Stopping Sprawl Won't Happen Soon Enough to Fight Global Warming

Policies that encourage density as a way to reduce carbon emissions won't be able to play a significant role in reducing carbon emissions in time to counteract global warming, according to a new report from the National Academy of Sciences.

The change brought on by rapid densification, urbanization and abandonment of sprawl development patterns by 2050 would not be enough to counteract climate change brought on by carbon dioxide emissions, according to the report.

"Urban planners hoping to help mitigate CO2 emissions by increasing housing density would do better to focus on fuel-efficiency improvements to vehicles, investments in renewable energy, and cap and trade legislation now being voted on in Congress, according to the study, released Tuesday. It concludes that increasing population density in metropolitan areas would yield insignificant CO2 reductions.

Even if 75 percent of all new and replacement housing in America were built at twice the density of current new developments, and those living in the newly constructed housing drove 25 percent less as a result, CO2 emissions from personal travel would decline nationwide by only 8 to 11 percent by 2050, according to the study. If just 25 percent of housing units were developed at such densities and residents drove only 12 percent less as a result, CO2 emissions would be reduced by less than 2 percent by 2050."

Full Story: Forget Curbing Suburban Sprawl



Brent Toderian's picture

interesting that on Sept.

interesting that on Sept. 3rd, Planetizen had another article on a study showing the density and smart-growth is key to such things.

I find this study, and its conclusions, concerning on several levels.

First, to assess merely a doubling of the remarkably low density in suburbs across north america, is disappointing. Perhaps its fair as the bar is too low in most places, but the densities necessary to see the real magic of mixed-use, walkable, transit-supportive densities - a fundamental rethinking of the suburban pattern, will involve more than a doubling. It will be "density done well", with well-designed, truly complete comunities... With substantially higher densities. A doubling, could be done as simply as allowing secondary suites in single family homes. If anything, the study seems to suggest the "small measures" being suggested in many suburbs don't go far enough.

Second, to write off issues of pattern and lifestyle, and emphasize technological solutions, seems like the scientific mistake often seen in the past. A more useful perspective is that we of course need both, and that neither will likely get us there. ULI's good document "growing cooler" and many other documents do a good job of showing this. So the study, and the title of the article which seems to write off making improvements to suburbia, is not just wrong, its dangerously wrong. It sends the message that we don't need to change anything too hard - all too convenient.

In truth, planners need to do considerably more than we've done in the past, to be a progressive and persuasive part of the climate solution (or at least, mitigation). I've sat on many panels with leading international climate scientists, who connect the dots between our work and theirs, and so must we, vigorously. Google "eco-density" or check out my blog here on Planetizen, to see how Vancouver is using density, design and land use to reduce our city's carbon footprint over time - and yes, hopefully technology will do its part as well. Even that, though, needs our help - ie our new requirements for all condo buildings to have 20% of parking stalls plug-in-ready.

Holistic approaches and perpectives are necessary.

Brent Toderian
Director of Planning
City of Vancouver

Flaws In NAS Study On Sprawl

It seems to me that there are a number of flaws in the study:

1) It only considers a doubling of density, and greater increases in density are possible, as the comment below says.

2) It does not consider that, in addition to smart growth policies, we could have strong policies to reduce automobile use. It is more feasible to reduce automobile use when densities are higher.

3) It considers how much smart growth could reduce emissions from the current baseline, but it does not consider how much sprawl could increase emissions over the current baseline if we do not have smart growth policies. Other studies have found that, without smart growth policies, increased travelling because of increased sprawl would outweigh all our efforts to make cars more fuel efficient.

4) It does not consider that we should implement measures to reduce ghg emissions in order of cost. There are several negative-cost measures available, which should be implemented as quickly as possible. For example, some energy-efficiency measures such as fluorescent lightbulbs, reduce costs because the saving in energy cost is greater than the increased initial cost; no one says that we shouldn't shift to compact fluorescents because they could reduce only a tiny percent of ghg emissions; on the contrary, they are one of the first measures we will take, because they reduce emissions at negative cost. Likewise, smart growth policies reduce emissions at negative cost, because of initial savings in land costs and long-term savings in transportation costs; and smart growth can let us build neighborhoods that are more livable than conventional suburbs, unlike compact fluorescents lightbulbs, which are no better than incandescent lightbulbs.

Charles Siegel

Study suggests policy reform won't be enough

I think that what this study is suggesting is that small-scale, patchwork solutions - the policy reform scenario - won't be enough. We'll have to start thinking big, along the lines of "the great transition" scenarios:

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