Breakdown of Yearly Human-Induced Gross CO2 Emissions

What is the Breakdown of Yearly Human-Induced Gross CO2 Emissions?

This is a breakdown by source of the yearly CO2 emissions from human activities and processes expressed in gigatonnes. It is critical to know and track the sources of human CO2 emissions in order to understand their individual impacts on climate change.

The sources of human CO2 emissions are

  • Coal combustion
  • Oil combustion
  • Gas combustion
  • Other fossil processes
  • Land-use change

Coal, oil and gas combustion

Fossil fuel CO2 emissions from the combustion of coal, oil and gas are emitted by processes in electricity generation, transport, industry, and the building sector. All processes can be linked to human activities. Examples include driving cars with combustion engines burning diesel or gas, or electric cars charged by electricity from a power plant that burns coal.

Other fossil processes

Fossil CO2 emissions from other processes include sources like cement manufacturing and production of chemicals and fertilizers. Cement also has an absorption factor highlighted in the absorption breakdown chart.

Land-use change

Human civilization emits CO2 by changing and managing its land. Those emissions come, for example, from deforestation, logging, forest degradation, harvest activities and shifting agriculture cultivation. Land-use change also absorbs considerable amounts of CO2, which is shown in the absorption breakdown chart. Land-use change emits more than it absorbs, so the net effect is still emissions, but less than for coal, oil and gas.

Yearly Absorption of Human-Induced Gross CO2 Emissions
Wikipedia: Greenhouse Gas Emissions
Earth System Science Data: GCP 2020 paper: Section 2.2 Land-use change; Section 2.1 Fossil fuel emissions
IPCC: Annual Report 6, Anthropogenic CO2 emissions

Units and measures

CO2 emissions are expressed in the total weight in gigatonnes.

Wikipedia: Gigatonne

Insights from this chart

Until the early 1900s, coal was the foremost fossil fuel, contributing to a steady rise in CO2 emissions. From 1910 to 1950, the use of coal didn’t really increase, with declines during the two world wars and the Great Depression. After 1950, coal use grew steadily once more until the 2000-2011 period, when the rapid development of China caused a major increase in CO2 emissions from coal combustion. The USA and Europe started reducing coal combustion around 2008. In the last ten years there has been no overall increase in coal use, but CO2 emissions from coal combustion are still very high.

After the Second World War came a quick growth in oil use that ended with the Arab oil embargo (1973) and the Iranian revolution (1979). Since then, the use of oil – and CO2 emissions from oil combustion – have grown steadily and are still very high.

Emissions from gas combustion have always been lower than those of coal and oil. They have been growing steadily since the 1960s and are still growing fast. Worldwide gas combustion produces almost the same amount of energy as oil and coal, but it emits less CO2, which is why many countries focus on first reducing coal and oil by switching to gas. Despite the lower emissions compared to other fossil fuels, gas combustion is still a major driver of climate change.

Land-use change emissions are high and relatively steady. This chart shows the gross CO2 emissions due to anthropogenic land-use. Land-use change also absorbs significant amounts of CO2 from the atmosphere. The net effect is around 3 gigatonnes and is in a reducing trend. The significant peak of land CO2 emissions in 1997 is from Indonesian forest fires due to changes in land use.

Global Carbon Project: Global Carbon Budget Presentation

About the data

The Global Carbon Project data for human emissions is the sum of the fossil CO2 emissions plus land-use change emissions. The values for 2023 are projections by the Global Carbon Project. The 2023 land-use projection is only given for changes in net land-use emissions. The Global Carbon Project only projected changes in land-use emission.

The fossil data is based on four main datasets containing global and national CO2 emissions. They estimate an uncertainty in global fossil CO2 emissions of ±5%.

Land-use change emissions are based on three bookkeeping models, and these models also estimate the land-use change absorption. There are large uncertainties in the land-use values before 1960.

Data sources

Global Carbon Budget 2023 Global Carbon Budget
Credits: Friedlingstein et al., 2023b, ESSD, full reference below**Update cycle: yearlyDelay: ~ 10 months after end of a year. Current year values estimates published in November.Reference: ** Friedlingstein, P., O'Sullivan, M., Jones, M. W., Andrew, R. M., Bakker, D. C. E., Hauck, J., Landschützer, P., Le Quéré, C., Luijkx, I. T., Peters, G. P., Peters, W., Pongratz, J., Schwingshackl, C., Sitch, S., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S. R., Anthoni, P., Barbero, L., Bates, N. R., Becker, M., Bellouin, N., Decharme, B., Bopp, L., Brasika, I. B. M., Cadule, P., Chamberlain, M. A., Chandra, N., Chau, T.-T.-T., Chevallier, F., Chini, L. P., Cronin, M., Dou, X., Enyo, K., Evans, W., Falk, S., Feely, R. A., Feng, L., Ford, D. J., Gasser, T., Ghattas, J., Gkritzalis, T., Grassi, G., Gregor, L., Gruber, N., Gürses, Ö., Harris, I., Hefner, M., Heinke, J., Houghton, R. A., Hurtt, G. C., Iida, Y., Ilyina, T., Jacobson, A. R., Jain, A., Jarníková, T., Jersild, A., Jiang, F., Jin, Z., Joos, F., Kato, E., Keeling, R. F., Kennedy, D., Klein Goldewijk, K., Knauer, J., Korsbakken, J. I., Körtzinger, A., Lan, X., Lefèvre, N., Li, H., Liu, J., Liu, Z., Ma, L., Marland, G., Mayot, N., McGuire, P. C., McKinley, G. A., Meyer, G., Morgan, E. J., Munro, D. R., Nakaoka, S.-I., Niwa, Y., O'Brien, K. M., Olsen, A., Omar, A. M., Ono, T., Paulsen, M., Pierrot, D., Pocock, K., Poulter, B., Powis, C. M., Rehder, G., Resplandy, L., Robertson, E., Rödenbeck, C., Rosan, T. M., Schwinger, J., Séférian, R., Smallman, T. L., Smith, S. M., Sospedra-Alfonso, R., Sun, Q., Sutton, A. J., Sweeney, C., Takao, S., Tans, P. P., Tian, H., Tilbrook, B., Tsujino, H., Tubiello, F., van der Werf, G. R., van Ooijen, E., Wanninkhof, R., Watanabe, M., Wimart-Rousseau, C., Yang, D., Yang, X., Yuan, W., Yue, X., Zaehle, S., Zeng, J., and Zheng, B.: Global Carbon Budget 2023, Earth Syst. Sci. Data, 15, 5301–5369,, 2023.