by Hannah Stewart –
Climate change is often regarded as the most pressing environmental issue of our time. Since climate change is driven by greenhouse gases such as carbon dioxide, we can quantify our individual contributions to climate change by measuring our “carbon footprint.”
Understanding our carbon footprint is critical to developing policies and behaviors that can reduce our impacts and mitigate some of the worst impacts of climate change.
This article will explain the relationship between climate change and carbon, the methods used to calculate carbon footprints, and ways that you can reduce your personal footprint.
What is the Relationship Between Climate Change, Greenhouse Gases, and Carbon Footprints?
The above graph from Berkeley Earth’s Global Temperature Report for 2019 not only shows that 2019 was the second warmest year on historical records since 1850 (with 2016 being the warmest year ever), it also demonstrates a dramatic increase in global temperatures since 1980.
Aside from record-breaking temperatures around the world, climate change is also responsible for more frequent droughts, wildfires, extreme weather phenomena such as hurricanes, rising sea levels, and shrinking glaciers.
These impacts of climate change are largely caused by the overwhelming quantity of greenhouse gases that humans have released into Earth’s atmosphere. These gases are a class of emissions that trap heat in Earth’s atmosphere and have been slowly warming the planet over the last several decades.
Carbon dioxide is the largest type of emission by volume in the world, making up about 65% of all emissions. In the United States, it comprised 80% of emissions in 2019.
A carbon footprint is the total amount of emissions that are generated by our everyday actions, measured in tons. These include the emissions that come from the production, use, and disposal of an object or service. Driving a car, using electricity, and eating certain foods are all “carbon heavy” activities that most people do every day.
In order to avoid the worst impacts of climate change, the world needs to keep global warming to under 2 degrees Celsius. In order to meet that goal, the average global carbon footprint will need to be about 2 tons per person by 2050. Currently, the average person in the U.S. has a 16-ton footprint. Around the world, the global average is closer to 4 tons.
This graph from the Global Footprint Network lists the countries with the largest footprints, their portion of the global footprint, and their portion of the world’s population. China and the U.S. have the two largest footprints, together contributing to more than a third of all global emissions. After the top 10 countries with the largest footprints, the rest of the world contributes to only 33.4% of global carbon emissions, despite being home to almost half of the world’s population.
Meeting that two-ton goal is going to require changing infrastructure, redesigning certain key industries, and large public awareness campaigns design to alter behaviors, especially in countries like the United States that have a large footprint disproportionate to their population.
Calculating Your Carbon Footprint
Before we can start implementing change, though, first we need to understand what factors into calculating a carbon footprint. The Carbon Trust defines a footprint as the emissions, “caused directly and indirectly by an individual, organization, event or product.” While this definition is simple, calculating a footprint is quite difficult.
An accurate carbon footprint must account for the emissions produced at every stage of the life cycle of a product or service. This includes: acquiring the raw materials, processing them into a usable form, transporting them to the demand source, using the item or service, and then the disposal of it.
A quick Google search can easily provide you with half a dozen online calculators from various organizations that can offer you rough estimates of your household’s average footprint. In order to create this estimate, these calculators will ask a series of questions about where you live, your energy bills, or your preferred modes of travel. Since each calculator was built by a different organization, the questions will vary slightly in topic and specificity, but they will generally cover these topics:
- Source of energy
- Energy consumption
- Travel patterns
- Diet
- Shopping habits
Source of Energy: Fossil Fuels vs. Renewable Energy
Energy is an integral part of our daily lives, particularly as a source of heat or for electricity, and there are several different ways to produce it. The mode of production plays an important role in determining the carbon footprint of energy.
Fossil fuels, such as coal, oil, and natural gas, have been popular sources of energy since the industrial revolution. They are all fairly easy to transport and dense with stored carbon that can become large amounts of power. However, burning fossil fuels to get energy also releases the carbon emissions that are causing climate change. For every kilowatt/hour of energy produced, coal will release 2.2 pounds of carbon dioxide emissions, petroleum will release 1.9 pounds, and natural gas will emit 0.9 pounds.
Renewable energy, on the other hand, is nearly the opposite of fossil fuels. Solar panels, wind farms, and hydropower dams are location-dependent, which means that they require a certain climate or environment to be effective. However, at the point of electrical production, clean energy releases no carbon emissions.
As a brief side note, it’s important to point out that renewables do not have a carbon footprint of zero. Building solar panels or wind turbines usually requires the use of construction vehicles or factories that run off of fossil fuels, which will release greenhouse gas emissions. As a result, if we look at the entire product life cycle, the carbon footprint is small, but it is not zero.
As a result of the different footprint sizes of fossil fuels vs. renewables, the source of your energy will have an impact on your carbon footprint. For example, if you have solar panels on the roof of your house, your electricity will have a smaller carbon footprint because it comes from a clean energy source. However, if you heat your home with gas, your carbon footprint will be larger.
Energy Consumption: Energy Efficiency vs. Waste
In addition to the source of your energy, the size of your carbon footprint also depends upon how much total power you use. This includes heating and cooling systems, kitchen appliances, lights, and all other electronic devices such as phones and computers. Regardless of the source of energy, using more power will result in a larger carbon footprint.
The size of a home will also impact its consumption. For example, an apartment with good insulation will use a smaller amount of energy in order to reach a comfortable temperature than a sprawling, multi-storied house.
There are several ways for homes to waste power and unnecessarily increase their carbon footprint, but one of the most common kinds is known as “energy vampires.” A vampire is any device that continues to use electricity, even if it’s turned off. Cable boxes, video game consoles, or a home assistant (such as a Google Home or an Amazon Dot) all fall into this category. Similarly, phone or laptop chargers that are left plugged into an outlet will continue to conduct power, even if they’re not plugged into anything. Energy vampires may account for as much as 20% of your monthly power bill.
Travel Patterns: The Way You Move Matters
The transportation sector is responsible for 29% of all greenhouse gas emissions in the United States and about 21% of carbon dioxide emissions globally. However, not all modes of transportation have the same carbon footprint.
A study conducted by the UK government found that domestic flights for distances of less than 1,000 kilometers had the largest carbon footprint out of any mode of transportation. Airplanes burn massive amounts of fuel to transport relatively few passengers at a time. The study reported that planes burn 255 grams of carbon dioxide (CO2) equivalents per passenger kilometer (“CO2 equivalents” is a unit of measure that quantifies the global warming potential of multiple greenhouse gases relative to CO2). For comparison, traveling via bus produces only 105 grams of CO2 equivalents per passenger kilometer. Using a bike for short distances produces even fewer emissions: only 16 to 50 grams of CO2 equivalents.
Ultimately, the study found, the carbon footprint of any mode of transportation will be determined by three factors: the length of the trip, the source of energy, and the number of passengers.
The length of the trip matters in this study because the researchers divided total emissions by distance. Traveling farther, i.e. dividing by a larger denominator, will reduce the CO2 emissions released per unit of distance and therefore reduce the relative carbon footprint. Additionally, some modes of travel are not appropriate for certain distances. For example, while you could argue against flying from New York City to Boston because there are other, less carbon-intensive options available for such a comparatively small distance, the only practical way to move people or goods across entire oceans is to fly.
As mentioned in an earlier section, source of energy also has an impact on carbon footprints. In the case of transportation, whether a vehicle runs on electricity or diesel impacts its emissions. The aforementioned UK study found that, while a medium-sized petrol car that runs on petrol releases 192 grams of CO2 equivalents per passenger kilometer, the same sized electric car releases only 53 grams of CO2 equivalents per passenger kilometer. Of course, electricity produced by solar panels would have a different carbon footprint than if it were produced by natural gas.
Finally, similar to the impact of distance, the number of passengers in each vehicle will affect the carbon footprint. Because the UK study measured emissions in units of CO2 equivalents per passenger kilometer, having a larger number of passengers will also reduce the relative carbon footprint. For example, the diesel car that emitted 192 grams of CO2 equivalents was modeled assuming that it held only the driver. Add one passenger to that scenario and suddenly the CO2 equivalents are cut in half to only 96 grams.
Food: Plant-Based Diets vs. Meat-Based Diets
Food accounts for 10%-30% of a household’s carbon footprint and can be higher in lower-income homes. Approximately 68% of food emissions come from production and 5% come from transportation. Within the general umbrella of “food emissions” though, there is variation amongst the different food groups.
Meat products, such as pork, chicken, and beef, have larger carbon footprints than fruit or grains. Part of this is because of the inefficient transfer of energy between different parts of the food chain. A plant, such as a fruit or vegetable, can get almost everything it needs to survive from the sun; it doesn’t need anything else. Herbivores, like cows, aren’t nearly as efficient. It takes a lot of energy for an herbivore to digest plants and convert them into a form that an animal can use. This results in a small “profit” of energy compared to what was originally stored in the plant. This loss only gets worse as you travel further up the food chain to omnivores such as humans.
Another contributing factor to meat’s larger carbon footprint is the bodily emissions of ruminants, such as cattle, sheep, and goats. Digesting grass and other raw plant matter produces methane gas, which is a greenhouse gas 25 times more potent than CO2. In the U.S. alone, ruminants released 178 million tons of CO2 equivalents into the atmosphere in just 2018.
Different types of meat also have different carbon footprints. Beef and lamb production has a much higher carbon footprint than chicken or pork. This is believed to be due to the food requirements of lamb and beef and the land use changes necessary to accommodate them.
Food waste also has an impact on carbon footprints. From field to landfill, there is a percent of waste at every step in the life cycle of food. For example, one-third of all the food produced in the world never actually reaches the tables of consumers. It is either left unharvested in the field to rot or it is discarded as too “ugly” to sell to consumers. According to the Food and Agriculture Organization of the United Nations, if food waste was a country, “it would be the third largest emitting country in the world.” Any time food is lost to landfills, it runs the risk of decomposing into dangerous methane, further exacerbating the impacts of climate change.
Shopping Habits: Fast Fashion and Waste
Two of the worst shopping behaviors in terms of carbon footprints are “fast fashion” and single-use items.
The first is the fairly new trend in fashion that prioritizes short-lived fads and low prices over quality or environmental impact. Under this system, clothes should be bought frequently, discarded easily, and made as cheaply as possible. While these prices may be beneficial for budgets, the clothes will rip, fray, and fade quickly. One study suggests that the average garment-use time before disposal is now 36% shorter than it used to be. The low prices encourage buyers to simply throw away ruined clothing instead of attempting to repair it. Since 60% of the trashed fabric is made of fossil fuel-based synthetics, many of those cheaply-made clothes may sit in landfills for centuries because they will never decompose.
Single-use items, notably single-use plastic, are similarly cheap, convenient, and easily disposable. From plastic water bottles and cutlery to packaging, single-use items were made to be thrown away. They require no maintenance or thought beyond your immediate need for them.
Problematically, though, plastic is also made from fossil fuels, which means that once they’re thrown away, they won’t decompose for centuries. Additionally, when exposed to sunlight for a long time, plastic will release methane and ethylene, both of which are powerful gases that contribute to climate change. In terms of CO2, the production and disposal of plastic in Europe adds about 400 tons of emissions to the atmosphere every year.
How to Reduce Carbon Footprint
Now that we’ve explored the link between carbon and climate change and examined the biggest contributing factors to a carbon footprint, it’s time to look at ways to reduce your carbon footprint. Broadly speaking, there are two ways to improve your environmental impact: 1) support the restoration of the environment and 2) incorporate new behaviors into your everyday life.
Environmental Restoration
Earth already has some biomes and habitats that excel at pulling CO2 out of the atmosphere before it can do any damage. However, pollution, deforestation, and degradation have all taken a heavy toll on the environment and severely impaired its ability to mitigate climate change. Helping to restore the environment will help increase Earth’s capacity to safely hold CO2.
Forests and tropical rainforests are carbon sinks, a type of environment that can store large amounts of carbon in the form of organic material. Slash-and-burn agriculture and deforestation have released the stored carbon and are responsible for 12% of global emissions. Supporting policies that protect carbon sinks and making financial contributions to restoration projects could potentially pull 3.1 gigatons of CO2 out of the atmosphere and back into forests.
Carbon offsets are a controversial way to help fund restoration projects. Offsets are certificates that promise a reduction in emissions, usually by someone other than the buyer in some other location. Proceeds from offset sales go towards funding the project, but critics claim that offsets are just a way for wealthy nations to pass the burden of responsibility off onto lower-income nations.
Build Better Behaviors
For a more hands-on and direct way of reducing your carbon footprint, consider adopting new behaviors based on the five carbon footprint factors described above.
To reduce the carbon footprint of your energy source, consider switching the fuel source for your home from fossil fuel to a renewable source, such as eco-friendly solar panels that you can install on your roof. This kind of switch is more tricky for anyone living in an apartment or who doesn’t have the space for solar panels. Consider looking into whether your electric utility company offers any “green” options. Many electric utility companies are already investing in large solar farms or offshore wind turbines and may offer options that include generating a percent of your electricity from clean energy.
Energy use is a much more approachable way to make a difference in your carbon footprint, regardless of the size and shape of your home. For example, energy-efficient appliances, such as washing machines, refrigerators, and dishwashers, use less energy to perform the same tasks as your normal appliances, thereby reducing your monthly bills and your carbon emissions. Similarly, replacing the light bulbs in your home with LED light bulbs, taking shorter showers, and using less hot water (especially in your washing machine) whenever possible will reduce your energy demand.
If you are able, walk or cycle around your neighborhood in order to complete your errands, instead of taking your car everywhere. Using a bike has one of the lowest carbon emissions rates out of any vehicle and can double as exercise. If your home has a robust public transportation system, drive less as you go about your day and save on fuel. Some areas weren’t designed with walking or cycling in mind though. If those options aren’t safe, set up a carpool with your neighbors. Organize trips to school, work, or the grocery store together and reduce the number of cars on the road.
Some list articles that offer tips on reducing your carbon footprint may advise you to buy locally grown produce. While supporting small businesses and nearby farms is excellent for the local economy, it will have a fairly small impact on your carbon footprint. Transportation accounts for only 5% of the emissions incurred by food, while 68% comes from production. Eating less meat every week, or even just switching out carbon-intensive beef for chicken, will have a bigger impact.
Finally, the next time you go shopping, consider the life span of what you’re buying and how you plan on disposing of it. For clothing, consider shopping at a thrift or consignment store. The clothes there will likely be marked down from their normal retail price and if they’ve been worn before, you already know that they can last. Avoid single-use plastic every chance you get: Instead of buying a plastic water bottle every time you feel thirsty, carry around a dishwasher-safe reusable bottle; Invest in beeswax food wrap instead of plastic sandwich bags or cling wrap; use canvas bags to carry your groceries instead of plastic bags.
Conclusion
It’s up to you to decide how far you want to reduce your personal carbon footprint. This calculator, designed by the U.S. Environmental Protection Agency, will calculate your current and future carbon footprint by asking questions that cover several of the topics discussed here. When I completed the quiz (which takes less than 5 minutes), the final report told me that my personal carbon footprint was almost 17,000 pounds and that, over five years, I could avoid more than 400,000 pounds of CO2.
The urgency of climate change demands that we all find ways to reduce our personal footprints. Together, billions of small choices can add up to mitigating the planetary weather changes, preventing environmental degradation, and building a healthier planet.
If you are interested in more, check out our guide on how to become more eco-friendly.
Q&A
Why are carbon footprints important?
Carbon footprints are one way to quantify the impact of each person, company, or nation on climate change. Understanding your carbon footprint helps to identify ways that you can modify your lifestyle or behavior in order to mitigate and avoid the worst impacts of climate change.
Who invented the carbon footprint?
In 2005, the fossil fuel company BP coined the term “carbon footprint” as part of a marketing campaign designed to convince consumers that the burden of solving climate change was the responsibility of individual people. It is believed that the goal of this campaign was to shift attention and blame away from BP’s oil-drilling practices.
What is the average carbon footprint?
The size of the average carbon footprint varies significantly based on location. China and the United States have the largest average footprints, despite having less than 25% of the world population. In the United States, the average carbon footprint is about 16 tons of CO2.
