All official European Union website addresses are in the europa.eu domain.
See all EU institutions and bodies
An official website of the European Union | How do you know?
Environmental information systems
The total concentration of greenhouse gases and other forcing agents, including cooling aerosols, reached 472 parts per million CO2 equivalents in 2021. This is within range the International Panel on Climate Change states peak level 'should not be exceeded if — with a 67% likelihood and not allowing a temperature overshoot — the global temperature increase is to be limited to 1.5oC above pre-industrial levels'. When allowing for a temperature overshoot, the peak level could be exceeded before 2026. The peak concentrations corresponding to a temperature increase of 2oC by 2100 could be exceeded before 2032.
Figure 1. Observed trends in total greenhouse gas concentration levels between 1860 and 2021, considering all greenhouse gases and other forcing agents (including aerosols)
This indicator assesses the combined global atmospheric concentration of all greenhouse gases and forcing agents, and evaluates how the status of and trend in that concentration relate to scientific knowledge and policy ambitions for limiting global temperature increase at the end of the century. The objective of the 2015 Paris Climate Agreement is ‘to hold the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels’ .
An outcome of the agreement in Glasgow (2021), Sharm el-Sheikh (2022) and Dubai (2023) has been to ‘pursue efforts to limit the temperature increase to 1.5oC’. It is important to consider all gases and other forcing agents using the so-called ‘CO2 equivalent’ (CO2e); (see supporting information). Note that some of the gases, such as sulphate aerosols, have a negative forcing (i.e. a cooling effect).
Considering all greenhouse gases and other forcing agents (including aerosols), the total CO2e concentration reached 472ppm in 2021, which is about 50ppm more than 10 years ago (Figure 1) and about 192ppm more than in pre-industrial times. The increase was 4.0ppm, the lowest in the last ten years. Assessing the contribution of the various groups of greenhouse gases has shown that by far the most forcing is caused by gases covered by the Kyoto Protocol (KPGs).
The annual average concentration of CO2 reached 414ppm and 417ppm in 2021 and 2022 respectively (+137ppm or +148%) above pre-industrial levels, while the average concentration of CH4 reached 1,893ppb in 2021 (plus 1,173ppb or +265%). As a group, the gases covered by the Montreal Protocol (MPGs) contributed about 31ppm to climate forcing in 2021.
The non-protocol gases (NPGs) have a net cooling effect overall. In 2021, this effect amounted to nearly 51ppm CO2e, and as such, compensated for about 21% of the forcing induced by other greenhouse gases. Note that the forcing (cooling) trend of NPGs has been decreasing since 2010, especially due to lower concentration of sulphur dioxide and its cooling effect . Further reading is available here.
Figure 2. Peak and 2100 concentrations of total greenhouse gases in the atmosphere consistent with a 67% probability of keeping the average global temperature increase below 1.5°C (left) and 2°C (right)
Pathways developed by the IPCC show concentrations of atmospheric greenhouse gases in relation to specific temperature increases. These pathways show (1) peak concentrations that should not be exceeded to ensure that (2) CO2e concentrations in 2100 remain compatible with limiting the temperature increase to 1.5°C or 2°C above pre-industrial levels.
According to the IPCC’s most precautionary peak and 2100 concentration levels — those corresponding to a 67% chance of staying below target values without allowing a temperature overshoot in that period — global greenhouse gas concentrations most not exceed 465 (range 445-485) ppm CO2e and should return to 411 (390-430) ppm by 2100 to limit the increase to 1.5°C; for the 2°C limit, the corresponding values are 505 (470-540) ppm and 480 (460-500) ppm CO2e, respectively.
As such the concentration in 2021 of 472ppm CO2e is close to the upper limit of the mentioned range of (most-precautional) peak concentration that should not be exceeded to limit the global temperature increase to 1.5°C above pre-industrial times (445-485 ppm CO2e) (figure 2).
When allowing a temporary temperature overshoot and considering the present decadal growth rate, the peak concentration threshold could be exceeded at maximum around 2028. So, there are few years left to stabilise the concentration, but concentrations must reduce further afterwards. In the case of the 2°C limit, the peak concentration will be reached around 2028-2031. Taking into account uncertainty ranges (see supporting information), peak concentrations will be reached within 0-8 years (for +1.5°C) or from 3-13 years (for +2°C) (after to 2021).