United States of America's Yearly Greenhouse Gas Emissions in CO₂ Equivalent
Key Insights
Fossil CO2 Dominates History
The USA's long-term climate impact is driven primarily by CO2 from fossil fuels-roughly two-thirds of the historic total. Emissions climbed steadily from the late 19th century, surged through the post‑war era, and peaked in the mid‑2000s at over 6,000 megatonnes. Since then they have fallen, reaching around 4,900 today. This decline marks a significant shift after more than a century of rapid growth.
Shifting Fossil Fuel Mix
Within fossil CO2, the mix has changed markedly. Coal rose for decades then fell sharply since the late 2000s-from well over 2,000 to around 700 megatonnes. Oil grew rapidly after World War II and has been broadly stable since the late 1970s, hovering near 2,200. Gas has trended upward since the mid‑1980s, reaching nearly 1,800, offsetting part of the coal decline.
Land Use And Methane Transitions
CO2 from land use was a major source in the late 1800s and early 1900s, around 1,300 megatonnes, but has steadily declined to roughly 100 today. Methane rose to nearly 900 by the mid‑1970s, then emissions eased through the mid‑2010s; during this period the warming impact from methane declined. Since 2015, emissions have increased again toward nearly 800, lifting its contribution. Nitrous oxide climbed to roughly 250 by the early 1970s and has edged down since. Fluorinated gases rose from near zero to around 250 but remain a small share.
Actionable Outlook For The USA
Today, overall fossil CO2 is falling, led by rapid coal declines, while oil is largely flat and gas is still rising. Methane has turned upward again. Sustained progress hinges on maintaining coal's downturn, reversing growth in gas, and bending oil lower, while keeping land‑use emissions on a path toward further reduction.
Background
Greenhouse gas emissions from human activities are the main drivers of human-induced warming. In the scientific literature, human-induced emissions are often referred to as anthropogenic emissions.
- CO2 Fossil Fuels and Industry (CO2 FFI)
- CO2 Land-Use, Land-Use Change and Forestry (CO2 LULUCF)
- Methane (CH4)
- Nitrous oxide (N2O)
- Fluorinated gases (F-gases)
Emissions from all different gases are expressed in CO2-equivalent units to make it possible to compare the relative emissions from these different gases. CO2-equivalents are calculated using the global warming potentials of the respective gases, in this case using a 100-year time horizon.
Wikipedia: Global Warming PotentialTotal Historic Share
Emissions from all different gases are expressed in CO2-equivalent units to make it possible to compare the relative emissions from these different gases. CO2-equivalents are calculated using the global warming potentials of the respective gases, in this case using a 100-year time horizon.
CO2 From Fossil Fuels and Industry
The sources are mostly fossil-fuel combustion emissions from coal, oil, and gas, as well as emissions from industrial processes such as cement production. Cement also absorbs CO2 out of the atmosphere through carbonation, which reduces emissions by about 0.8 Gt per year and is included here.
CO2 From Land-Use, Land-Use Change, and Forestry
The main driver of these emissions is deforestation, which includes logging and forest degradation, as well as other land-use change activities. The emissions also take into account the absorption of CO2 by processes that remove CO2 from the atmosphere, such as afforestation and reforestation. It is the net effect that is indicated here.
Methane (CH4)
Methane emissions are caused by human activities such as rearing livestock, agricultural practices, and fugitive fossil fuel emissions.
Nitrous Oxide (N2O)
Common sources of these emissions are fossil fuel emissions and the agricultural use of synthetic fertilizer and manure.
Fluorinated Gases (F-gases)
Fluorinated gases are a group of gases defined by UNFCCC: hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3). Fluorinated gases are also known as halogenated gases.
Wikipedia: Greenhouse Gas EmissionsIPCC: Annual Report 6, 5.2.1 5.2 Historical Trends, Variability and Budgets of CO2, CH4 and N2O
Units and Measures
CO2-equivalent emissions are expressed in the total weight in megatonnes per year. 1 Megatonne is equal to 1 million tonnes.
Wikipedia: MegatonneWikipedia: Global warming potential
About the Data
The last available year in all the emission datasets is 2023. CO2 emissions data is from the Global Carbon Project. It contains national CO2 emissions from fossil sources and land-use change. Emissions from CH4, N2O and F-gases come from the PRIMAP-Hist dataset. It is a rich dataset that combines several published sources to create a historical emissions time series for various greenhouse gases.
The Key Insights paragraph was created using a large language model (LLM) in combination with our data, historic events, and a structured approach for best accuracy by separating the context generation from the interpretation and narrative.
Data Sources
Global Carbon Budget 2024 Global Carbon Budget
Update cycle: yearlyDelay: ~ 10 months after the end of the year. Current year values are estimated and published in November.Credits: Friedlingstein et al., 2024, ESSD. Friedlingstein, P., O'Sullivan, M., Jones, M. W., Andrew, R. M., Hauck, J., Landschützer, P., Le Quéré, C., Li, H., Luijkx, I. T., Olsen, A., Peters, G. P., Peters, W., Pongratz, J., Schwingshackl, C., Sitch, S., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S. R., Arneth, A., Arora, V., Bates, N. R., Becker, M., Bellouin, N., Berghoff, C. F., Bittig, H. C., Bopp, L., Cadule, P., Campbell, K., Chamberlain, M. A., Chandra, N., Chevallier, F., Chini, L. P., Colligan, T., Decayeux, J., Djeutchouang, L., Dou, X., Duran Rojas, C., Enyo, K., Evans, W., Fay, A., Feely, R. A., Ford, D. J., Foster, A., Gasser, T., Gehlen, M., Gkritzalis, T., Grassi, G., Gregor, L., Gruber, N., Gürses, Ö., Harris, I., Hefner, M., Heinke, J., Hurtt, G. C., Iida, Y., Ilyina, T., Jacobson, A. R., Jain, A., Jarníková, T., Jersild, A., Jiang, F., Jin, Z., Kato, E., Keeling, R. F., Klein Goldewijk, K., Knauer, J., Korsbakken, J. I., Lauvset, S. K., Lefèvre, N., Liu, Z., Liu, J., Ma, L., Maksyutov, S., Marland, G., Mayot, N., McGuire, P., Metzl, N., Monacci, N. M., Morgan, E. J., Nakaoka, S.-I., Neill, C., Niwa, Y., Nützel, T., Olivier, L., Ono, T., Palmer, P. I., Pierrot, D., Qin, Z., Resplandy, L., Roobaert, A., Rosan, T. M., Rödenbeck, C., Schwinger, J., Smallman, T. L., Smith, S., Sospedra-Alfonso, R., Steinhoff, T., Sun, Q., Sutton, A. J., Séférian, R., Takao, S., Tatebe, H., Tian, H., Tilbrook, B., Torres, O., Tourigny, E., Tsujino, H., Tubiello, F., van der Werf, G., Wanninkhof, R., Wang, X., Yang, D., Yang, X., Yu, Z., Yuan, W., Yue, X., Zaehle, S., Zeng, N., and Zeng, J.: Global Carbon Budget 2024, Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2024-519, in review, 2024.
PRIMAP-hist The PRIMAP-hist national historical emissions time series (1750-2023)
Update cycle: Every few monthsDelay: Less than 1 yearCredits: Gütschow, Johannes; Busch, Daniel; Pflüger, Mika (2024): The PRIMAP-hist national historical emissions time series (1750-2023) v2.6. Zenodo.