How location, household size and income impact your carbon footprint

Buy a hybrid car or save up for solar panels? Shop for local produce or choose compact fluorescent light bulbs? It's tough to know which environmentally-friendly changes make the most impact.

New research out of the University of California, Berkeley, shows that who you are and where you live can determine which eco-changes would be most beneficial. Christopher Jones, lead author of the study and a researcher in Berkeley's Renewable and Appropriate Energy Laboratory, told me more about the findings last week. Below are excerpts from our interview.

What are the elements of a carbon footprint?

We consider the carbon footprint of everything that household consumes. A carbon footprint is a measure of greenhouse gas emissions required for the production, use and disposal of goods and services. That could be anything from transportation to household energy [to] actual goods and services, products, food, water and waste.

Businesses also have a carbon footprint. There is some potential for double counting there. We're not saying that this is what you're responsible for. We're saying, 'This is the carbon footprint of all your household activity.' We leave it to individuals to determine what they want to take responsibility for. That's an important point. It's easy for people to understand that the fuel they burn in their vehicles [is] something they're directly responsible for. They also feel responsible for their energy, but that is indirect. It's emissions that the company is doing on their behalf. Food is also indirect. Consumers place demand on the economy and the economy provides goods and services to the consumer.

Your study found that who you are and where you live makes a big difference in the activities that have the largest impact on your carbon footprint. Talk more about what you found and what it means.

We looked at carbon footprints in 28 metropolitan regions in the United States. We found that the carbon footprint composition varies quite a bit. If you live in California where electricity is produced with relatively clean sources, your carbon footprint from electricity for the average household is only 5 percent of the total carbon footprint of the household. If you live in the Midwest, it could be 25 percent or more. That's a big difference. In California, emissions from transportation are about eight times greater than emissions from electricity. Transportation in California is a much greater opportunity for energy efficiency.

Regardless of where you live, food turns out to be an important part of your carbon footprint. Most of the emissions are in the production of food itself, [such as emissions from fertilizers]. For meat products -- in particular, beef -- a lot of emissions are from methane, which is basically cow burps. The cows digest their food anaerobically and produce methane.

Also, household size and income matter. If you are an upper-income household, it's likely that air travel is a bigger part of your carbon footprint. If you're a lower-income household with a large number of people, food is going to be a bigger part of your carbon footprint. We noticed these patterns of differences in carbon footprints based on location, household size and income.

So we can't all make the same change and get the same result. What do you suggest people do to reduce their carbon footprint effectively?

Luckily, there are some good rules of thumb:

• Transportation - Choosing which vehicle you're going to drive is often the single largest emission reduction you can make. It's the single greatest opportunity. [The typical home with two vehicles will] produce about 10 tons of CO2. Going from 20 miles per gallon to 40 miles per gallon, you can cut that in half. In California, that's equivalent to putting solar panels on your house.
• Location - Choosing where you live is also important, [especially] how far you have to drive to get to where you need to go.
• Food - Americans purchase about a third more food than they eat. They eat about 25 percent more calories than they need for a healthy lifestyle.
• Energy - There are a number of small actions we can take that will lead to emission reduction. Households can hire a professional to do an energy audit. It becomes cost effective. We spend a lot of money on energy.

Talk about the online Household Carbon Calculator.

It's a collaboration with the California Air Resources Board. We've developed a carbon management tool [for Californians]. We also have a national version. By answering three pieces of information -- where you live, how many people are in your home and your income -- you get a good idea of what your carbon footprint is. Then, you can modify it based on your own lifestyle, such as how many miles you drive, your food consumption. It compares you to similar households. You can see how well you're doing compared to other people like you. Then, you can quickly figure out what you can do to save money and reduce your carbon footprint. You can save the data and compare yourself to other people in your community. Everybody who uses the carbon calculator in your city or your county is placed on the page for that community.

The personalized feedback is important, but so is comparative feedback. The way we behave is very much modeled on what other people are doing and what other people might think. That's a big shift we're seeing. People who are leading more eco-friendly lifestyles are increasingly more respected by their peers and community. It sends a signal that you're conscientious. You're taking action.

What motivates you to do this work?

In order to avoid the worst consequences of climate change, ultimately we need to transition to a clean energy economy. That is, getting our energy from renewable sources for our vehicles, for our homes, for our lifestyles. Until we truly have a clean energy economy, individual action can do a lot. There's a great opportunity now for individuals to act before policymakers act. I know most people are concerned about this issue and they're willing to do something about it. They just don't have the right information. There's opportunity now for people to focus on things that are going to make a difference.

What's the next step?

Our goal is to provide sophisticated, transparent and user-friendly information to households, businesses and communities. Our belief is that this information should be widely available and free. Our goal is to help enable programs. We're developing tools and information, but it's really about on-the-ground efforts at the community level. Different populations are going to have different barriers preventing them from taking actions or different motivations. Community-based programs can identify creative solutions to those barriers.

The challenge is scalability. People are willing to take action if you can get personalized, targeted information. But you want programs that will have large impacts and scale across populations. For that purpose, it's good to look at the total potential for each reduction opportunity.

Image: The typical U.S. household dumps 48 tons of carbon dioxide into the atmosphere each year. In this breakdown, blue indicates direct emissions, such as from driving a family car or heating a home. Green indicates indirect emissions, such as carbon emitted by the trucks delivering groceries to a retail store or in the process of growing crops. / Courtesy of UC Berkeley

Photo: Christopher Jones

This post was originally published on Smartplanet.com