What is a carbon footprint – and how do you measure yours?

As awareness of climate change grows, so does the desire to do something about it. But the magnitude of the problems it causes – from wildfires to melting glaciers to droughts – can seem utterly overwhelming. It can be difficult to make a connection between our everyday lives and the survival of polar bears, let alone how we as individuals can help change the situation.

One way to gain a quantifiable understanding of the impact of our actions, for better or for worse, is what is known as a carbon footprint. But while the concept is gaining traction — google “how do I reduce my carbon footprint?” yields nearly 27 million answers — it’s not always fully understood.

What is a carbon footprint?

So what exactly is a carbon footprint? According to Mike Berners-Lee, Professor at Lancaster University in the UK and author of The carbon footprint of everything, it is “the sum of all greenhouse gas emissions that had to take place in order for a product to be manufactured or an activity to be carried out”.

For most consumers in developed countries, these products and activities fall into four main categories: household energy use, transportation, groceries, and everything else, which is primarily the products we buy, from utensils to clothes to cars and televisions.

Each of these activities and products has its own footprint; A person’s carbon footprint is the combined sum of the products they buy and use, the activities they undertake, and so on. A person who regularly consumes beef has a larger food footprint than their vegan neighbor, but that neighbor’s overall footprint may be larger if they commute to and from work for an hour each day in an SUV while our meat eater drives the rides his bike to his office nearby. Their footprints may pale in comparison to the businesswoman opposite, who flies first class overland twice a month.

Not surprisingly, the size of a person’s carbon footprint generally increases with wealth. Berners-Lee writes in his book that the average world citizen has a carbon footprint equivalent to emitting seven tons of carbon dioxide per year. However, this figure is about 13 tons for the average Briton and about 21 tons per person in the United States.; It takes the “average American just a few days to match the annual footprint of the average Nigerian or Malian,” he writes.

How is a carbon footprint calculated?

It is not easy to calculate a carbon footprint; In fact, Berners-Lee calls it the “essential but impossible” measurement.

For example, consider the personal carbon cost of a commercial flight. On the one hand, the calculation is simple: Take how much fuel an airplane uses and how many greenhouse gases are emitted during a flight and divide this by the number of passengers. But the footprint is larger for first and business class passengers because they take up more space and because their higher cost creates an added incentive for the flight to actually go ahead. Other considerations include how much cargo the plane is carrying and the altitude at which the plane is flying.

Still, it’s a relatively easy calculation compared to evaluating the emissions involved in every step of, say, the manufacture of a car: the emissions produced at the assembly plant, the generation of electricity to run that plant, the transportation of all the components , the factories that produced the components, the manufacture of the machines used in those factories and the assembly plant, and so on, down to the extraction of the minerals that are the building blocks of the car.

Due to the complexity of such calculations, Berners-Lee concedes that in such cases “it is never possible to be entirely accurate”. The good news, he argues, is that for most people it doesn’t matter. “It’s usually enough to just have a rough idea,” he says.

What steps a person can take to reduce their personal footprint the most will, of course, depend on the type of lifestyle they are currently leading, and the same measures are not equally effective for everyone. For example, going electric in Vermont, where more than half of the state’s electricity comes from hydroelectric power, is far more impactful than in West Virginia, where it comes almost entirely from coal. Berners-Lee notes that “For some people, flying can represent 10 percent of their footprint, for some people it’s zero, and for some it’s such a large number that it should be the only thing on their mind.”

A cornucopia of calculators

To that end, a veritable cornucopia of personal carbon footprint calculators have popped up online in recent years. By inputting information about your household energy use, food consumption and travel habits, these calculators aim to give you an approximation of the amount of greenhouse gases emitted to support your lifestyle. This one from the Nature Conservancy focuses on home energy use, transportation, nutrition and shopping; this from the United States Environmental Protection Agency also accounts for transportation and energy use, but adds in waste — specifically how much you recycle. It also allows you to calculate how much your footprint could be reduced by taking actions like insulating your home, driving less, or getting a more fuel-efficient vehicle. This shows how much of an idealized personal carbon budget is consumed by eating two large cheeseburgers per month or two nights in a hotel.

Are carbon footprints just fossil fuel propaganda?

The earliest such calculator has been claimed to have appeared in 2004 as part of oil giant BP’s “Beyond Petroleum” campaign – a fact which has led some observers to criticize the push to reduce one’s personal carbon footprint as a “sham” to “Promoting the slant that climate change isn’t the fault of an oil giant, it’s the fault of individuals.”

“A few years ago, Shell posted a tweet in my thread asking, ‘What are you doing to reduce your carbon footprint?'” recalls Katharine Hayhoe, senior scientist at The Nature Conservancy and professor at the Texas Tech University. “So I responded something like this: ‘They are responsible for 2 percent of global emissions, which is the entire country of Canada; If you have a plan to get rid of these, I’d be happy to talk to you about my personal carbon footprint.” And they hid my answer.”

“It’s really important that we all think about what we consume, whether it’s fish, furniture or air conditioning: where it came from, what impact it has had,” says Kert Davies, director of the Climate Investigations Center. “But the industry then turned it around and did it: ‘It’s not our fault, you’re using our product. You deal with it.’”

That’s all the more egregious, he argues, given that the fossil fuel industry has been campaigning directly to restrict some of the measures often cited as ways for people to reduce their personal carbon footprint: more fuel-efficient vehicle standards or cleaner ones Energy technology for example.

“If it weren’t for the fossil fuel companies, you would already be driving an electric vehicle, your house would run more efficiently if the industry hadn’t blocked solutions and obscured the truth about the urgency of tackling climate change,” Davies adds.

Do carbon footprint calculators matter?

Hayhoe argues that there are other problems with the concept of personal carbon footprints, not least the fact that many of the proposed means of reducing these footprints are unavailable to those who, for example, do not have or cannot access public transport. Can’t afford the upfront cost of an electric car or heat pump, or live in food deserts where healthier, greener foods like vegetables and grains are harder to come by.

“The concept of personal carbon footprint plays a role in middle- to high-income people in high-income countries,” she explains. “The personal carbon footprint plays a very important role for the richest people in the world. But we have to recognize that it’s a limited concept – it doesn’t apply to everyone.”

Moreover, she argues, action is only a small part of what is needed to effect change in a system that, despite best individual efforts, continues to be dominated by fossil fuel production and use.

“I would say personal carbon footprint calculators are a useful tool for assessing the impact of your immediate actions: where you live, where you travel, what you eat,” she says. “But your climate shadow is much more important than your personal CO2 footprint. Where do you keep your money? How do you vote? What about the companies you work with, or the university you belong to, or the Rotary club you belong to—what do they do and how can you advocate for change?

“So in short, when people ask me what to do, I say do something, anything, but then talk about it. The only way to get everyone’s carbon footprint in the rich countries where it’s needed for a sustainable planet is to change the system, and to change the system we have to raise our voices.”

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