Increasing the population density of California's urban areas is a key component of the state's plans to reduce greenhouse gas emissions to 1990 levels by 2020 - but it may not be the most effective strategy, new research at the University of California, Berkeley, indicates.
Although suburbs, with their relatively low densities and dependence on autos for travel, are bigger generators of carbon dioxide than urban cores, the researchers said, "a 10-fold increase in population density in central cities yields only a 25 percent reduction in greenhouse gas emissions."
"That would require a really extraordinary transformation for very little benefit, and high carbon suburbanization would result as a side effect," Christopher Jones, a doctoral student in the UC-Berkeley's Energy and Resources Group and co-author of the report, said in a statement accompanying the study's release Monday.
Trying to increase population densities in suburbs, which several state strategies propose, "appears to be an even worse strategy," Jones said, because it would encourage the development of new, high energy use suburbs further away.
What Jones and his co-researcher, Dr. Daniel Kammen, suggest is that one-size-fits all strategies to reduce greenhouse gases give way to locally designed plans based on local circumstances.
"Cities are not islands," Kammen said. "They exist in a complex landscape that we need to understand better both theoretically and empirically."
Toward that end, the study includes an innovative, interactive Internet tool that allows users to calculate not only the emissions of their own households, but of their communities and breaks down the individual components of those emissions.
The average American household is responsible for 48.5 tons of CO2 each year, and the interactive tool allows users to measure themselves and their communities against that number.
PHOTO: In this photo taken Nov. 2, 2008, apartment buildings crowd the skyline in Chongqing, China. Associated Press/Elizabeth Dalziel