So…what’s your carbon footprint?

Published Tuesday April 2, 2013 in the New Brunswick Telegraph Journal.

You’ve probably heard of the notion of a personal ‘carbon footprint’.  It’s the grand sum of greenhouse gas emissions produced as a result of your activities, choices and lifestyle.  But do you know what your carbon footprint is, and what it consists of?  Here – hopefully – is a bit of clarity.

Unfortunately, accurately calculating carbon footprints is a complicated affair; it involves a dizzying array of measurements, formulas and assumptions.

But some calculations are very easy, straightforward – and illuminating. 

According to the International Energy Agency, global emissions from fossil fuel consumption in 2010 were 30 billion tonnes of carbon dioxide.  On a per capita basis, that’s about 4.4 tonnes per person.

Canadian emissions from fossil fuel consumption in 2010 were 536 million tonnes carbon dioxide, or about 15.7 tonnes per person.

So the average Canadian carbon footprint is about four times the global average.  If emissions were income, we’d be in a very high tax bracket indeed.

Elements of a carbon footprint
So what makes up that Canadian carbon footprint?  Here are a few components:

Motor fuel: every litre of gasoline burned results in 2.4 kilograms of emissions.  But that figure doesn’t include emissions from drilling, extracting, transporting and refining that gasoline, and then trucking it to the service station where you buy it.  Factor those in, and it’s more like 3 KG/litre.  If you consume 40 litres per week, that equals over six tonnes of emissions per year.  Many Canadians consume a lot more than 40 litres a week. 

Heating oil: every litre of furnace oil burned results in 2.7 KG of carbon dioxide, and a similar 25% premium can be factored in for refining and other upstream emissions.  So 600 litres in your tank will mean two tonnes of emissions in the air.

Natural gas: the least dirty fossil fuel but a fossil fuel nonetheless, natural gas results in 49 KG of CO2 per gigajoule consumed; 25% added for drilling, transportation and leaked methane brings that to about 60 KG.  So an annual consumption of 60 gigajoules represents about four tonnes of emissions.

Electricity: in New Brunswick, 550 grams of carbon dioxide are produced for every kilowatt hour of electricity we use.  So if your average monthly bill is for 2000 kilowatt hours, that represents 12 tonnes of emissions per year.

Air travel: according to the International Civil Aviation Organization, a round trip from New Brunswick to Toronto produces a quarter-tonne of emissions.  Airplane emissions are a big part of the footprint of frequent flyers. 

Food: here things get more complicated, because the carbon footprint of our diet depends on many factors.  However, people who eat a lot of meat, buy a lot of imported food (especially perishable produce from far away) and lose a lot to spoilage and waste can be assured of a huge dietary carbon footprint.

Clothing, electronics, furniture, appliances, household goods, packaging, trash disposal, water and sewage – all consume energy and contribute emissions.  But it’s really, really hard to accurately calculate their detailed carbon footprint.  The one sure thing is that less is always better.

There are many carbon footprint calculators on the internet.  Most provide a useful snapshot and even some tips.  However, different calculators may generate very different carbon footprints for the same individual because they have been developed for other countries or climates, are based on incorrect assumptions or are too simplistic.

Yet if you try a few, you’ll undoubtedly notice three areas consistently emerging as the largest slices in your carbon pie chart.

First, personal travel: what you drive, how much you drive and how much you fly.

Second, home energy use: electricity, oil and gas.

Thirdly, diet.

The takeaway
Measuring one’s carbon footprint is a good thing; it provides helpful information and guidance.  If you’re up for it, great.  But if just the thought of it makes your eyes glaze over, know this simple bottom line: every action is a good action, but your greatest carbon footprint reductions lie waiting in your vehicle (and other travel), in your home (electricity and heating) and on your plate.