Research Papers

A Bottom up Approach to on-Road CO2 Emissions Estimates:Improved Spatial Accuracy and Applications for Regional Planning

Conor K. Gately,* Lucy R. Hutyra, Ian Sue Wing, and Max N. Brondfield
Department of Earth and Environment, Boston University


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On-road transportation is responsible for 30 percent of Massachusetts fossil-fuel carbon dioxide emissions, and over 35% of CO2 emissions within the City of Boston. Accurate measurement of these emissions is critical for effective regional planning. We have developed an improved model for characterizing the spatial and temporal distribution of on-road emissions in Massachusetts for the years 1980 – 2008. Our model avoids the commonly used technique of using spatial proxies such as population or road density to downscale emissions from the state-level, which can introduce errors wherever trends in these proxies diverge from trends in vehicle activity. We were then able to characterize the relationship between emissions and population density across all Massachusetts towns since 1980. We find that increasing population density is only associated with declining vehicle emissions in towns where density is already relatively high. In lower density towns, an increase in population density is associated with an increase in on-road emissions. Out results highlight the value of high-resolution data sources for estimating on-road CO2 emissions. These new emissions estimates provide vital benchmarking for future development of transportation planning and policy at the regional and municipal scales in Massachusetts.