Projected Carbon Dioxide Levels for the Year 2020 in Phoenix, Arizona

Previous studies have demonstrated profound increases to CO2 levels in the Phoenix, Arizona metropolitan area and this increase is linked to anthropogenic sources, including traffic volume, land-use patterns, and human population. These studies all agree that vehicular emission is the largest CO2 source in urban areas. Our goal, therefore, is to predict CO2 levels in the Phoenix area for the year 2020 under different fuel-efficiency-standards scenarios. In February 2002, legislation was introduced to increase Corporate Average Fuel Economy (CAFE) standards for personal vehicles by ∼30%. In this study, we present three scenarios for projected CO2 levels for the year 2020 in the Phoenix metropolitan area. In one scenario, we assume that fuel efficiency remains the same, representing no changes to CAFE standards. In the other two scenarios, we reflect possible changes to the standards: one based on the 30% increase in efficiency as proposed and the second based on a 15% increase in efficiency standards. These scenarios were created through a geographic information system model of current and future CO2 emissions. The model was based on data from current CO2 levels from land use, traffic, and population and projected CO2 levels from the same sources. Results show a decrease in CO2 emissions from soils as a result of land-use conversion from agriculture to urban. Additionally, results show an increase in the CO2 levels for the year 2020 compared with 2000 under the 15% increase in CAFE standards and no change in CAFE standards. Under a 30% increase in CAFE standards, CO2 emissions decreased below 2000 levels.