By Tony Davis | Arizona Daily Star
Population growth equals more greenhouse gas emissions. Economic decline sends emissions downward.
Those realities emerged from two studies – one local and one national – showing the state and Pima County’s galloping population growth over the past 10 to 20 years has boosted emissions of carbon dioxide and other greenhouse gases faster than the national rate. At the same time, Arizona and Tucson’s worse-than-average economic bust since 2007, when population started stagnating, dropped emission levels faster than national levels.
Greenhouse gas emissions have been linked by most climate scientists in this country to generally warming temperatures since the 1990s, if not earlier. One study, from the U.S. Energy Information Administration, looked only at carbon dioxide emission trends. The local study from the Pima Association of Governments looked at emissions of CO2, methane and nitrogen oxide.
Here are some questions and answers about the studies from Perry Lindstrom, an economist for the Energy Information Administration, and Leslie Ethen, director of the city of Tucson’s Office of Conservation and Sustainable Development.
