United States of America's Historic Contribution to Global Warming Since 1850
Key Insights
Overall Warming Impact
The USA's impact from historic emissions is around 667,100 megatonnes of CO2‑equivalents, contributing about one‑sixth of the global total. On a population‑weighted basis, the per capita impact sits in the mid‑20s tonnes per capita per year-an Extremely High rating on the scale. This underscores a very large historic contribution to today's warming.
Fossil Fuels Drive The Story
Roughly two‑thirds of the USA's warming impact comes from fossil CO2. Emissions grew through the late 19th and early 20th centuries, surged during the post‑war era, and peaked in the early 2000s. Since then, coal CO2 has fallen steeply-dropping by roughly 80 megatonnes per year and down to about 700 by 2024-while oil CO2 has largely plateaued near the low‑2,000s since the mid‑1970s. Gas CO2 dipped in the 1970s-80s, then climbed steadily from the mid‑1980s to recent highs of around 1,700, highlighting a long‑running shift within fossil fuels.
Land And Methane Dynamics
Land‑use CO2 accounts for about one‑sixth of the impact, high in the late 19th/early 20th century (around 1,300) but trending down for most of the 20th century to the low hundreds and under 100 in recent years. Methane represents roughly an eighth: emissions rose to nearly 900 around the mid‑1970s, declined through the 2010s, then edged up again in the last decade. Within methane, emissions from energy‑related fugitive sources climbed over the long run, while livestock grew across the 20th century and then stabilized or eased slightly. Nitrous oxide rose sharply mid‑century and has been broadly stable to slightly lower since the 1970s; fluorinated gases are small but have trended upward since the late 1960s.
Leadership And Next Steps
Given the Extremely High per capita impact, the USA has a clear responsibility to lead. Rapidly cutting fossil CO2-accelerating coal phase‑down, reducing oil dependence, and limiting growth in gas-along with sustained reductions in methane and continued improvements in land‑sector outcomes, would deliver the largest benefits. Providing support to other nations to avoid similar high‑emission pathways can further amplify global progress.
Background
Historic Per Capita Emissions
Historic per capita emissions are a crucial long-period (since 1850), population-weighted (accounting for changing population size) indicator. It shows the contribution of greenhouse gas emissions of a nation per capita per year to the current warming.
The rating scale is:
- Extremely High: above 10 tonnes per capita per year
- Very High: above 7.5 tonnes
- High: above 5 tonnes
- Moderate: above 2.5 tonnes
- Low: above 0 tonnes
- Negative Emissions: under 0
Historically, we don't expect any nation to reach negative emissions. Current warming, or warming targets, like 1.5 °C and 1.7 °C are all based on the fact that there have been human-induced greenhouse gas emissions and there will be some more. It is clear, however, that some nations have had incredibly high historic contributions per capita.
Total Historic Impact
This is the total amount of CO2, CH4, N2O, and F-Gases emissions of a nation from 1850 till 2023 (last available year in the data) expressed in megatonnes of CO2-equivalents. The gases have different atmospheric lifetimes (decay) and warming effects, for this reason we use the GWP100 (100 year time horizon method) to calculate the global warming potential of N2O and F-Gases to express in CO2-equivalents. For CH4, which is a short-term gas, we use the GWP* method to express the historic impact in CO2-equivalents.
Wikipedia: Global Warming PotentialTotal Historic Share
This is a nation's total historic share of global emissions and its contribution to global warming. It is an indicator of historic responsibility. All nations share the responsibility to ensure that developing nations do not copy and repeat the behavior of nations with high historic greenhouse gas emissions, they should not buy into old unsustainable fossil-fuels-based technology, land-use, and infrastructure, rather foster a sustainable and cleaner development.
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. Population data are also from Global Carbon Project where available, however, for many nations it doesn't have historic population going back to 1850. Those historic gaps are filled with population data from Our World in Data.
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.
Our World in Data Population - Our World in Data
Update cycle: YearlyDelay: 7 monthsCredits: HYDE (2023); Gapminder (2022); UN WPP (2024) – with major processing by Our World in Data