Carbon Footprint – About

What do we mean by carbon footprint?

Reduction in Greenhouse Gas Emissions (GGE) requires action by both government and individuals. It’s time for us all to get involved and take action. Getting to net-zero is a huge challenge and we need to move now. A key first step for individuals is to estimate their personal carbon footprints. Only by having a rough idea of what each of our contributions to GGE is can we select the changes which will lead to significant reductions that fit with our own particular circumstances.

The BBC Reality Check team has a good 3-minute video about carbon footprints which can be found here. The climate of our planet is changing because of an increase in greenhouse gases in the atmosphere caused by human activity. This is warming the planet causing many dangerous changes such as increasing rainfall, damaging storms, flooding, drought, wildfires, rising sea levels, crop failures and loss of species.

The most well-known greenhouse gas is carbon dioxide, but methane and nitrous oxide are also important. We can measure the amount of these in the atmosphere quite accurately and the measure commonly used is tonnes of carbon dioxide equivalent or CO2e. This quantifies the level of the greenhouse effect as if it was all carbon dioxide.

While we can accurately measure the CO2e in the atmosphere, estimating the contribution of each person is an inexact science. However, the good news is one only needs a rough idea to understand which are the key contributors. There are many tools available on the web to help estimate one’s carbon footprint. Their sophistication varies as they try to compromise between accuracy and asking the user for too much detailed information. They also vary in what they are seeking to measure, and this can lead to confusion. Different online calculators will give you different results, but the one we have selected fits in with government local and countrywide estimates.

Our measures are consumption-based. The calculations measure the CO2e each of us is responsible for, whether it is the gas we burn in our home boiler or what was used in the production of a TV we bought from Taiwan. Other calculators take no account of imports and exports, and yet others put the responsibility for calculating the figures for producing electricity on the power station rather than the individual. The factors that calculators use for each item also vary significantly. If you are interested, below are some of the specific differences between online calculators.

CO2 or CO2e

Carbon dioxide is the most important greenhouse gas and stays in the atmosphere for centuries. However, other gases are important too, such as methane and nitrous oxide. These have a bigger effect per tonne than CO2 but remain in the atmosphere for less time. The UN has come up with a measure that combines the effect, known as carbon dioxide equivalent.

TERRITORIAL v CONSUMPTION

The targets that countries have signed up to under the Paris accord are Territorial, in our case meaning the Greenhouse Gas Emissions (GGE) from activities on British soil. It does not take into account the emissions from goods manufactured abroad and imported. That way Britain reduced its GGE emissions enormously since 1980 by outsourcing much of its heavy industry. Using this measure the GGE per capita of the UK in 2017, according to DEFRA, was 6.5 tonnes. By contrast, ‘Consumption’, ‘Embedded’ or ‘Trade adjusted’ GGE takes account of a trade by adding imports and subtracting exports. Using this measure, DEFRA gives the GGE per capita of the UK as 12.0 tonnes. We feel this is a better measure for helping reduce the impact of each of us on the planet.

SCOPE

Carbon Footprint calculators vary in how many of the above per capita GGE components they seek to estimate for an individual. Usually, they include home electricity use and heating, transport and some elements of food. Coverage of the other things we buy is more variable, and most miss out on public sector providers such as the NHS and Education, which accounts for about 10% of the UK total.

INDIVIDUAL v HOUSEHOLD

Some elements are best worked out on a household basis, such as power usage, but others are more individual such as expenditure on clothes or commuting to work. Household estimates need to be divided amongst those benefiting and then added to the individual elements.

COUNTRY

The measures of GGE for different countries vary. So, for example, the GGE for a unit of electricity varies depending on how much is generated by renewable sources and how much by coal or gas power stations. Not all tools make this distinction, but we need one that uses UK measures.