CO2 atmospheric concentration

  •  30/11/2021

In 2020, the atmospheric concentration of CO2 was on average at 412.45 ppm. To achieve the sustainable development goal, this indicator must stabilize at a level as low as possible. This indicator is not assessed because Belgian policies have very little influence on this world-level indicator.

The chart will appear within this DIV.

CO2 atmospheric concentration

parts per million

//: Average Growth Rates

Dlugokencky Ed and Tans Pieter (2021), NOAA/ESRL, (consulted on 02/06/2021).

Definition: this indicator gives the average concentration of carbon dioxide (CO2) in the atmosphere. The concentration is expressed in parts per million (ppm - calculated as a volume, i.e. as a molar concentration in dry air). This indicator is measured at the global level because atmospheric currents rapidly homogenize the CO2 emitted.

CO2 is the main cause of global warming. The IPCC (Intergovernmental Panel on Climate Change) estimates the total radiative forcing, i.e. the increase in energy received at ground level due to the increase in the atmospheric concentration of greenhouse gases (GHG), at 2.29 W/m² in 2011 (IPCC, 2013, p.14). The contribution of CO2 to this total is 1.68 W/m². Second comes methane, with a contribution of 0.97 W/m² to radiative forcing. Aerosols also play an important part, as they absorb some of the sun's rays. The increase in their concentration therefore negatively affects the total forcing (-0.82 W/m²).

Only CO2 is measured by this indicator since it has the largest contribution and because its lifetime in the atmosphere is much longer (about 100 years) than that of other greenhouse gases such as methane or nitrous oxide. The data come from the US National Oceanic and Atmospheric Administration.

Goal: the aim is to reduce CO2 emissions to stabilize the concentration of GHGs and in particular CO2 in the atmosphere at the lowest possible level. See the GHG emissions and Non-ETS GHG emissions indicators.

By reducing its CO2 emissions, Belgium contributes to the global effort to stabilize the concentration of GHGs in the atmosphere.

The Paris Agreement (UNFCCC, 2015) sets a target of limiting the increase in global average temperature to a maximum of 1.5°C or 2°C above pre-industrial levels. The IPCC has drawn up four climate evolution scenarios. Among these scenarios, those aiming to limit the increase to 1.5°C to 2°C require a slowing down in the increase in CO2 concentrations and then a stabilization. In the most optimistic scenario, consistent with the 1.5°C target (RCP2.6 scenario), the atmospheric concentration of CO2 reaches 443 ppm in 2050 and then decreases. In a second temperature stabilization scenario, but at a higher level (the probability of exceeding 2°C is greater than that of remaining below it - RCP4.5 scenario), the atmospheric CO2 concentration reaches 487 ppm in 2050 and stabilizes in the long term at 543 ppm (Meinshausen et al., 2011; IPCC, 2013). The other IPCC scenarios lead to higher temperature increases and are not considered here.

Evolution: the atmospheric concentration of CO2 has increased continuously since the beginning of measurements in the 1950s. In 1990, it was 354.05 ppm and in 2020, it reached 412.45 ppm. These levels should be compared to those of the pre-industrial period. For the 1750 reference year, the atmospheric concentration of CO2 is estimated at 278 ppm (IPCC 2013, p.50).

UN indicator: the selected indicator does not correspond to any monitoring indicator for the SDGs, but is related to goal 13 because the fight against climate change requires a significant reduction in CO2 emissions.


  • General

    • SDGs, Sustainable Development Goals: United Nations (2015), Transforming our world: the 2030 Agenda for Sustainable Development. Resolution adopted by the General Assembly on 25 September 2015, document A/RES/70/1.

    • Indicators: United Nations (2017), Work of the Statistical Commission pertaining to the 2030 Agenda for Sustainable Development. Resolution adopted by the General Assembly on 6 July 2017, document A/RES/71/313.

    • UN Sustainable Development Knowledge Platform: (consulted on 26/04/2019).

    • Sustainable Development Goal indicators website: (consulted on 26/04/2019).
  • Specific

    • IPCC (2013), Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (Stocker T.F., Qin D., Plattner G.-K., Tignor M., Allen S.K., Boschung J., Nauels A., Xia Y., Bex V. and Midgley P.M. - eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

    • Meinshausen M., Smith S. J., Calvin K., Daniel J. S., T. Kainuma M. L., Lamarque J-F., Matsumoto K., Montzka S. A., Raper S. C. B., Riahi K., Thomson A., M. Velders G. J., van Vuuren D. P. P. (2011), The RCP greenhouse gas concentrations and their extensions from 1765 to 2300, Climatic Change (2011) 109:213–241.

    • UNFCCC (2015), Adoption of the Paris Agreement, Decision 1/CP.21, FCCC/CP/2015/10/Add.1, (consulted on 6/12/2019).

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