The Carbon Index is an unofficial rule of thumb that allows a person to make purchase decisions based on minimizing greenhouse gas emission impact. The Carbon Index is a method for making back-of-the-envelope assessments about what the GHG impact was of a particular product or service.
Take food, for example. When you go into the produce section of your local "conventional" supermarket to buy carrots, look at how the carrots are packaged. Are they in a package that uses energy to produce? If the carrots are mechanically packed, how are the packing machines powered? Was it by fossil fuel-based energy?
Where did the carrots come from? If they were grown far away, they had to be transported, most likely in a vehicle powered by fossil fuels. Most likely there were multiple transportation steps, e.g., farm to packing plant, packing plant to market, market to distributor, distributor to store.
How were the carrots grown? Were they fertilized? How was the fertilizer applied? Were they irrigated? Where did the energy come from to power the irrigation pumps? Were they sprayed with pesticides? Were the carrots mechanically harvested and cultivated? What energy source was used to power the cultivators and harvesting equipment? How was the fertilizer and pesticide produced?
Where did the carrot seeds come from? Were they the result of a high energy using, factory based process? Were they genetically engineered? What energy went into producing the genetically engineered seed? Were they planted mechanically?
Now that you've got the carbon index of the "conventional" carrot, go to your local farmers market or organic food store. Do the same exercise with the carrots you find there. The first thing you might find is that carrots might not be in season, and you might not find carrots. If carrots are in season, how does the carbon index stack up with the conventional carrot? If you want to support a low-carbon economy with your purchase decision, what choice do you make?
What the carbon index tells you is:
- Buy locally produced or recycled goods
- Support local manufacturers, using locally produced materials
- Eat locally grown organic foods that are in season
- Think carefully about buying items that have a high carbon index. Use your consumer power to put pressure on manufacturers to produce items with a lower carbon index, i.e., less packaging or recyclable packaging, lower energy processes, use of renewable energy for production, etc.
- Indicate to local merchants that you are interested in having them lower the GHG emissions from their businesses. See if the local Chamber of Commerce will sponsor a "lower your GHG emissions" campaign among members, featuring members who have succeeded in lowering their emissions.
Regarding high carbon index foods, check out conventional meat sometime. Shocking!
Another way to assess the Carbon Index more quantitatively is to look at the "embodied energy" in a product. Here are some links to more about embodied energy and the carbon impact.
http://www.cmit.csiro.au/brochures/tech/embodied/
http://www.northernexpress.com/editorial/opinions.asp?id=192
Here is a table of the embodied energy in building materials in megaJoules (MJ) (1,000,000 Joules) per kilogram (kg) of weight or cubic meter (m3) of volume. A joule is a measure of energy. There are approximately 1054 Joules in one Btu. There are 3415 Btu in one kilowatt-hour. There are 3.6 MJ in one kilowatt hour. In California, there are 0.73 pounds of CO2 emitted for each kilowatt hour, so there are approximately 0.2 pounds emitted per MJ of electric energy used. An example from the table is cement. The embodied energy in cement is 15,210 MJ per cubic meter. That means that each cubic meter of cement produced results in the emission of almost 3100 pounds of CO2!
If you look at the embodied energy in cement that is used, it is even higher. The cement is transported from the manufacturer to the distributor. The cement is handled at the distributor and either mixed or put in cement mixer trucks. Then it is transported to the building site and either pumped or loaded into the construction application. All of the emissions from these processes are added to the original 3100 pounds of CO2 emitted by the production process. In addition, when cement is made, CO2 is given off by the manufacturing process during the chemical reaction that occurs when the limestone is baked.
A wild guess, but one that might be in the ballpark is the cement that is in the foundation of your house might have been responsible for the emission of up to 3 tons of GHGs per cubic meter!
