How to build a carbon footprint

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Depending on which sources you look at, you might have noticed that the quoted figure for an average European carbon footprint varies quite a lot. This is likely because the different sources are measuring footprints differently. At Steps, we include in our carbon footprints:

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• All greenhouse gases (GHGs). This means that as well as carbon dioxide (CO2), we include in the calculation the other gases which warm our planet, such as methane (CH4) and nitrous oxide (N2O). In calculating a footprint, this is where “CO2e” comes from – the other greenhouse gases are illustrated as proxies of carbon dioxide based on their equivalent global warming potential (GWP).

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• Land use change. This refers to the net change in emissions caused by different usages of land. For example, a country or territory which has cleared lots of primary forest for agriculture would see a net increase in its overall emissions figure, since agricultural land is a less effective carbon sink than a healthy forest ecosystem.

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• Emissions transfers. This includes emissions for goods and services which are consumed in the territory, but are not produced there. For example, if you buy clothes or food in the UK which have been imported from another country, the emissions associated with the goods and services need to be included in the footprint as ‘consumption based’ emissions as well, since the emissions are generated as a result of buyers’ demand from the country.

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Steps’ carbon footprint calculator

 

Taking all these factors into account, our footprint calculator for the Climate Positive subscription plans merges the country carbon footprint with UN population data to generate average individual footprints for many countries and regions around the world.

To generate our calculator, we had to synthesise a few different datasets:

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• We retrieved emissions data from:

  • UNFCCC 

  • CAIT 

  • GCP 

• Emissions transfers data came from the GCP 

• Population data came from the United Nations 

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We took UNFCCC data as the primary data source; where emissions data for a country was missing within the UNFCCC dataset, we opted to revert to data provided by CAIT. The dataset from CAIT is more comprehensive than that from the UNFCCC, since it records measured emissions by particular authoritative institutions – many of them US governmental departments, like the EPA. This data could be subject to its own institutional or political biases – but our research and our calculations led us to consider it broadly accurate, and for non-Annex I countries it provides a much fuller dataset than that of the UNFCCC.

 

So, the emissions data we used for calculating Steps’ individual footprints was to use the most recent UN figure for national emissions (up to 2016) – unless it was missing, or greater than 6 years old. In either of these cases, we would revert to the most recent CAIT data for that country instead.

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Why doesn’t Steps calculate your footprint based on answering questions about your lifestyle?

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App footprint calculators which ask questions about your lifestyle to determine your emissions use what’s called a ‘bottom-up’ approach – where you insert data about your day-to-day life and build a footprint from the ground up.

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This approach can be considered fairly ‘accurate’ based on what you answer, but also tends to be ‘leaky’ as your footprint no doubt contains other areas that you weren’t able to disclose – which may be significant sources of emissions.

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When you look at an entire country’s emissions by the sum of all of its industries, the calculation doesn’t ‘leak’ because all known emissions are all present.

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Whilst your individual footprint may be higher or lower than the average for somebody who lives in your country, the law of averages provides us with a comprehensive initial figure for what your footprint would be, if all of the people in your country emitted the same.

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Reality check

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Whilst offsetting your carbon footprint with your Steps subscription is important, offsetting will not solve climate change on its own. If you live in a relatively wealthy country, the chances are that your carbon footprint is significantly higher than it needs to be, to help keep global warming below 1.5ºC or 2ºC.