Carbon emissions are released every time fossil fuels are burned or greenhouses gasses are released into the atmosphere, the effect of which contributes to global warming.
Fossil fuels are also burnt at various stages in the process of creating food, products and services for our consumption, as well as direct emissions such as the amount of energy used to heat/cool our homes, the amount of fuel used in our cars, and the number of air flights we take. The total carbon which we as individuals are responsible for is called our carbon footprint.
A variety of carbon footprint calculators are available on the web and each is slightly different. Some focus only on direct consumption of fossil fuels (for example, gasoline for transportation and home heating/cooling) while others try to factor in all aspects of living including percentage of organic and local food consumed, water conservation techniques, size of your home, how many people live in your home, if you practice recycling, and if you use renewable energy.
Of the carbon footprint calculators that I tried, the EPA’s is one of the more comprehensive and one of the easiest to use. Although it does not account for individual air travel it is free and will give you a rough idea of what your annual carbon emissions are compared to the rest of the United States. According to the EPA, the average carbon emissions per person in the United States are about 20,750 pounds per year and much of this is directly related to reliance on automobile transportation and the energy efficiency of automobiles.
But for those who want something more precise and a way to track progress on reducing the carbon footprint, Carbon Account (www. thecarbonaccount.com) asks you to enter specific meter readings including your daily car mileage, details of any flights you take, and specific amount of electricity or natural gas that is used in your home.
Similarly, CO2list.org allows you to download an Excel spreadsheet that will help you track your daily carbon emissions. This is the most comprehensive calculator that I found and it has the added bonus that you do not need to be connected to the internet (once it is downloaded) to use it. This carbon footprint calculator uses metered data on the amount of fuel used, the efficiency of your vehicle, the number of people living in the home (and allows for the fluctuation of residents), and approximates a carbon impact based on your general spending habits.
Regardless of the carbon footprint calculator used, most of them try to assess your impact based on the same type of data. The most important variables relate to energy efficiency of transportation and of your home.