|With current development patterns and a slight increase in fuel economy (business-as-usual), VMT and CO2 rise steadily. Click to enlarge.|
Meeting the growing demand for conveniently located homes in walkable neighborhoods could significantly reduce the growth in the number of miles Americans drive, shrinking the nation’s carbon footprint while giving people more housing choices, according to a team of leading urban planning researchers.
In a comprehensive review of dozens of studies—Growing Cooler: The Evidence on Urban Development and Climate Change, published by the Urban Land Institute—the researchers conclude that urban development is both a key contributor to climate change and an essential factor in combating it.
Under the current business-as-usual development scenario, with sprawling development continuing to fuel growth in driving, the Energy Information Administration (EIA) projects a 59% increase in the total miles driven between 2005 and 2030. This will overwhelm the forecast modest (12%) gains in vehicle efficiency.
|Even under stricter vehicle and fuel standards, the increase in VMT keeps pushing greenhouse gas emissions higher. Click to enlarge.|
Even with more stringent standards for vehicle efficiency and lower-carbon fuels—the Senate CAFE bill for 35 mpg by 2020 and the California Low Carbon Fuel Standard—the rapid increase in driving would overwhelm both the increase in vehicle fuel economy and the lower carbon fuel content. In 2030, CO2 emissions would be 12% above the 2005 level, and 40% above the 1990 level.
Curbing emissions from cars depends on a three-legged stool: improved vehicle efficiency, cleaner fuels, and a reduction in driving. The research shows that one of the best ways to reduce vehicle travel is to build places where people can accomplish more with less driving.—lead author Reid Ewing, Research Professor at the National Center for Smart Growth, University of Maryland
Depending on several factors, from mix of land uses to pedestrian-friendly design, compact development reduces driving from 20 to 40%, and more in some instances, according to the forthcoming book, Growing Cooler: The Evidence on Urban Development and Climate Change. Typically, Americans living in compact urban neighborhoods where cars are not the only transportation option drive a third fewer miles than those in automobile-oriented suburbs, the researchers found.
At the same time, the book documents market research showing a majority of future housing demand lies in smaller homes and lots, townhouses, and condominiums in neighborhoods where jobs and activities are close at hand. The researchers note that demographic changes, shrinking households, rising gas prices, lengthening commutes and cultural shifts all play a role in that demand.
The report cites real estate projections showing that two-thirds of development expected to be on the ground in 2050 is not yet built, meaning that the potential for change is profound. The authors calculate that shifting 60% of new growth to compact patterns would save 85 million metric tons of CO2 annually by 2030. The savings over that period equate to a 28% increase in federal vehicle efficiency standards by 2020 (to 32 mpg), comparable to proposals now being debated in Congress.
Implementing the policies recommended in the report would reverse a decades-long trend. Since 1980, the number of miles Americans drive has grown three times faster than population, and almost twice as fast as vehicle registrations. Spread-out development is the key factor in that rate of growth, the research team found.
The findings show that people who move into compact, “green neighborhoods” are making as big a contribution to fighting global warming as those who buy the most efficient hybrid vehicles, but remain in car-dependent areas.
While demand for such smart-growth development is growing, government regulations, government spending, and transportation policies still favor sprawling, automobile-dependent development. The book recommends changes in all three areas to make green neighborhoods more available and more affordable. It also calls for including smart-growth strategies as a fundamental tenet in upcoming climate change legislation.
The study represents a collaboration among leading urban planning researchers, including Ewing, Steve Winkelman of the Center for Clean Air Policy, Keith Bartholomew of the University of Utah, and Jerry Walters of Fehr & Peers Associates. Smart Growth America coordinated the multi-disciplinary team that developed the recommended policy actions and is leading a broad coalition to develop those strategies further. The US Environmental Protection Agency and the Hewlett Foundation provided funding for the underlying research.