Carbon Footprint Factsheet
A carbon footprint is the total greenhouse gas (GHG) emissions caused directly and indirectly by an individual, organization, event, or product.1 It is calculated by summing the emissions resulting from every stage of a product or service’s lifetime (material production, manufacturing, use, and end-of-life). Throughout a product’s lifetime, or lifecycle, GHGs such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), may be emitted. Differences in heat trapping are accounted for by the global warming potential (GWP) of each gas, resulting in a carbon footprint in units of mass of carbon dioxide equivalents (CO₂e) (See the Greenhouse Gases Factsheet). A typical U.S. household has a carbon footprint of 4 t CO₂e/yr,2 with 16-20% occurring in other countries such as China and Canada3. On a per capita basis, GHG emissions of an individual in the U.S. (14.4 t CO2e) is triple that of the global average (4.9 t CO2e).4
Sources of Emissions
Food (See U.S. Food System Factsheet)
- Food accounts for 10-30% of a household’s carbon footprint, often a higher percentage in lower-income households.6
- Production accounts for 68% of household food emissions, restaurant, retail, and wholesale trade combined accounts for 27%, and transportation accounts for 5%.7
- Food production emissions consist mainly of CO₂, N₂O, and CH₄, which result primarily from agricultural practices.8
- Meat products have larger carbon footprints per calorie than grain or vegetable products because of the inefficient conversion of plant to animal energy and due to CH4 released from manure management and enteric fermentation in ruminants.8
- Livestock emitted 192.6 Mt CO2e of methane in 2022 from enteric fermentation, 137 Mt (71%) of this from beef cattle.9
- In an average U.S. household, eliminating the transport of food for one year could save the GHG equivalent of driving 1,000 mi, while shifting to a vegetarian meal one day a week could save the equivalent of driving 1,160 mi.8
- A vegetarian diet greatly reduces an individual’s carbon footprint, but switching to less carbon intensive meats can have a major impact as well. For example, beef’s GHG emissions per kg (30.4 kg CO2e) are 7.2 times greater than those of chicken (4.2 kg CO2e).10
- Diets from the top 20% of income earners accounted for 7.9 times the GHG emissions as those from the bottom 20% of diets in the U.S.5
GHG Contribution by Food Type in Average Diet5
Household Energy (See Residential Buildings Factsheet)
- For each kWh generated in the U.S., an average of 0.83 lbs of CO2e is released at the power plant.11 Coal releases 2.25 lbs/kWh, petroleum releases 1.43 lbs/kWh, and NG releases 0.86 lbs/kWh. Nuclear, solar, wind, and hydroelectric release no CO2 when they produce electricity, but emissions are released from upstream production activities (e.g., solar cells, nuclear fuels, cement production).9
- Residential electricity use in 2022 resulted in 582.2 Mt CO2e, 9.2% of the U.S. total.9
- Space heating and cooling were estimated to account for 44% of energy used in U.S. residential buildings in 2023.12
- Refrigerators are one of the largest users of household appliance energy. In 2020, an average of 686 lbs CO2e per household was due to refrigeration.13, 14
- 26 Mt CO₂e are released in the U.S. each year from washing clothes.13, 14 Switching to a cold water wash once per week can reduce household GHG emissions by over 70 lbs annually.15
Personal Transportation (See Personal Transportation Factsheet)
- U.S. fuel economy (mpg) declined by 12% from 1988-2004, then improved by 35% from 2004-2022, reaching an average of 26 mpg in 2022.16
- Annual per capita miles driven were 9,937 in 2019, an increase of 9% since 1995.17 The average daily trip length for a U.S. commuter was 13.43 mi in 2022, a 17.2% increase since 2017.18
- Cars and light trucks emitted 1.03Gt CO2e or 16% of total U.S. GHG emissions in 2022.9
- Of the roughly 66,000 lbs CO2e emitted over the lifetime of an internal combustion engine car (assuming 93,000 miles driven), 84% come from the use phase.19 See the Electric Vehicle Factsheet for GHG emissions from ICEVs and EVs.
- Gasoline releases 19.4 lbs CO2 /gal when burned, compared to 22.5 lbs/gal for diesel.20 However, diesel has 11% more BTU per gallon, which improves its fuel economy.21
- The average passenger car emitted 0.74 lbs of CO2 per mile driven in 2022.16
- Automobile fuel economy can improve 7-14% by simply observing the speed limit. Every 5 mph increase in vehicle speed over 50 mph is equivalent to paying an extra $0.27-$0.54 per gallon.22
- Commercial aircraft GHG emissions, which vary by aircraft type, trip length, occupancy, and passenger and cargo weight, were 138 Mt CO2e in 2022.9 The average domestic commercial flight emitted 0.43 lbs of CO2e per passenger mile.9, 23
- Domestic air travel fuel efficiency (passenger miles/gallon) increased 112% from 1990-2022 largely due to increased occupancy.23 Emissions per domestic passenger-mile decreased 42.6% from 1990-2022, but the period of 2019-2021 saw a increase of 16% due to Covid restrictions.9, 23
- In 2022, rail transportation emitted 35.6 Mt CO2e, accounting for 2% of transportation emissions in the U.S.9
Solutions and Sustainable Actions
Ways to Reduce Your Carbon Footprint
- Reduce meat in your diet and avoid wasting food.
- Walk, bike, carpool, use transit, or drive a best-in-class vehicle.
- Ensure car tires are properly inflated. Fuel efficiency decreases by 0.2% for each 1 PSI decrease.24
- Smaller houses use less energy. Average energy use is highest in single-family houses (80.9M Btu), followed by mobile homes (61.3M Btu), apartments with 2-4 units (53.5M Btu), and apartments with 5+ units in the building (33.7M Btu).13 Whether you hand wash dishes or use a dishwasher, follow recommended practices to decrease water and energy use and reduce emissions.25
- Energy used by electronic devices in standby mode accounts for 5-10% of residential energy use, adding up to $100 per year for the average American household. Unplug devices or plug them into a power strip and turn the power strip off when not in use.26
- Choose energy-efficient lighting. Switching from incandescent to LED light bulbs saves an average household more than $200/year.27, 28
- Revamp the way you heat, cool, and power your home by making it energy efficient. Through 2032, homeowners can use federal tax credits to cut energy-efficiency upgrade costs by up to 30% or $3,200 annually, as well as receiving a 30% tax credit for clean energy equipment, such as rooftop solar, geothermal heat pumps, and energy storage.29
- Reduce and reuse to minimize personal waste. See the Municipal Solid Waste Factsheet.
- Think green before buying. Ask yourself: Do I really need it? Can I get it used? How long will it last? 30
- Reduce food waste by only buying what you need, composting food scraps, and donating unused food to food banks or shelters.31
- Purchase items with a comparatively low carbon footprint. Some manufacturers have begun assessing and publishing their products’ carbon footprints.
- Covering 80% of roof area on commercial buildings in the U.S. with solar reflective material would conserve energy and offset 125 Mt CO₂ over the structures’ lifetime32, equivalent to turning off 34 coal power plants for one year33.
- Replacing the roof and wall panels on the global fleet of shipping containers with aluminum would save $28 billion in fuel.34
U.S. Greenhouse Gas Emissions, 202135
Carbon Footprint Calculator
- Estimate your personal or household greenhouse gas emissions and explore the impact of different techniques to lower those emissions:
- U.S. Environmental Protection Agency: www3.epa.gov/carbon-footprint-calculator/
- The Nature Conservancy: www.nature.org/greenliving/carboncalculator/
- Global Footprint Network: https://www.footprintcalculator.org/
Center for Sustainable Systems, University of Michigan. 2024. "Carbon Footprint Factsheet." Pub. No. CSS09-05.
References
- The Carbon Trust (2018) Carbon Footprinting. https://www.carbontrust.com/resources/carbon-footprinting-guide
- Jones C., Kammen D. (2011) "Quantifying Carbon Footprint Reduction Opportunities for U.S. Households and Communities." https://pubs.acs.org/doi/pdf/10.1021/es102221h
- Song, K., et al. (2019). Scale, distribution and variations of global greenhouse gas emissions driven by US households. https://www.sciencedirect.com/science/article/pii/S0160412019315752?via%3Dihub#bb0095
- EDGAR (2023) GHG emissions of all world countries 2023. https://edgar.jrc.ec.europa.eu/report_2023?vis=co2pop#emissions_table
- Heller, M.C., et al. (2018). Greenhouse gas emissions and energy use associated with production of individual self-selected US diets. Environmental Research Letters, 13(4), 044004. https://iopscience.iop.org/article/10.1088/1748-9326/aab0ac
- Jones C., Kammen D. (2011) "Quantifying Carbon Footprint Reduction Opportunities for U.S. Households and Communities." https://pubs.acs.org/doi/pdf/10.1021/es102221h
- Boehm R., et al. (2018) "A Comprehensive Life Cycle Assessment of Greenhouse Gas Emissions from U.S. Household Food Choices." https://www.sciencedirect.com/science/article/pii/S0306919217310552
- Weber, C. and H. Matthews (2008) "Food miles and the Relative Climate Impacts of Food Choices in the United States." Environmental Science & Technology, 42(10): 3508-3513. http://pubs.acs.org/doi/pdf/10.1021/es702969f
- U.S. Environmental Protection Agency (EPA) (2024) Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990 - 2022. https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2022
- Heller, M., et al. (2020). Implications of Future US Diet Scenarios on Greenhouse Gas Emissions.. http://css.umich.edu/sites/default/files/publication/CSS20-01.pdf
- U.S. EPA (2024) “Emissions & Generation Resource Integrated Database (eGRID) 2022.” https://www.epa.gov/egrid/download-data
- U.S. EIA (2023) Annual Energy Outlook 2023. https://www.eia.gov/outlooks/aeo/tables_ref.php
- U.S. EIA (2023) Residential Energy Consumption Survey 2020. https://www.eia.gov/consumption/residential/data/2020/index.php?view=consumption
- U.S. EPA (2022) Emissions Factors for Greenhouse Gas Inventories. https://www.epa.gov/system/files/documents/2022-04/ghg_emission_factors_hub.pdf
- Mars C. (2016) Benefits of Using Cold Water for Everyday Laundry in the U.S. https://www.cleaninginstitute.org/sites/default/files/assets/1/Page/Cold-Water-Wash-Technical-Brief.pdf
- EPA (2024) The 2023 EPA Automotive Trends Report. https://www.epa.gov/automotive-trends
- U.S. Department of Energy (DOE), Oak Ridge National Lab (2022) Transportation Energy Data Book: Edition 40. https://tedb.ornl.gov/
- DOT, Federal Highway Administration (2022) Summary of Travel Trends. https://nhts.ornl.gov/assets/2022/pub/2022_NHTS_Summary_Travel_Trends.pdf
- Pero, F. et al. (2018) Life Cycle Assessment in the automotive sector: a comparative case study of Internal Combustion Engine and electric car. https://www.sciencedirect.com/science/article/pii/S2452321618301690
- U.S. EIA (2023) “Carbon Dioxide Emissions Coefficients.” https://www.eia.gov/environment/emissions/co2_vol_mass.php
- U.S. EIA (2024) Units and calculators explained. https://www.eia.gov/energyexplained/units-and-calculators/
- U.S. DOE, Office of Energy Efficiency and Renewable Energy (EERE) (2024) “Driving More Efficiently." https://www.energy.gov/energysaver/driving-more-efficiently
- U.S. Department of Transportation Bureau of Transportation Statistics (2023) National Transportation Statistics 2023. https://www.bts.gov/content/energy-intensity-certificated-air-carriers-all-services
- U.S. DOE, EERE (2016) "Gas Mileage Tips: Keeping Your Car In Shape." http://www.fueleconomy.gov/feg/maintain.shtml
- Porras, G. (2019) Life Cycle Comparison of Manual and Machine Dishwashing in Households. http://css.umich.edu/sites/default/files/publication/CSS19-15.pdf
- U.S. DOE (2012) “3 Easy Tips to Reduce Your Standby Power Loads.” http://energy.gov/energysaver/articles/3-easy-tips-reduce-your-standby-power-loads
- Liu, L., Keoleian, G. A., & Saitou, K. (2017). Replacement policy of residential lighting optimized for cost, energy, and greenhouse gas emissions. Environmental Research Letters, 12(11), 114034. https://iopscience.iop.org/article/10.1088/1748-9326/aa9447/pdf
- Department of Energy (2023) Energy Saving Hub. Energy Savings Hub | Department of Energy
- US Energy Star (2024) Federal Tax Credits for Energy Efficiency. https://www.energystar.gov/about/federal-tax-credits#homeowners
- US EPA(2024) Think Green Before You Shop. https://www.epa.gov/recycle/think-green-you-shop
- US EPA (2024) Reducing and Reusing Basics. https://www.epa.gov/recycle/reducing-and-reusing-basics
- Levinson, R. (2012) The Case for Cool Roofs. Lawrence Berkeley National Laboratory, Heat Island Group. http://heatisland.lbl.gov/publications
- U.S. EPA (2022) “Greenhouse Gas Equivalencies Calculator.” https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator
- Buchanan, C., et al (2018) “Lightweighting shipping containers: Life cycle impacts on multimodal freight transportation.” Transportation Research Part D 62:418-432. http://css.umich.edu/publication/lightweighting-shipping-containers-life-cycle-impacts-multimodal-freight-transportation
- UNCC (2023) United States. 2023 Common Reporting Format (CRF) Table. https://unfccc.int/documents/627772