Flagstaff, AZ – All this year, NPR is presenting its series Climate Connections: reports on how people affect climate, and how that changing climate affects people. This summer, KNAU is producing local and regional stories on the changing climate here in northern Arizona. Carbon dioxide is a greenhouse gas that researchers say is contributing to global climate change. And, Americans produce plenty of it. We release cO2 into the atmosphere every time we turn on the lights, use the computer, take a hot shower or make dinner. Now, two biology professors at Northern Arizona University have launched a business to help people determine how much energy they're using - and wasting - and where they can make energy-saving changes. Arizona Public Radio's Gillian Ferris Kohl invited professors George Koch and Bruce Hungate to her home to test her carbon footprint. It is a two human, one dog household.