All values in billion tonnes of carbon per year (GtC/yr), for the globe. For values in billion tonnes of carbon dioxide (CO₂) per year, multiply the numbers below by 3.664.
1 billion tonnes C = 1 petagram of carbon (10^15 gC) = 1 gigatonne C = 3.664 billion tonnes of CO₂
Please note: The methods used to estimate the historical fluxes presented below differ from the carbon budget presented from 1959 onwards. For example, the atmospheric growth and ocean sink do not account for year-to-year variability before 1959.
Uncertainties: see the original papers for uncertainties
Cite as: Friedlingstein et al (2021; see summary tab)

Fossil fuel combustion and cement production emissions: Friedlingstein et al. (2021)
Land-use change emissions: As in Global Carbon Budget from 1959: average of three bookkeeping models: H&N (Houghton &Nassikas, 2017), BLUE (Hansis, et al., 2015) and OSCAR (Gasser et al., 2020). Cite as: Friedlingstein et al (2021; see summary tab)
Atmospheric CO₂ growth rate: Joos, F. and Spahni, R.: Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years, Proceedings of the National Academy of Science, 105, 1425-1430, 2008.
The ocean CO₂ sink prior to 1959 is the average of the two diagnostic ocean models: DeVries, T. et al., Global Biogeochemical Cycles, 28, 631-647, 2014; and Khatiwala, S et al., Biogeosciences, 10, 2169-2191, 2013.
The land sink is as in Global Carbon Budget from 1959: average of 17 dynamic global vegetation models that reproduce the observed mean total land sink of the 1990s.
Cement carbonation is the average of two estimates: Friedlingstein et al. (2021)
The budget imbalance is the sum of emissions (fossil fuel and industry + land-use change) minus (atmospheric growth + ocean sink + land sink + cement carbonation sink); it is a measure of our imperfect data and understanding of the contemporary carbon cycle.