From cooking dinner to jetting away for vacation, the choices you make in your day‑to‑day life leave a mark on the environment.
A carbon footprint is a way to measure how much climate‑warming pollution those choices generate. In simple terms, it’s the mark our everyday activities leave on the climate.
The “size” of your carbon footprint depends on multiple factors. The primary one is the amount of heat‑trapping pollution (called greenhouse gases) released into the atmosphere by a given activity.
People, products and entire industries have carbon footprints. Your personal footprint includes emissions from a variety of sources: your daily commute, the food you eat, the clothes you buy, everything you throw away, and more. The larger your footprint, the heavier the strain on the climate.
To halt climate breakdown and avoid its worst impacts, we need to do two things: 1) shift to a low‑carbon economy and 2) protect our best natural allies in the fight against climate change. Who are our natural allies? Forests, soils, grasslands, mangroves and tidal marshes, which store large quantities of carbon that would otherwise heat the atmosphere.
Drastically cutting greenhouse gas emissions will require everyone at every level — from individuals and businesses to entire countries — to reduce their respective carbon footprints. Here’s the information and practical steps you’ll need to get started.
How is a carbon footprint measured?
A carbon footprint estimates the total amount of greenhouse gases — the heat‑trapping gases in our atmosphere that trap and release heat and contribute to climate change.
While the measurement actually accounts for the release of a number of different world‑warming gases — like methane, nitrous oxide and fluorinated gases — results are typically expressed in terms of “carbon dioxide equivalency,” or CO₂‑equivalent (for example: 5 tons of CO₂‑equivalent).
This common unit enables scientists and policymakers to convert different gases into a single measure — much like converting different currencies into U.S. dollars — making it easier to compare the climate impacts of different activities, events or even entire industries.
Definitions
Life-cycle assessment
While a carbon footprint focuses on greenhouse gas emissions, a life‑cycle assessment looks at a wider range of environmental effects. It helps answer a simple question: What is the total environmental impact of a product or service over its entire lifetime?
Think of a life‑cycle assessment as a full lifetime measure of all of the energy and materials used to develop, use and dispose of a product or service.
Take a car, for example. A comprehensive life‑cycle assessment would take into account all phases of the vehicle’s life, including the sourcing and processing of raw materials used in production, assembly at the manufacturing facility, transfer to the showroom and the eventual scrapping of the vehicle when its days are done. And that’s before factoring in the impact of regular maintenance and the fossil fuels burned while driving the car over the course of its life.
How does carbon affect climate change?
Greenhouse gases trap heat emitted by both the sun and the Earth's surface. As humans cut down forests or plow over grasslands, the carbon held in those ecosystems is released into the atmosphere. Add that to all the fossil fuels that our species burns, and that adds up.
High concentrations of these greenhouse gases, especially carbon dioxide, are raising the average surface temperature of the planet to levels that cause a whole host of life‑threatening impacts. Atmospheric carbon dioxide levels have risen more than 40 percent since the middle of the 18th century, and climatologists estimate that current levels are as high as they've been in some 14 million years.
As carbon dioxide levels continue to climb, fueling further temperature increases, the cumulative effects — including increased ocean acidification, rising sea levels, more frequent and intense storms, mass species extinctions, food scarcity and greater economic inequality — will be felt worldwide.
United States' per capita carbon footprint is14.2 metric tons
By the numbers
Around the world, the average person generates about 4.7 metric tons (MT) of carbon dioxide emissions each year. In the United States, it's more than three times that number — 14.2 metric tons.
Carbon footprints vary widely from country to country, largely because of differences in energy systems, transportation, infrastructure and consumption patterns. Even so, the U.S.’s per‑capita carbon footprint — meaning emissions per person, on average — is larger than that of most nations, including Canada (13.4 MT), Russia (12.2 MT), Germany (6.77 MT), Japan (7.77 MT), China (8.66 MT), the UK (4.53 MT), France (3.97 MT), Brazil (2.28 MT) and India (2.2 MT).
Your carbon footprint
So if the average person worldwide is responsible for emitting the equivalent of nearly five metric tons of carbon dioxide per year, where does it all come from? The truth is, dozens of daily actions — along with long‑term lifestyle choices — shape each of our carbon footprints. Here are five of the most significant contributors.
Family size
Family size plays one of the largest roles in an individual’s long‑term carbon footprint, with each child adding an average of 58 metric tons of CO₂‑equivalent per year to a household’s total in a developed country.
Transportation
Cars and planes are the main contributors here. Owning and regularly driving a car adds an average of 4.6 metric tons of CO₂‑equivalent to your yearly footprint, while a single transatlantic flight adds about 1.6 tons.
Heating and air conditioning
In the United States, regularly heating and cooling your home adds roughly 7.5 metric tons of CO₂‑equivalent to your annual footprint. That’s because most American homes are still powered by fossil fuels such as coal and gas, rather than renewable sources like solar and wind.
Here’s how different energy sources compare: A typical coal power plant produces about 1 kilogram (that’s 1,000 grams) of CO₂ per kilowatt‑hour of electricity. By comparison, natural gas produces about 435 grams of CO₂ per kilowatt‑hour; solar power produces about 41 grams; and wind produces just 11 grams.
Food
For the average person, eating meat adds about more than 2 metric tons to your annual carbon footprint. This has less to do with emissions produced directly by animals and more to do with the energy required to grow, harvest and transport the crops that feed livestock.
Not all meats are created equal. Beef requires far more feed, water and land than chicken and has a carbon footprint up to 10 times more than chicken.
Laundry
Washing and drying clothes in a machine adds up to about 159 kilograms (350 pounds) of CO₂‑equivalent per household over the course of a year — about half from heating water during washing and the other half from drying.
Related resources
Calculate your carbon footprint
Carbon emissions from your daily choices, from transportation to diet, can make an impact. We are at a critical climate tipping point — and you can be a part of the solution.