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Atmospheric greenhouse gas concentrations (CSI 013) - Assessment published Nov 2010

Indicator Assessment Created 19 Aug 2010 Published 08 Nov 2010 Last modified 11 Sep 2012, 04:51 PM
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Generic metadata


Climate change Climate change (Primary topic)

soer2010 | csi | climate change | greenhouse gases | thematic assessments | kyoto protocol | understanding climate change
DPSIR: State
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • CSI 013
Temporal coverage:
Geographic coverage:
Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, United Kingdom

Key policy question: What is the trend in greenhouse gas concentration in the atmosphere? Will it remain below 450 ppm CO2-equivalent giving 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 gasses in the atmosphere reached their highest levels ever recorded, and continue increasing. The combustion of fossil fuels from human activities and land-use changes are largely responsible for this increase.
  • The concentration in 2008 of the six greenhouse gases (GHG) included in the Kyoto Protocol has reached 438 ppm CO2 equivalent, which is an increase of 160 ppm compared to the pre-industrial level. Considering all GHGs (incl. ozone and various cooling aerosols), the concentration has reached a value of 399 ppm CO2 equivalents in 2008, which is 121 ppm higher than in pre-industrial times. The concentration of CO2 -the most important greenhouse gas- has reached in 2008 a level of 385 ppm, and in 2009 387 ppm. This is an increase of nearly 110 ppm compared to the pre-industrial level.
  • Without climate policy, the overall concentration of the six Kyoto gasses is projected to increase up to 638-1360 ppm CO2 -equivalent by 2100, whereas the concentration of all GHGs may increase up to 608-1535 ppm CO2 -equivalent.  The global atmospheric GHG concentration of 450 ppm CO2-equivalent could already become exceeded up 2015 (depending on climate policy and definitions)

    Measured and projected concentration of all greenhouse gases (left) and Kyoto greenhouse gases (right)

    Note: Graphs show observed and projected green house gases. Projections are made using all main IPCC SRES scenarios

    Data source:


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    Key assessment

    The concentration of greenhouse gases (GHG) in the atmosphere has increased during the 20th century, extremely likely*  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). The increase of all GHG gasses has been particularly rapid since 1950. The first 50 ppm increase above the pre-industrial value of carbon dioxide (CO2) for example, was reached in the 1970s after more than 200 years, whereas the second 50 ppm was achieved in about 30 years. In the recent 10 years the highest average growth rate has been recorded for any decade since atmospheric CO2 measurements began (IPCC, 2007). This increase was nearly entirely caused by human activities (of which about two third caused by fossil fuel use and one third by land-use change/deforestation) (IPCC, 2007). The CO2-equivalent concentration of the six greenhouse gases included in the Kyoto Protocol (i.e. CO2, CH4, N2O, HFC, PFC, SF6) reached 438 ppm CO2-equivalent in 2008, an increase of 160 ppm from the pre-industrial level. According to the NOAA Annual Greenhouse Gas Index (AGGI), the total radiative forcing by all long-lived greenhouse gases (carbon dioxide (CO2), methane (CO4), nitrous oxide (N2O), CFC-12, CFC-11, and various lesser gases) has increased by 26% since 1990. CO2 contributed about 64% to the overall global radiative forcing from the pre-industrial period, and 85% to the increase in radiative forcing over the past decade (NOAA, 2009). Considering all long living greenhouse gasses (i.e. the Kyoto Gasses plus the CFCs & HCFCs, that are included in the Montreal Protocol), a level of 466 ppm CO2-equivalents has been reached in 2008. Adding, finally, ozone and various aerosols, the GHG concentration has reached a level of 399 ppm CO2 equivalents in 2008. Thus, aerosols are important for the global climate, since they have in general a strong cooling affect - although some aerosols enhance the warming. In total aerosols are compensating for about 70% of the climate forcing by CO2. Note that these aerosols have a relative short lifetime, the emissions will be reduced due to non-climate related policy measures and as such their importance for the future climate will diminish. Likewise, the Montreal Protocol gases (CFCs, HCFCs, and CH3CCl3) as a group still contributed significantly (about 17%) to the current warming. Also their contribution is likely to decrease in the near-term future due to policy measures (IPCC, 2007a).

    Assessing the role of the individual greenhouse gasses, concentrations up to 2008 of CO2, methane (CH4) and nitrous oxide (N2O) have increased by 38%, 156%, and 15%, respectively, compared with the pre-industrial era (before 1750). The CO2 concentration –the most important greenhouse gas- has reached in 2008 a level of 385 ppm, and in 2009 386 ppm (=39%). This is an increase of nearly 110 ppm compared to the pre-industrial level (  The present CO2 concentration has not been exceeded during the past 420 000 years and may be even not even during the past 20 million years. The CO2 increase is nearly entirely caused by human activities (of which about 2/3 caused by fossil fuel use, 1/3 due to land-use change). Humans are also directly responsible for about two third (mainly fossil fuel exploitation, rice agriculture, biomass burning, landfills) and one third (as fuel combustion, biomass burning, fertilizer use and some industrial processes) of the increase in CH4 and N2O, respectively. The concentration of CH4 has increased up to 1790 part per billion (ppb), a value have also not been exceeded during the past 420 000 years. The increase (0.4% both in 2007 and 2008, WMO, 2009) is remarkable after nearly a decade with no increase or even decrease. Next to growing industrialization in Asia, rising wetland emissions due to land-use changes, and biomass burning, a cause could be CH4 releases from thawing permafrost (Dlugokencky etla, 2009; Mascarelli, 2009; Shakhova et al, 2010). The present N2O concentration (now 322 ppb, plus 1 ppb compared to 2007) has not been exceeded during at least the past 1 000 years. The fluorine-containing Kyoto Protocol gases (HFCs, PFCs and SF6) are very effective absorbers of radiation and as such even small amounts can affect significantly the climate system. Their concentrations have increased by large factors (between 1.3 and 6.4, depending on the gas) between 1998 and 2008. As such their role in the total climate forcing is rapidly increasing in the past years. Concentrations of different Montreal Protocol gases (i.e. CFCs, HCFCs, and CH3CCl3) have peaked around the millennium change and have are started to decline due to natural removal processes (IPCC, 2007a). Finally, the concentration of stratospheric ozone became stable (thus the contribution to the climate system is decreasing) in the recent decades, whereas assessments of long-term trends in tropospheric ozone are difficult due to the scarcity of representative observing sites with long records and the large spatial heterogeneity (IPCC, 2007a).

    The IPCC (2001, 2007a) showed various projected future greenhouse gas concentrations for the 21st century, varying due to a range of scenarios of socio-economic, technological and demographic developments (Figure 1, Table 1). These SRES scenarios assume no implementation of specific climate-driven policy measures. Under these scenarios, the overall concentration of the six Kyoto gasses is projected to increase up to 638-1360 ppm CO2-equivalent by 2100, whereas the concentration of all GHGs (incl. aerosols) may increase up to 608-1535 ppm CO2-equivalent by 2100 (Fig. 1). Note the importance of the non-Kyoto gasses (especially aerosols) is projected to strongly decrease, resulting in decreasing differences between only-Kyoto and all-GHG projections, with the exception of the A1FI scenario (where especially Montreal gasses and ozone remain high).  

    Given these SRES projections without climate policy, a global atmospheric GHG concentration of 450 ppm CO2- equivalent may become exceeded between 2010-2015 (in case of Kyoto gasses only) or between 2020-2030 (all GHGs). A level of 550 ppm CO2-equivalent may become exceeded a decade later (Figure 1). Stringent climate policies, leading to substantial global emission reductions, are needed to remain below these targets or return back to these levels after an overshoot. Although uncertain, if such policies would become implemented –in combination with moderate baseline emissions- this could lead to a  peak at 455 ppm  CO2-equiv. around 2050, followed by a decline down to about 427 ppm CO2 equivalent  in 2100 (Moss et al, 2010, Table 1) (considering all gasses).

    [1] 2009 concentration levels are yet not available for the other greenhouse gasses.

    * Defined as >95% probability (IPCC, 2007a)

    Table 1: Projected changes in atmospheric GHG concentration (considering either Kyoto gasses only or all GHGs)















    Kyoto only




































    all GHGs









    (incl. aerosols)



















    Source: IPCC, 2001, 2007a for the SRES scenarios; Moss et al, 2010 & Van Vuuren pers. Comm.. for the RCP scenario

      1This RCP2.6 scenario assumes stringent climate policy and a moderate socio-economic development

      22009 concentration levels are yet not available for the other greenhouse gasses. 

    Data sources

    More information about this indicator

    See this indicator specification for more details.

    Contacts and ownership

    EEA Contact Info

    Blaz Kurnik


    EEA Management Plan

    2010 2.0.1 (note: EEA internal system)


    Frequency of updates

    Updates are scheduled once per year in January-March (Q1)
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