Study ties sprawl to climate change

Advocacy groups call for compact building patterns

September 21, 2007|By Timothy B. Wheeler | Timothy B. Wheeler,SUN REPORTER

Suburban sprawl is an often-overlooked cause of climate change, a group of urban planning researchers said yesterday, warning in a report that global warming can be slowed only by changing development patterns to reduce the need for Americans to get behind the wheel.

Living in more compact, pedestrian-friendly neighborhoods actually would do more to reduce emissions of carbon dioxide - the chief climate-changing gas - than driving a hybrid car while staying in a typically spread-out suburb, the report asserts.

"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," said Reid Ewing, the report's lead author and a research professor at the National Center for Smart Growth Research and Education at the University of Maryland.

At a news conference in Washington, he predicted that climate change would be the "defining issue" for community planners in coming years.

Funded in part by the Environmental Protection Agency and the Hewlett Foundation, the report was published by the Urban Land Institute, a think tank promoting sustainable communities. Other participants were the Center for Clean Air Policy, another think tank, and Smart Growth America, a group advocating compact development.

The number of miles Americans drive has grown three times faster than the population since 1980, and twice as fast as the increase in vehicle registrations - a trend the report's authors attribute to spread-out development practices.

"We can no longer ignore vehicle miles traveled and the land use that drives it," said co-author Steve Winkelman, manager of the transportation program for the clean air policy center.

Baltimore ranked as only the 64th most sprawling metropolitan area out of 83 in a "sprawl index" developed by Ewing several years ago - compared with Washington's score as the 26th most spread-out. But Maryland commuters yield only to New York State residents for the most time-consuming trips to and from work, Census surveys indicate, while the time area commuters spend stuck in traffic has quadrupled since 1982, according to a separate report issued this week by the Texas Transportation Institute.

The future holds more of the same, the new report's authors predict. The U.S. Energy Information Administration projects total miles driven to increase by 59 percent by 2030, which the report's authors say would cancel out whatever reductions in carbon dioxide might be achieved by improving the gas mileage of cars and trucks.

Building homes and businesses closer together, with more opportunities to walk to work and to shop, could reduce driving by 20 percent to 40 percent, the report argues, depending on the neighborhood's accessibilty to other means of transportation. Residents in compact urban neighborhoods with access to public transportation typically drive a third fewer miles than do auto-dependent suburbanites.

The potential for reducing driving, and carbon dioxide emissions, is great, the report's authors contend. They point to an estimate that two-thirds of the homes and other buildings expected to be needed by 2050 have yet to be built.

Making as much as 60 percent of new growth more compact nationwide could prevent 85 million metric tons of carbon dioxide from being released into the atmosphere annually by 2030, Ewing said. The savings would be equivalent to a 28 percent increase in federal vehicle fuel-efficiency standards to 32 mpg - comparable to proposals now being debated in Congress.

If development patterns can be shifted, the report predicts, U.S. carbon dioxide emissions could be curtailed by 7 percent to 10 percent overall - an estimate Ewing called conservative. Improved energy efficiency and green design in buildings, he said, would only enhance the gains from tighter, more walkable community layouts.

To change longstanding development practices, the authors call for changes in local codes to allow more compact growth mixing homes, shops and offices and for promoting alternatives to driving.

For inspiration, they pointed to a 138-acre redevelopment of an abandoned steel mill in midtown Atlanta into a mix of office towers, hotels, stores, restaurants and thousands of homes and condos. Planners projected that residents of the community, known as Atlantic Station, would drive 35 perent less than if they lived in typical suburban developments.

A federally funded study is under way now to assess the driving habits of the residents who have moved in so far, as well as their physical activity and health.

The report also urges federal legislation to require transportation projects be scrutinized for the greenhouse gas emissions they would produce, and to direct federal funds into promoting green development and regional planning, which could curtail leapfrog, car-dependent development practices.

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