Two Views of Cities and CO2
We created maps of Chicago, Los Angeles, and San Francisco. Specifically, these maps show the carbon dioxide emissions from vehicle travel for each metropolitan region.
For each region there are two maps.
Map A: This map shows the CO2 emissions that result from vehicles by a “quarter-section” (a half-mile by half-mile square). This map shows that emission levels are higher in the city center and are lower in the surrounding suburbs and rural areas. Why is this the case? Because more people live in urban areas than in rural areas.
This map shows that the city centers have higher emissions than the surrounding areas. This is not surprising because city centers have much higher populations than rural areas.
Map B: This map uses the same emissions data as Map A but divides the overall emissions by the number of households in any given area. This leads to an interesting result. The emissions in the city center are lower per household than the surrounding areas. This is true for each city.
What can we learn from these maps? Our personal transportation choices can and do impact greenhouse gas emissions and global climate change. Households in the city have easier access to public transportation systems, drive less often or shorter distances, and walk or bike to their destinations. With continued investment in public transit and in walking- and biking-friendly neighborhoods, cities can further reduce greenhouse gas emissions and improve local air quality.
For more information: The data for these maps come from the Location Efficient Mortgage (LEM) model developed in 1997 by the Center for Neighborhood Technology, the Natural Resources Defense Council and the Surface Transportation Policy Project. The LEM model takes into account vehicle miles traveled data by zip code from odometer readings at smog check stations and uses other factors, such as household income and size, vehicle ownership, residential density, block size (a surrogate for pedestrian accessibility), transit routes, and frequency of transit service to predict vehicle miles traveled at the quarter-section level. The LEM model is currently limited to the three regions mapped here.