You’ve probably heard of the phrase “carbon footprint” — as in, "my company wants to lower its carbon footprint", or “taking that flight won’t be great for my carbon footprint”. But what does it actually mean?

It sounds rather abstract at first — “carbon” and “footprint” aren’t words that go together normally. But it helps to conjure an image of a footprint in the sand, evoking the simple idea that most things we do leave a trace.

According to the dictionary definition, the phrase evolved from the term “ecological footprint”, coined in the 1990s by the ecologist William Rees and regional planner Mathis Wacknergel, both working at the University of British Columbia in Canada.

They were referring to the total area of land and resources required to sustain an activity or population, including food production and water use. But carbon footprints are measured more simply than that. A phrase first used in 1999, it only refers to the weight, usually in tons, of carbon dioxide (CO2) emitted each year as a result of a particular activity.

It the following years, the term is thought to have been popularized by a 2004 advertising campaign launched by none other than the oil company British Petroleum (BP), which encouraged people to check their own carbon footprint and go on a "low carbon diet." The ad campaign has been criticized in the years since, given the fossil fuel extraction the oil giant itself is responsible for. 

Nowadays people often talk about their own personal carbon footprint, referring to their lifestyle, but it is used in relation to the impact that organizations or industries have too.

What is a carbon footprint exactly? 

According to the Nature Conservancy, a US environmental nonprofit, a carbon footprint is the total amount of greenhouse gases, either methane or CO2, generated by our activities.

Thinking in terms of a household, it relates to the carbon that is indirectly or directly emitted from the food you buy, the gas and electricity you use to heat your home, or the fuel needed for the car you drive.

The Carbon Trust, an organization that works with businesses to help them lower their carbon footprint, says that individual products can have a carbon footprint — relating to how they were produced, their distribution, and what happens to them when they are no longer in use. 

For example, can it be easily recycled, or will the product likely go to landfill sometime soon? In which case it will contribute to the emissions caused by trash breaking down in landfill. According to the University of Minnesota’s Institute on the Environment, trash released nearly 882 million tons of CO2 equivalent (meaning greenhouse gases including methane) in 2010.

The Carbon Trust certifies labels for some products that can help consumers figure out what carbon emissions are associated with what they buy. 

The average carbon footprint for a person in the United States is 16 tons per year, one of the highest in the world.

China, Canada, and Australia also have high per person carbon footprints. But it’s worth noting that this data refers to “per capita carbon emissions” (eg. the whole country’s carbon emissions divided by population size), rather than an exact measure of every single person’s own individual activities — but it helps give a rough idea.

The United Nations has said that in order to avoid a dangerous 2 degrees Celsius rise in global temperatures above pre-industrial levels, the average per capita carbon emissions need to be down to 2 tons per person each year by 2050 — a significant drop for some countries.

Lowering our own personal carbon footprint is a really important place to start to achieve this overall drop, but governments and industries will need to do their bit too.

How can you measure your carbon footprint?

There are a lot of carbon footprint calculators and apps out there which are free and easy to use and help give you some indication on how your lifestyle is contributing to carbon emissions.

Carbonfootprint.com offers calculators for both individuals and businesses and suggests handy ways to reduce your carbon footprint and improve it by, for example, planting trees. Or there’s a straightforward questionnaire created by the environmental nonprofit WWF (Worldwide Fund for Nature) that asks questions about your diet and travel habits, and offers advice. 

Another option is to download an app like Giki Zero, which helps by breaking down lifestyle changes into achievable steps, and even comes with a feature you can use to scan barcodes of products in shops to see their sustainability rating.

Or there's the aptly named Carbon Footprint and CO2 Tracker app, which can automatically track the carbon associated with your day to day travel. 

How can you lower your own carbon footprint?

Once you’re aware of it, there are lots of ways to lower your carbon footprint.

Of course, it would be very difficult to eradicate all the carbon emissions that occur in your day-to-day life — living in a heatless home and eating only the food grown in your garden would prove tricky to say the least. And it is the responsibility of everyone, including governments and businesses, to ensure we reach net zero. 

However, ensuring that your home is as energy efficient as possible is a good place to start. In the UK, for example, energy use in homes accounts for 14% of the country’s total carbon emissions.

Being aware of the food you eat also reaps rewards in terms of reducing your carbon footprint. A third of global greenhouse gas emissions comes from food production systems, according to the UN.

Reducing meat consumption is something the UN highly recommends. The methane gas output from cattle herding alone is massive and a report from the Intergovernmental Panel on Climate Change in 2019 found that even if renewable energy and electric vehicles become the norm, the environmental harm from food production alone will still cause dangerous climate change.

Another major area to look at is travel. Flying less and reducing the number of car trips you take are recommended as simple ways to reduce your carbon footprint, as well as investing in an energy efficient or electric car if you have to hit the road.

A fun a way to approach this challenge could be to gamify it, like the Swedish internet forums devoted to dealing with “flygskam”, or “flight shame”, do. The trend of feeling “flygskam”, and wanting to avoid it, has led people to challenge each other to get as far as they can without travelling by plane, often proving that it’s easier than you think.