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Atmospheric greenhouse gas concentrations (CSI 013/CLIM 052) - Assessment published Jan 2012

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Generic metadata


Climate change Climate change (Primary topic)

greenhouse gases | climate change | csi | kyoto protocol
DPSIR: State
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • CSI 013
  • CLIM 052
Temporal coverage:

Key policy question: What is the trend of greenhouse gas concentrations in the atmosphere? Will they remain below 450 ppm CO2-equivalent to give a 50% probability that the global temperature rise will not exceed 2 degrees Celsius above pre-industrial levels?

Key messages

  • The global average concentrations of various greenhouse gases in the atmosphere have reached the highest levels ever recorded, and concentrations continue to increase. The combustion of fossil fuels from human activities and land-use changes are largely responsible for this increase.
  • The concentration of all GHGs, including cooling aerosols that are relevant in the context of the 2oC temperature target, reached a value of 399 ppm CO2 equivalents in 2009. 
  • The concentration in 2009 of the six greenhouse gases (GHG) included in the Kyoto Protocol has reached 439 ppm CO2 equivalent,  an increase of 160 ppm (around +58%) compared to pre-industrial levels. 
  • The concentration of CO2, the most important greenhouse gas, reached a level of 386 ppm by 2009, and further increased to 389 ppm in 2010. This is an increase of approximately 110 ppm (around +39%) compared to pre-industrial levels.


Contribution of the different GHGs as included in the Kyoto and Montreal protocol to the overall greenhouse gas concentration in 1950, 1990 and 2009

Note: The size of the pies depicts the size of the relative increase in GHG concentration

Data source:
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Atmospheric concentration of CO2 (ppm)

Note: The figure shows the atmospheric concentration of CO2

Data source:
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Atmospheric concentration of CH4 (ppb)

Note: The figure shows the atmospheric concentration of CH4

Data source:
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Atmospheric concentration of N2O (ppb)

Note: The concentrations of the individual GHGs under the Kyoto protocol have reached new highs in 2009 The figure shows the atmospheric concentration of N2O

Data source:
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Key assessment

Greenhouse gases (GHG) can intercept solar radiation and in such a way affect the climate system. In order to control the emissions of such gases, many of them are included within different international agreements, including the UNEP Montreal Protocol on Substances that deplete the Ozone layer (1987) and the Kyoto Protocol to the UNFCCC which aims to limit global warming (1997)).

  • GHG in the Kyoto Protocol are: Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and three fluorinated gasses (HFC, PFC, SF6)
  • GHG in the Montreal Protocol are three other groups of fluorinated gases: CFCs, HCFCs and CH3CCl3
  • In addition, GHG exist that are not included in global treaties, here called non-protocol gases (NPG), including stratospheric and tropospheric ozone (O3), aerosols such as black carbon, and water vapour. 

The concentration of greenhouse gases (GHG) in the atmosphere has increased during the 20th century, extremely likely [1] caused mainly by human activities related to the use of fossil fuels (e.g. for electric power generation), agricultural activities and land-use change (mainly deforestation) (IPCC, 2007a). The increase of all GHG gases has been particularly rapid since 1950. The first 50 ppm increase above the pre-industrial value of carbon dioxide (CO2), the most important human greenhouse gas, was reached in the 1970s more than 200 years since pre-industrial times (i.e. before 1750), whereas the second 50 ppm increase occurred after just approximately  30 years.

Six GHGs are included in the Kyoto Protocol. Their overall concentration in the atmosphere has reached 439 ppm CO2-equivalent in 2009, an increase of about 160 ppm compared to pre-industrial times (Figure 1). Changes in atmospheric CO2 contributed by far most of the increase (about 67% of the increase from pre-industrial period). When translating the overall 450 ppm CO2-equivalent limit into a limit just for the Kyoto gases only, this means only a further 45 ppm CO2-equivalent increase is possible (with an uncertainty range of  0 – 94 ppm CO2-equivalent).

To evaluate the GHG concentration in the atmosphere in relation to temperature change, it is important to consider all greenhouse gases, i.e. the long-living GHGs under the Kyoto Protocol, those under the Montreal Protocol (direct and indirect), as well as ozone, water vapour and aerosols (IPCC, 2007a). Considering these gases, the total CO2-equivalent concentration reached a level of 399 ppm CO2 eq. in 2009 [2] (Figure 2). The annual concentration increase over recent years has been considerably lower than for earlier years due to the economic crisis (from around 2.3 ppm CO2 eq.yr-1 between 2000 and 2005 to 1.1 ppm CO2 eq.yr-1 in 2009). 

The contribution of tropospheric ozone to the climate system is considered to be stable in the recent decades given its large annual and spatial variation (IPCC, 2007a). Long-term data series on tropospheric ozone are difficult to develop due to the scarcity of representative observing sites with long records and the large spatial heterogeneity (IPCC, 2007a). Overall, assuming a concentration threshold of 450 ppm CO2 equivalents may result in a 2oC temperature change means concentrations can only further increase by about 50 ppm before this threshold value is exceeded. Assuming the 2000-2009 trend of annual increase of total GHG concentrations will also continue in the coming years, the threshold value may be exceeded in less than 25 years. The lower band of the uncertainty range may be exceeded already within the next few years, whereas it may take more than 50 years before the upper uncertainty band is exceeded.

Excluding water vapour, ozone and aerosols, the total concentration of the remaining, long-lived GHGs has increased from 278 in pre-industrial times to 461 ppm CO2 equivalents in 2009. This is about 183 ppm higher than pre-industrial levels. That this concentration is higher than when all gases are considered is caused by the overall cooling effect of aerosols - although certain aerosols act in an opposite manner by enhancing the warming. Overall, aerosols are compensating for around 45% of the current warming induced by the Kyoto and Montreal GHGs. Aerosols have a relatively short lifetime. Due to the overall cooling effect of aerosols, the additional space for long-living GHGs such as CO2 will become smaller before exceeding 450 ppm CO2 equivalents when the aerosol concentrations will continue to decrease, for example as result of non-climate related policy measures. The Montreal Protocol gases contributed as a group about 10% to the current warming (Figure 3). The concentrations of these gases have peaked around the millennium change and have now started to decline due to natural removal processes (IPCC, 2007a).

The concentrations of the individual GHGs under the Kyoto protocol have reached new levels in 2009 (Figure 4,5 and 6). The CO2 concentration reached a level of 386 ppm in that year, and increased further in 2010 to 389 ppm (Figure 4). This is an increase of about 110 ppm (+38%) compared to the pre-industrial levels (i.e. before 1750) (NOAA, 2011). The present CO2 concentration has not been exceeded during the past 420 000 years and possibly not even during the past 20 million years (IPCC, 2007a). The concentration of methane (CH4) has increased to 1793 parts per billion (ppb) in 2009 (+156% from pre-industrial levels), a value which also has not been exceeded during the past 420 000 years (Figure 5). After nearly a decade of no growth or even decrease, the atmospheric CH4 has increased during the past three years. The reasons for this renewed growth are not fully understood, but human-induced sources such as growing industrialisation in Asia, increasing wetland emissions due to land-use changes, biomass burning, as well as increases from natural sources from northern latitudes and the tropics (e.g. CH4 releases from thawing permafrost) (Dlugokencky et al., 2009; Mascarelli, 2009; Shakhova et al, 2010) are considered potential causes (WMO, 2010). The nitrous oxide (N2O) concentration in 2009 was 322 ppm (Figure 6), up 0.6 ppb from the year before and 19% above the pre-industrial level. This concentration has not been exceeded during at least the past 1 000 years.  The concentrations of the F-gases within the scope of the Kyoto Protocol (HFCs, PFCs and SF6) have increased by large factors (between 1.3 and 6.4, depending on the gas) between 1999 and 2009. These gases are very effective absorbers of radiation and even small amounts can significantly affect the climate system. Their contribution to the total climate forcing is rapidly increasing in the past years.

[1] Defined as >95% probability (IPCC, 2007)

[2] More recent data are not available for the annual-average concentration except for CO2, for which data for 2010 are available

Data sources

More information about this indicator

See this indicator specification for more details.

Contacts and ownership

EEA Contact Info

John Van Aardenne


EEA Management Plan

2011 1.3.3 (note: EEA internal system)


Frequency of updates

Updates are scheduled every 1 year in January-March (Q1)
Document Actions
European Environment Agency (EEA)
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