I don’t know why you think that. Emissions are generally correlated with income and wealth. Urban and suburban households tend to have higher incomes and wealth than small-town and rural households. I expect average household emissions for the 66 largest metropolitan areas are higher than for households outside those areas. Average emissions for rural households may be lower than average emissions for central city households.

Second, for each metro region, it compares households in Census defined “central cities” against those in the rest of the metropolitan region. But densities and levels of transit service vary widely between the different central cities, and also varies widely in the regions outside the central cities.

So what? The average difference between suburban/exurban and central city households is on the order of 10%. So even if the entire population were to live at the average density of our central cities, we’d only reduce household emissions by something like 10% (and household emissions are only about 40% of total emissions, so the reduction in total emissions would be even lower – on the order of 4%). Yes, some central cities have higher densities than others. If everyone were to live at Manhattan-like densities, we’d save much more than 10% of household emissions. But that’s an even bigger fantasy than moving to the central city average density. You just don’t seem to grasp the sheer scale of the transformation in housing and lifestyles that would be required to achieve any meaningful reduction in emissions through densification. You’re talking about a radical transformation in the housing and transportation patterns of hundreds of millions of Americans. You’re talking about abandoning tens of trillions of dollars of worth of existing housing stock and other infrastructrure in suburbs that we have spent the past 60 years building. It’s just not going to happen. The best you could reasonably to achieve over the timescale in which we need to act is a small increase in the average density of housing and a small shift in transportation usage from private vehicles to mass transit. And the emissions reduction would be correspondingly tiny.

This study does not provide a good measure of the potential of compact development and transit to reduce GHG emissions. First, the study doesn’t include households outside the 66 biggest metropolitan areas, and these households can be expected to have relatively high GHG emissions.

Second, for each metro region, it compares households in Census defined “central cities” against those in the rest of the metropolitan region. But densities and levels of transit service vary widely between the different central cities, and also varies widely in the regions outside the central cities. For example, Seattle and Bellevue are both designated “central cities” and get counted in the same bin, but urban form and transit use are very different in these two cities. Most of the new large “central cities” in the U.S. are relatively low density and car-dependent — not the compact development model.

If you want to draw conclusions about the effects of density and transit on GHG emissions, you need to compare regions specifically according to their density and level of transit service. And to understand the full potential, you’d probably have to look outside the U.S. to cities like Copenhagen, where more than a third commute by walking or biking, with the remainder split about evenly between cars and transit.

http://bikeprovidence.org/2009/02/18/part-2-on-copenhagen-transit-policies

In the article linked below, Glaeser doesn’t appear to share your view that addressing land use is a waste of time. The headline — “To save the planet, build more skyscrapers” — sounds like something you’d see in post here on this blog.

http://www.city-journal.org/2009/19_1_green-cities.html

Then what’s the problem? If Americans agree with you that existing zoning laws are bad and should be changed to allow for more compact development, they will be changed. If there is demand for such development, it will be built.

According to Census Bureau data, the nation is still suburbanizing rapidly. Between 2000 and 2006, over 90% of the population growth in large metropolitan areas occurred in the suburbs. Less than 10% occurred in core cities. Many major core cities actually lost population over this period, including Chicago, Philadelphia, Detroit, San Francisco, Minneapolis, Baltimore, Pittsburgh, Cleveland, Kansas City, Memphis, Salt Lake City and New Orleans. See: http://www.demographia.com/db-msacore.pdf.

European sprawl has been very different, more like the 1900s streetcar “suburbs” where cars are actually optional.

I think transit is an “option” for most trips for most Americans. But most Americans prefer to use cars because cars are so much faster, more comfortable, more convenient and more flexible. And so do Europeans. Just like Americans, Europeans have long been shifting away from public transportation and towards more travel by car. For a variety of reasons, the absolute level of transit use is higher in Europe than in the U.S., but the trend on both continents favors cars. See this document on trends in European transportation from Eurostat, the EU statistics agency:
http://epp.eurostat.ec.europa.eu/cache/ITY_OFFPUB/KS-DA-07-001/EN/KS-DA-07-001-EN.PDF

The information from these links tells you that on 35% of Seattle’s land, only single-family homes may be built, whereas multifamily housing is permitted on on only 5% (the rest of the land is set aside for sidewalks, streets, parks, the UW, the Port of Seattle, industrial areas, and the like).

Er, what information from those links tells you that? Can you show us the specific provisions in the zoning code and zoning maps that substantiate your claim?

Your broader claim is “in most places, it’s ILLEGAL to build compact developments.” The zoning codes in Seattle, whatever they are, do not tell us anything about the situation “in most places.” What about other cities and towns in Washington state? What about rural areas of the state? What about other states? Where is your evidence that “in most places, it’s ILLEGAL to build compact developments?”

And if it’s true that there is a large unmet demand for compact development that is being thwarted by zoning laws, why aren’t people voting to change the laws? Laws do not arise spontaneously. They are the product of the democratic process. And why aren’t developers building more compact development in places where it is legal to do so?

Zoning is part of the democratic process; we’ve just realized we were wrong and want to take it back now. Suburbanization was born out of well meaning attempts to give every American family a subsidized home–it’s really quite interesting history and sad for places like Detroit. The subsidies–including highways–continue. Will they forever?

European sprawl has been very different, more like the 1900s streetcar “suburbs” where cars are actually optional.

Read about how zoning works and then look at the link again. If a lot is zoned for single-family housing, then it is ILLEGAL to build multifamily housing on the land. That is what it means for a lot to be zoned for single-family houses only. You can read more about Seattle’s zoning code here: http://clerk.ci.seattle.wa.us/~public/toc/t23.htm and zoning maps here: http://clerk.ci.seattle.wa.us/~public/zoningmaps/zmapindx.htm. The information from these links tells you that on 35% of Seattle’s land, only single-family homes may be built, whereas multifamily housing is permitted on on only 5% (the rest of the land is set aside for sidewalks, streets, parks, the UW, the Port of Seattle, industrial areas, and the like).

Also, you want evidence of changes in consumer preference? How about this article http://www.theatlantic.com/doc/200803/subprime:

Arthur C. Nelson, director of the Metropolitan Institute at Virginia Tech, has looked carefully at trends in American demographics, construction, house prices, and consumer preferences. In 2006, using recent consumer research, housing supply data, and population growth rates, he modeled future demand for various types of housing. The results were bracing: Nelson forecasts a likely surplus of 22 million large-lot homes (houses built on a sixth of an acre or more) by 2025—that’s roughly 40 percent of the large-lot homes in existence today.

Your link states merely that multifamily housing occupies 5% of Seattle’s overall land area. It doesn’t say anything about laws regulating land use. I find your claim that “in most places, it’s ILLEGAL to build compact developments” highly implausible. Can you substantiate it?

In any case, land-use laws, like all laws, are a product of the democratic process. If there were large-scale demand for compact development that could not be met because land-use laws were preventing it, people would vote to change the laws or move to other areas where the laws already allowed it. Sprawl isn’t the result of land-use laws. It’s the result of people wanting bigger housing, more space, and the increased mobility they get from doing most of their traveling by car. All across the country, for more than half a century, Americans have been suburbanizing. Moving out of dense central cities and into suburbs and exurbs. The same trend has been happening in Europe. It’s simply how most people prefer to live. Maybe that will change in the future, but I see no evidence of it.

You write:

I think we “should” and we will build what people want us to build. To the extent that there is demand for compact development, we’ll build it. I don’t think there’s much demand. AND:

I see no evidence of large-scale demand by Americans for compact development, or a willingness to substitute mass transit for travel by car.

You’re wrong when you claim we aren’t building more compact development because there isn’t demand for it. In most places, it’s ILLEGAL to build compact developments. In Seattle alone, multifamily housing is restricted to a ghetto of about 5% of the land. See http://friendsofseattle.typepad.com/blog/2006/08/half_seattles_p.html.

Look, no one is talking about forcing people into compact development. Let the market decide. Let’s deregulate zoning in our urban cores so that development isn’t as constrained by the unit-density and height limitations included in our current codes. If buyers and renters want to live in compact development, then at least developers will have the legal wiggle room to build compact development.