SalvaEco

By Dr. Lisa Moore, Environmental Defense scientist. (Cross posted from Climate411.org.)

Photo: Green OptionsLast week, Yahoo! launched a new site that can calculate how much your carbon dioxide (CO₂) emissions go down when you try their energy saving tips. It's fun to use, and I especially appreciate the snazzy interactive features because I know how hard people worked to build it. My colleagues and I provided the Yahoo! design team with the data they use in their calculations.

I hope you'll visit the site to see how simple changes in your house and car can save energy and lower emissions. But first, let me take you behind the scenes to the complicated world of carbon calculation.

• Which emissions do you count? For the Yahoo! calculator, we focused on emissions from home energy use, personal driving, and commercial aviation. We could make solid estimates of average emissions from these activities, and there are easy steps individuals can take to reduce those emissions. These three activities account for 9.4 tons of CO₂ per person per year, which is about half of the total CO₂ emissions per person in the U.S. Some people also refer to the emissions attributable to a person as his/her carbon footprint.
• How do you count those emissions? Greenhouse gas emissions are often higher when you consider gases other than CO₂, but non-CO₂ emissions can be difficult to calculate. Many carbon calculators ignore all non-CO₂ emissions. The Yahoo! calculator includes non-CO₂ gases for flying and dietary choices.
• How much information from the user? The more information I have, the better job I can do calculating your baseline emissions and your savings. What's your current average annual electricity consumption? What state do you live in? How long do you keep each of your light bulbs on every day? What make and model are your appliances? Obviously that approach can get ridiculously cumbersome to users. So instead we often use national averages.
• Do you include regional differences? Some factors, such as the amount of CO₂ emitted per kilowatt-hour of electricity, vary enormously from state to state. The national average emissions rate is 1.34 pounds of CO₂ per kWh. But in North Dakota it's 2.24, and in Vermont it's a clean 0.03! We accounted for these differences in our calculators on www.fightglobalwarming.com; Yahoo! uses the national average.

Designing a tool like this involves a lot of interesting discussions and decisions (and headaches from boring federal reports like the EPA's emissions inventory [PDF]), but the end result is very useful. Americans have a huge impact on global warming, there are many things we can do to make a difference.

So click around the site, get a sense of which changes will have the biggest impact, and pledge to do something. Did an item on the list surprise you? What have you already done? What do you plan to do next?