Which is the best carbon footprint calculator?

http://www.zmescience.com/wp-content/uploads/2007/11/eco-footprint-image_sm.jpgI was recently asked about carbon footprints, and how we can reduce our environmental impact to a genuinely sustainable level. The problem being, whatever you enter into the calculators, and whatever actions you take, it’s still practically impossible to get your footprint to the level of one planet living. And one planet living has to be the ultimate goal, rather than a 20% reduction by 2012, as the government is currently aiming for.

We want to live in a way that isn’t borrowing from the future, but we know we’ve done all we can on the lightbulb and thermostat front. We’ve thought long and hard about where we go on holiday, and how we get to work. We seem to have done all we can, and still our carbon footprint is higher than it should be.

Part of the problem is that carbon footprints are notoriously difficult to evaluate. There’s no official standard, and different calculators include or exclude different things. Most talk about housing and transport, and usually household appliances, but don’t talk about background activities such as food and leisure activities, or shopping habits. Some work from rough estimates, others demand accurate figures taken from your gas bills. And then there’s the presentation of the questions, and how many choices you get and how precise you can be.

So, it being a rainy day, I’ve tried out a number of different carbon calculators. In order of good news to bad news, here’s how many tonnes of CO2 I am responsible for every year.

Google: 1.54
ActonCo2: 1.72
MSN: 1.8
BP: 2
Carbonfootprint.com
: 2.97
Clevel: 3
Bestfootforward: 5.3
WWF: 9.31

In other words, nobody has any idea how much carbon I am responsible for.

  • The first few figures are ridiculous. As a human being I hit 0.5 tonnes per year just by being alive and breathing.
  • Google asked me if I had a car and I said no, and it seems to be assuming that I therefore do not travel at all.
  • BP asked me if I took baths or showers, which is barely relevant in CO2 terms. They didn’t ask if I filled the kettle every time, or how often I ran the washing machine, which other calculators wanted to know.
  • C-level didn’t have an option for anyone who doesn’t own a car, and I jammed their system. I had to lie and say I did, but travelled zero miles in it.
  • C-level also asked me to choose between ‘buy new when needed, moderate shopper, buy most food from supermarkets’ and ‘buy secondhand, grow own food, buy local’. What if you buy secondhand and local, and don’t grow your own food?
  • MSN counted my travel and utility bills, and didn’t ask about anything else.
  • The WWF asked me how many hours I spent on the bus every year, rather than how many miles I travelled. With London traffic that’s a pretty horrendous figure, so that would explain the large figure there. But is it accurate? Who knows?
  • Cows may contribute up to 16% of global co2 emissions, but only WWF asked if I ate meat.
  • None of the calculators deal with consumption in any serious way, but our shopping habits are responsible for a huge percentage of our carbon footprint. Some had one question, usually something simple like ‘how many bags of shopping do you buy in a week?’ Most ignored it altogether.
  • I’ve got a sneaking suspicion some of these are calculating individual footprint, and others household, but aren’t making it clear. Or they’re not sure whether they’re assessing carbon footprint or wider environmental impact.

So, let’s take a guess and say I’ve got a rounded 4 tonnes to my name. Is that good or bad? Clevel say the UK average is 10 tonnes a year, so I’m doing pretty well. MSN say the UK average is 5. Google says it’s 3.5-6.9. I’ve also found figures saying 11 and 12.

The Climate Outreach and Information Network has undertaken a more scientific comparison of carbon calculators. Their winner is Resurgence. It’s probably the most thorough, and also the least flashy. Unfortunately it’ll be too specific for many users, and I didn’t have the information to make it work myself. They also recommend Clevel and MSN.

In conclusion, we need to keep some perspective on carbon footprinting – it’s only a useful tool, not a strict science. And besides, we’re working out individual numbers here, often for the purpose of buying offsets. This is useful, but the most significant impacts on our footprint are often things that are bigger than we are. We need to operate at the level of community, take on systems and institutions, and change our culture, before we’ll really be getting anywhere. There’s the danger that in making sure we’ve done our bit (and some websites are offering a one-off carbon offset for life!) we’re actually ducking out of the real challenge.

But, we do still need to do what we can as individuals. This post is long enough, so I’ll deal with what I think are the biggest priorities in a future post.

If anyone can recommend a better calculator, by the way, please let me know.

  • Update: at last, this has been researched more scientifically. For a much more comprehensive study, see Jack Carrington’s comparison for the Association for the Conservation of Energy.

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17 Comments on “Which is the best carbon footprint calculator?”

  1. Nicholas March 28, 2008 at 11:31 pm #

    I had no idea there were so many discrepancies in carbon footprint calculators. Looks like the science on carbon footprints is a few years behind.

    My advice: don’t worry about counting the carbon, just make lifestyle changes that you know are good! Just like counting calories can be a dismal experience for a food enthusiast, carbon calculators can drag your mind away from the real ideal.

  2. laracheryl March 29, 2008 at 8:48 am #

    Dear friend,

    Your blog is looking pretty good. I would like to have one post in your Blog. I will pay for the post. Can you help regarding this?

    Thanks
    Lara

  3. Phil Whittall March 29, 2008 at 11:53 am #

    Thanks for tackling this one – and the results were, I guess, what I expected – confusing! I imagine, there’s some more mileage for you in writing on this one. The Guardian or Indy should pay you for something like this! I’ll link to this post from my blog – thanks again

  4. MLP May 6, 2008 at 9:52 pm #

    Thanks for reviewing these sites. My students are working on a documentary about global warming and they were wanting to use a CF calculator–your review will help them make an educated decision.

    It is fascinating that there is so much discrepancy between the various sites.

    I like how you made the pop-up snapshots–I’ll have to figure out how to do that.

  5. Christine August 19, 2008 at 6:15 pm #

    Is it OK for me to use your carbon footprint photo on one of Dulwich Going Greener’s posters (for a low-carbon community workshop on 28 September)?

    Thanks

    Christine

  6. Jeremy August 20, 2008 at 8:23 am #

    Sure, I have just sent you a poster-sized, copyright-free version by email.

  7. Jane Hersey August 29, 2008 at 2:40 pm #

    I came across your post as I work for BioRegional, a charity that has recently launched an online footprint calculator. It’s called the One Planet Living Calculator and it can work out both Ecological Footprint and Carbon Footprint. We are also developing an action plan to help people reduce their footprint across all areas of their lives, and we include socio-economic issues such as equity and fair trade in our action plan.

    I agree that the proliferation of calculators is confusing. One of the key issues is that most of them use direct emissions rather than those due to consumption. For example the ActOnCO2 one one just works out exactly what is emitted from your household energy consumption, and your transport if it is in a car or plane.

    However ours takes into account all the emisisons embedded in the production of the goods we buy, the food we eat, the impacts of government etc as well. If you look at our website you can find out more.

  8. Jeremy August 30, 2008 at 8:40 am #

    Hi Jane, thanks for letting us know about that. It looks great and it’s easy to use, and I like the wider scope of the questions.

    I’ve moved house and have a longer commute since I did my comparison, so I will have to repeat the exercise.

  9. harshey April 27, 2009 at 9:21 pm #

    Change.ie has a decent calculator. very comprehensive.

  10. Andreas B September 11, 2013 at 10:45 am #

    A lot of online carbon calculators are unfortunately not very good. I have published a peer-reviewed article in the International Journal of Greenhouse Gas Control evaluating the 15 most popular calculators on the internet (http://www.sciencedirect.com/science/article/pii/S1750583613002168). My analysis documents significant shortcomings of many of the calculators. To remedy this situation, CarbonStory was created as a free calculator meeting all 13 evidence-based principles identified in the research (https://www.carbonstory.org/).

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