Are you interested in reducing your personal carbon footprint? Have you wondered exactly how much recycling reduces global warming? In 2020 a meta-analysis paper was published by Diana Ivanova and coauthors that reviewed studies covering a range of personal consumption options. The researchers started with a dataset of 6990 studies from all over the world and used machine learning to winnow this down to the most relevant 53 studies. This meta analysis is great for two reasons: it gives a reliable average and it shows the uncertainty.
The data from this study is publicly available and I focused on two baskets, one with transportation choices and a second which includes common household actions like recycling. Let’s look first at transportation options. The amount of CO₂e saved is measured in tonnes per person per year -- living car-free saves 2.1 tonnes CO₂e per person per year (the average Canadian footprint is 15.2 tonnes CO₂e/person/year). Driving a battery operated vehicle (BEV) saves 2.0 tonnes CO₂e/person/year. In this global study “Shifting to a smaller car” generates a savings of 0.42 but I suspect this would be much greater in Canada where we drive the heaviest fleet in the world because we buy so many large pickups.
Actions cause “backfire” or “rebound” where a measure which is supposed to reduce carbon emissions actually increases them. You will notice this rebound effect in Figure 1 for “Shift to PHEV/HEV” (PHEV/HEV stands for plug-in hybrid electric vehicles and hybrid electric vehicles) and Figure 2 “Produce renewable energy.”
Some of the error bars are large. Should we be surprised at the size of error bars for BEVs or for installing renewable energy on your house? In both these cases the amount of carbon you can save depends on how clean your electricity mix is. Provinces with high-carbon electricity include Alberta, Saskatchewan and Nova Scotia. The Canadian Energy Regulator reports that these provinces make about 85% of their electricity from fossil fuels. A really dirty electricity mix reduces the advantage of driving a BEV, but gives solar panels on your home a large positive impact. The authors comment in the paper that the “electricity mix alone was found to explain almost 70% of the variability.” If you are interested in solar panels or buying a BEV you may be better off using an online calculator that factors in your local electricity mix.
People are often surprised that reducing or recycling stuff doesn’t reduce their carbon emissions by very much. Here “Less packaging”, “Fewer purchases”, “Less plastic”, “Recycle” and “Less paper” each have an impact of less than 0.2 tonnes CO₂e/person/year, approximately 1% of your total footprint. I do these things because they are sustainable (better for the planet) not because they reduce my overall carbon emission. I also expect that better recycling technology will also increase the carbon savings.
As a numbers geek I think this study is awesome. Having accurate numbers allows us to make meaningful choices. However, while people, especially in wealthy nations, need to reduce personal consumption, this spotlight shifts the focus from the political to the personal. Are your personal consumption choices powerful enough to solve global warming? No. The largest amount of carbon emission in Canada comes from the oil and gas industry (28% in 2021, according to the Government of Canada) which is heavily subsidized to the tune of 4.5-18 billion dollars a year. Choosing to go “car free” won’t make a dent in the state of the oil and gas industry. Other high-carbon subsidies support dairy, forestry and auto manufacturing.
The most powerful action I can take is to lobby the government (write, vote, protest) to make global warming and carbon reductions a priority. A close second is making the kind of lifestyle changes that significantly reduce carbon (for example my family is saving for a BEV). I reduce and recycle because it is the right thing to do but I acknowledge that it doesn’t have a large effect on my family's carbon footprint.
If you are interested in seeing the full range of measures and their carbon impact, a summary of the results was published in Science Alert “These 5 Charts Show What You Can Do Right Now to Fight Climate Change” by Max Callaghan. Thanks to Callaghan for pointing me in the direction of the data.
https://www.sciencealert.com/
You can read the full paper “Quantifying the potential for climate change mitigation of consumption options” at Environmental Research Letters.
https://iopscience.iop.org/
Articles and cartoons on Teaspoon Energy by Kristy Dyer are licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License You may reprint this as-is for free.
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