This is a collection of letters to the editor of the Washington Post and blog posts in response to “Hot World? Blame Cities” by Joel Kotkin and Ali Modarres. View our blog entry.
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I’m glad Joel Kotkin and Ali Modarres bring up the subject of cities and global warming (Hot World? Blame Cities, October 15). Automobile-oriented, sprawling development is one of the chief causes of greenhouse gases, according to a new book sponsored by the Urban Land Institute called Growing Cooler. The research is clear and overwhelming: suburbs produce significantly more CO2 on a per capita basis. That’s why European nations, with more compact communities and more urban lifestyles, generate half as much greenhouse gas per capita as the US. Any effort to significantly reduce greenhouse gases will fail if it doesn’t curb sprawl. More sprawl means more vehicle miles traveled, which overwhelms efforts to make cars more efficient.
Robert Steuteville, editor of New Urban News
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In their op-ed article “Hot World? Blame Cities,” Joel Kotkin and Ali Modares quote me as the kind of person calling for a wholesale withdrawal from suburbia in response to global warming. As a former mayor, I admit I value cities and appreciate their energy performance. But many suburbs enjoy strong environmental performance as well, if they are walkable, allow mixed-uses, and particularly if they are served by transit. We in the new urbanist movement work intensely to make suburbs more livable, valuable and sustainable. The authors take down a straw man of their own creation.
They also advance the notion that cities are to blame for major climate problems. Kotkin and Modares admit they don’t have any evidence that says the urban heat island effect is a source of global warming. The “urban heat island” effect is local and is addressed through measures such as green roofs, more parks and less parking lots.
A scientific consensus says rising carbon emissions are raising the earth’s temperatures. Personal cars and trucks account for 20 percent of U.S. energy-related greenhouse gas emissions and these totals are rising as people spread out and drive more miles. The average resident of a walkable, mixed-use section of a suburb like Bethesda drives about 33 percent less than the average person in a half-as-dense, auto-dependent exurb like Woodbridge, according to the study just released by the Urban Land Institute and Smart Growth America entitled Growing Cooler. In Manhattan, the amount of driving is much lower still.
With the U.S. needing to replace 70 million housing units over the next 30 years and top demographer Arthur C. Nelson of Virginia Tech University predicting a fast-rising market for smaller dwellings in compact neighborhoods, there’s a great opportunity to embrace a convenient and effective global warming remedy – in suburbs as well as cities.
John Norquist, president of the Congress for the New Urbanism and former mayor of Milwaukee
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Joel Kotkin is right that the urban heat island effect can increase local temperatures and thereby cause people to use more air conditioning. He is way off base, however, to blame cities for climate change and argue that spreading development over more of the planet is the solution.
The Nobel-winning Intergovernmental Panel on Climate Change has stated that “urban heat island effects are real but local, and have a negligible influence” onglobal climate change. Some climate change deniers also have claimed that localized heat islands have tricked us into believing the planet is warming. This claim, too, has been refuted and rejected by the scientific community.
Recent market trends show that people are once again drawn to living in convenient, urban locations with jobs and activities nearby. If this demand can be met as the nation continues its rapid growth, it will help the planet, as noted in the new book Growing Cooler: The Evidence on Urban Development and Climate Change. Both transportation and buildings consume less energy in compact settings, where people have more options for getting around or avoiding travel.
In an age of rising gas prices, Kotkin’s bid to force people to live far from cities, in areas where they are dependent on cars, is no help either to individual Americans or the planet.
David Goldberg, communications director for Smart Growth America
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The authors mislead readers about the causes of global warming.
While pavement does create “heat islands,” that phenomenon is not confined to downtowns. Some of the worst offenders on a per-acre basis are the giant parking lots that surround suburban Wal-Marts and malls. For confirmation, walk across one on a July afternoon.
Moreover, the contribution of heat islands to global warming is dwarfed by that of vehicle traffic. Transportation contributes a third of US carbon emissions and its share is growing. We must strengthen cities and suburbs in ways that allow us to spend less time in our cars, but this won’t happen if we continue to scatter the fragments of our community willy-nilly across what’s left of our countryside.
Cities reduce warming emissions by using existing infrastructure, putting people, jobs, and services closer together, and facilitating walking and mass transit. In the suburbs, concentrating more growth around transit stations in walkable, green neighborhoods provides transportation choices and reduces traffic. In both, we can soften the effects of heat islands by integrating more trees, parks, and roof gardens into our downtowns, neighborhoods and, yes, even parking lots.
Both cities and suburbs will benefit — and so will the planet.
Kaid Benfield, director of the smart growth program for the National Resources Defense Council
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From Ryan Avent at The Bellows:
Hot Air
Someone powerful at the Post is a warming skeptic. I don’t know how else to explain the odd collection of lame pieces popping up there in recent months. There was the bizarre Emily Yoffe column, the inches given to Bjorn Lomborg, and the incredibly silly fact checking of An Inconvenient Truth published just this week. And today, the Post uses its valuable op-ed real estates to let Joel Kotkin make the stupidest warming argument I’ve seen in a while. Urban heat islands are the problem! Except they’re not, forcing Kotkin and co-author to concede, “Urban heat islands may not explain global warming.” No kidding! Except why did you spend your first 8 paragraphs pretending that they do?
Because Kotkin hates cities, and that dumb heat island thing was as good a way as any to lead into a long paean to the wondrous suburbs. Kotkin could have written a very sensible and smart piece on how it’s important to make suburbs greener, a theme he mentions in between shots at dense urban areas. Instead he threw scholarship out of the window, as he so often does these days, and decided that sticking his finger in the eyes of the urban elite was more important than contributing something to the discussion.
Ignore Kotkin’s piece. It fails on two huge counts. First, it explicitly ignores evidence that residents of dense, urban areas emit less carbon per capita from energy use and transportation than residents of less dense areas–his silly air conditioning example notwithstanding. Second, it claims that people just want to live in suburbs and not cities, without mentioning at all the way that skewed policy choices favor suburban life. I don’t doubt in the least that many people do like living in suburbs more than in central cities, but if you ignore things like pollution and congestion externalities, transportation funding disparities, wasteful competitive tax regimes, and other relevant factors, you’re just not being honest or serious about population distributions.
But why should Kotkin care about seriousness, when un-seriousness gets him checks from the Washington Post?
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Ecological Fallacy
Joel Kotkin and Ali Modarres‘article of October 14, “Hot World? Blame Cities,” chastising New Urbanists and “greens” for allegedly anti-suburban attitudes rests its sprawling case on references to “academic literature and scientific journals.” The authors must not have read them very carefully, because the articles referred to do not support their contentions.
One reference is an article in New Scientist entitled “Urban heat island,” October 28, 2006. This is a respectable journal that publishes understandable explanations of complex phenomena. The article carefully explains how heat islands are created, notes studies going back to 1820, and on climate change specifically states: “no, the urban heat island effect does not explain global warming.” This is good, since global warming is attributable to the heat-trapping effect of global warming gases such as carbon dioxide, not to the heat effects of cities. Nor are heat islands limited to cities, rather, they occur wherever sufficient mass and insufficient reflectivity and vegetative cover come together, which can as easily be in a suburban or rural area as in a city. There are excellent domestic centers for heat island studies and the short article refers accurately to the proper level at which to mitigate this problem, namely the site and neighborhood, as opposed an entire city or region.
Another reference is an article in Climatic Change, entitled “Estimating the ecological footprint of the heat island effect over Athens, Greece,” January 9, 2007, by scientists at Athens universities. The op-ed claims heat islands cause profound problems beyond city boundaries, and notes that the journal article found that the ecological footprint of the city due to the heat island is 1.5 to 2 times the city area. In the well-prepared article the authors clearly conducted a modeling experiment using 22 temperature monitors across Athens’ 450 square mile footprint, and then used 4 of these monitors to represent the entire area, against one control in an adjacent non-urban area.
No quibble with the measurements, but the op-ed implies this data infers negative effects from density. While the article uses terms such as “high traffic and building density,” this is doesn’t support a causal relationship with temperature. The Heat Island Research Group of Lawrence Berkeley Laboratories finds variations in temperatures from block-to-block, but the measurements taken in the article were from monitors each representing 450/22 or 20.45 square kilometers, with final data from 4 monitors each representing 450/4 or 112.5 square kilometers, respectively.
The op-ed implies that air conditioning causes a large “ecological footprint,”; what the article does is ask, what if all buildings in Athens used portable air conditioners (they note that actual A/C penetration is 11.2 percent) with certain characteristics, used electricity from off-site generators wasting 70 percent of their heat, and then needed to offset the heat and carbon emissions from this use by an area of planted trees. I raise this not to belittle an excellent analysis by the Athens authors, but rather to note that drawing conclusions, as Kotkin and Modarres do, from large-area measurements to accurately represent what goes on within smaller areas, is known as an ecological fallacy.
The op-ed states: “one big problem is that making large buildings green also makes them much more expensive…and less affordable for middle-class and working-class families. Low-density areas … lend themselves to much less expensive and more environmentally friendly ways of reducing heat. It often takes nothing more than double-paned windows to reduce the energy consumption of a two- or three-story house. …A nice maple can cool a two-story house, but it can’t quite do the same for a 10-story apartment building.”
Studies by the US Green Building Council and the New Buildings Institute find the premium for meeting a “LEED-rated” standard is 5 percent and this is quickly paid for by operating cost savings. Neither double-pane windows nor trees are uniquely suburban and most cities’ high densities are achieved at low-rise heights of 3 to 4 stories. Buildings do shade each other, and studies of elevation by the Martin Centre for Architectural and Urban Studies at the University of Cambridge find this urban shading typically diminishes direct solar gain by 21 percent.
To the general assertion equating density with largeness and reduced affordability — studies by colleagues at research institutions find urban form is location-efficient with the combined benefits of proximity and convenience. As dwellings-per-building increase, so do shared walls and infrastructure, lowering unit heating and cooling costs.
As dwelling units per residential area increase, so do the opportunities for co-locating shopping, schools and jobs near where people reside, and as a result, every doubling of density within a region is associated with anywhere from 20 to 50 percent annual reduction in vehicle-miles traveled per household each year. Raising suburban densities from 2-3 units per acre to 8 units or more will support transit startup, and 40-50 per acre supports full urban service. And the more dwellings per neighborhood, the lower the unit costs for necessary heat island mitigation.
None of this suggests that suburbs cannot be built to higher levels of efficiency. Most traditional suburbs were built with an urban layout, much higher levels of street connectivity and pedestrian character, and originally with street railway, elevated or commuter rail service, much of which still exists today. Twenty percent of American households are in such places, on top of thirty five percent or so in central cities, ten percent in rural cities, and perhaps another 10 percent in and around suburban town centers served by mass transportation.
The op ed states: “…short of a crippling fuel shortage …it’s …unlikely that we’ll ever see the widespread success of heavily promoted strategies such as dense, transit-oriented developments or the wholesale abandonment of the suburbs.” Serious researchers such as Dr. Anthony Perl at Simon Fraser University in Vancouver find that peak oil production will occur no later than 2012.
The fuel-efficient cars mentioned get us some of the needed improvement but only location-efficient communities with urban quality and transportation choices including high capacity mass transportation will reduce our dependence on imported carbon-intensive liquid fuels, and on high-price, low-capacity highways. PriceWaterhouseCoopers finds that the top pick among leading institutional investors is mixed use transit-oriented development, driven by changing demographics and proven success. The large number of applicants for the new “LEED for Neighborhood Development” rating suggests marketplace willingness to bring location efficiency to newer suburban areas too.
None of the sources cited support the op ed’s inflammatory contentions regarding cities. This may be an inconvenient truth for the authors, but cities and urbanism are not to blame.
Scott Bernstein, president, Center for Neighborhood Technology and member of the President’s Council on Sustainable Development 1995-2000.
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Foolishness from Kotkin
Mike Lewyn
Excerpt:
Kotkin’s argument is as follows: cities create heat islands. Therefore, suburbs are good and cities are bad. But this begs the question: which kind of cities create heat islands? It may be true that cities are warmer than suburbs. But it is not therefore true that “highly concentrated central cities” are warmer than sprawling, car-depedent essentially suburban cities.
Automobiles contribute to the heat island effect (Heat Island study, page 2) as does paving over vegetation to build parking lots and roads (See this CDC study, page 206). Automobiles and pavement are more common in car-dependent cities; thus, it may be that such cities actually create greater heat island effects than does development of more traditional cities. For example, Houston, one of America’s most sprawling, more car-dependent big cities, has a heat island comparable to that of other cities — hardly the result we would expect if dense cities were hotter than sprawling cities. At any rate, Kotkin doesn’t bother to discuss this issue- to him, all cities are the same.