What Is A Carbon Footprint, How Big Is Mine, And Why Should I Care?

by Nicola Temple on November 23, 2011

We’ve referred to carbon footprint a lot here on EcoVillageGreen; usually in reference to reducing it. It’s a term one hears a lot in environmental circles. But, what is a carbon footprint?

Essentially, a carbon footprint refers to the measure of carbon dioxide produced by our daily activities.

It refers to the fossil fuels we burn to light and heat our home, to fuel our travel, and to produce the things we buy.

A carbon footprint is usually expressed in terms of some measure of carbon dioxide (e.g., pounds or tons) over some unit of time (e.g. per day or per year).

It can be a measure of an individual’s footprint, or a business, or even the lifecycle of a product.

The carbon footprint can be broken down to two levels of detail. The primary footprint measures the carbon emissions from the direct burning of fossil fuels through energy consumption and transportation. The secondary footprint measures indirect emissions from the whole lifecycle of the products we use. In other words, the emissions involved in the making and breaking of the things we buy.

But, why do we care about our carbon footprint?

There is a natural cycle of carbon. There is carbon in the atmosphere, carbon dissolved in the ocean, carbon as a component of all living things, and carbon stored in ancient deposits in the Earth (fossil fuels). Carbon naturally cycles through these systems and I’m going to save you some reading here and just refer you to this great video that explains the carbon cycle and how humans have affected this cycle.

So, as you can see, we have disrupted the natural carbon cycle and we are putting more carbon into the atmosphere and the oceans, causing global warming and ocean acidification, respectively.

The measure of our carbon footprint tells us how much we are contributing to these emissions.

Experts have suggested that to combat global warming, individuals have to aim for an annual carbon footprint of 2 tons. The average American is said to produce around 20 tons of CO2 each year.

Four tips for selecting a carbon footprint calculator

If you type the terms carbon footprint calculator into a search engine you literally come up with pages and pages of options. So, how do you choose which one to use? I’ve tried quite a few now and here are 4 tips I have when it comes to selecting a calculator.

1 – Location specific – calculators that ask you for where you live have likely factored in some location specific details. At the level of country, the calculator can ask for information in measures you are used to and it can compare your results with the national average. At a more local level, for instance zip code, the calculator may have even factored in things like local energy rates, green energy use, and power generation emissions.

2 – Secondary carbon footprint information – To me, this is critical. I eat a largely vegan diet and I buy local organic food, so if these things aren’t factored into my calculator, I get frustrated. Purchasing habits, food, and lifestyle all make an impact and so the more details that go into the calculation the better.

3 – Meaningful analysis – It’s great to have a single figure at the end of the exercise giving you your annual emissions, but a more detailed and meaningful analysis is what will help you make changes. Some calculators break down your emissions by categories of services, transportation, energy consumption etc. This provides a clear picture of where your biggest impact is.

4 – Option to save – most calculators have this option mainly because they are tied to organizations that want your contact information. However, if this is something you plan on tracking and returning to after making changes in your life, it’s critical to be able save your profile. If you put in the same data to three different calculators, you will likely get three different estimates of your annual emissions. Therefore, if you’re trying to track your progress, stick with one calculator and then at least everything is relative.

Four calculators to look at:

1) Carbon Footprint – this is one of the better ones in my mind.

Features I liked:

  • It has country specific information and then for some places, like the US, it has more local details they use in the calculator, such as electricity generation emissions.
  • There is an option to change the time period for which you’re making the calculation. This could be helpful if you’re trying to compare time periods (for example seasonal differences).
  • This calculator has a great secondary carbon footprint calculator that includes factors such as food preferences, organic produce, and purchasing habits.

Features that could be improved:

  • When inputting the energy usage for the household, the instructions aren’t clear whether you are putting it in for a month or a year – it took me a while to realize it was for the entire year.
  • The options in the secondary footprint calculations were limited for some answers.  For instance, there was an option for ‘eat all organic food’ or ‘eat some organic food’, whereas I feel I’m in the category of ‘eat mostly organic food’.

2) The Footprint Network – another great one, though it’s actually an ecological footprint calculator.

Features I liked:

  • It has a little animation, which can make it fun if you’re doing this with the kids.
  • You can choose to set up a username and password and save your information, or you can just do a quick and dirty calculation.
  • You can enter faster basic information or more detailed (and therefore more accurate) information for each question.
  • It incorporates your recycling practices into the equation.
  • It breaks down the footprint at the end into several sub-headings so you can see where your greatest impact is.

Features that could be improved:

  • It is being developed so there are limited geographical locations.
  • It seems as though based on the questions asked, it would be easy to provide a carbon emissions value as part of the analysis at the end.

3) WWF – The panda people have a carbon footprint calculator too!

Features I liked:

  • They look at the secondary footprint factors such as food and goods and services.
  • Very user-friendly.

Features that could be improved:

  • They ask for your annual air travel in miles flown per year, which most people don’t know off hand, or number of one-way flights, which is very general.
  • The analysis at the end gives you only your emissions in tons per year in comparison to the world and to the US. No more detail than that.

4) The Carbon Diet – this is really a whole other kettle of worms than a calculator, but is worth mentioning anyway. It is a carbon footprint tracker and social networking tool all rolled into one.

Features I liked:

  • You can create a profile for yourself and compare your footprint with other users online.
  • Easy to track progress as you just plug in details every time you fill up with fuel or pay your energy or gas bills.

Features that could be improved:

  • The biggest drawback is that it doesn’t incorporate secondary footprint features into the equation.
what is a carbon footprint

What is a carbon footprint? Oxfam took a literal approach to the question and generated some feet proportional to an average individual's carbon emissions for a number of different countries. CC image courtesy of net_efekt on Flickr.

Reducing your carbon footprint

Almost all of the carbon footprint calculators provide tips and advice for reducing your carbon footprint. However, most tips are general advice and are not specific to your footprint at all. This can be frustrating. I know because the number one tip is usually to drive less. I work from home and my husband bikes. This isn’t relevant for us. But, I guess you just have to sift through and see what advice is relevant for you.

Changing habits that affect your primary carbon footprint are going to have the most impact as they are direct consumption of fossil fuels. In other words, reducing your energy consumption and your travel will take big bite out of your annual emissions.

Other habits can also downsize your carbon shoesize, the first and foremost being a change in diet. Reducing your calories from animal products takes a big chunk out of your emissions. For instance a change to a vegetarian diet (still eating dairy and eggs) reduces average annual emissions by 1 ton of CO2. Reducing the transportation costs associated with getting your food to you is another great approach.

After looking at these calculators, I’m certainly up for the challenge of reducing my footprint. It’s the competitor in me coming out…I can’t help it!

I recommend giving some of the carbon footprint calculators out there a try. It’s fascinating to see how they compare and to see how changes you make to your daily life affect the outcome. Besides, then the next time someone asks you ‘What is a carbon footprint?’ you can not only tell them, you can give them a figure your current footprint…and challenge them to beat you!

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