionary zoning in many cities has restricted housing supply near cities, pushing up prices there and contributing to urban sprawl, and the spread of new low-density neighborhoods in the fringes of urban areas.
One study I worked on in the Bay Area looked at this process. Parks in the Bay Area, while extensive, didn’t restrict the housing supply much, since land protection was overwhelmingly on sites that were either too steep or too wet to support dense development. The main limitation on housing supply was simply the large amount of area restricted by zoning to single family homes.
Suburban single family house development. Photo © Dan Reed/Flickr through a Creative Commons license
The Bay Area is actually denser already than many U.S. metro areas, and regional groups like the Greenbelt Alliance are actively trying to encourage infill development, increasing housing density within the urban footprint of a city rather than expanding the urbanized areas. The Association of Bay Area Governments has mapped places for infill development, and outlines changes to zoning and tax codes that could make infill development more possible. The Metropolitan Transportation Commission has promoted transit-oriented development, to support this infill development. Despite all these efforts, I was struck during conversations in the Bay Area by how controversial infill development can be. Change is hard. It is hard for people to accept changes in neighborhoods they have come to know and perhaps love.
http://blog.nature.org/science/2015/09/30/environmentalists-development-houses-zoning-urban-sprawl-suburbs-conservation/Continue reading the full post here.
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Rob McDonald is a senior scientist for urban sustainability at The Nature Conservancy. He researches the impact and dependence of cities on the natural world, and is the lead scientist for much of the Conservancy’s urban conservation work. He currently leads a global team of scientists mapping where the cities of the world get their water, and evaluating their dependence on ecosystem services and their vulnerability to climate change. He authored the book Conservation for Cities (Island Press) which documents the role green infrastructure can play in the well-being of urban residents. Another major research interest is the effect of U.S. energy policy on natural habitat and water use.
