Greenhouse gases are gases such as Carbon Dioxide (CO2) and Methane (CH4) that absorb and re-emit infrared radiation. In the atmosphere, their interaction with infrared radiation ultimately leads to a warming of the atmosphere and surface.
Atmospheric concentrations of greenhouse gases reflect a balance between emissions from human activities (such as the burning of fossil fuels), natural sources, and sinks in the biosphere and ocean. Increasing levels of greenhouse gases in the atmosphere due to human activities have been the major driver of climate change since the mid-twentieth century. Global average mole fractions of greenhouse gases (as shown in the figures) are calculated from in situ observations made at multiple sites in the Global Atmosphere Watch (GAW) Programme of WMO and partner networks.
The ocean is a sink for CO2. Some of the excess CO2 in the atmosphere is absorbed by the ocean. CO2 reacts with seawater and lowers its pH. This process is known as ocean acidification.
A 1.1 Observed increases in well-mixed greenhouse gas (GHG) concentrations since around 1750 are unequivocally caused by human activities. Since 2011 (measurements reported in AR5), concentrations have continued to increase in the atmosphere, reaching annual averages of 410 parts per million (ppm) for carbon dioxide (CO2), 1866 parts per billion (ppb) for methane (CH4), and 332 ppb for nitrous oxide (N2O) in 2019. Land and ocean have taken up a near-constant proportion (globally about 56% per year) of CO2 emissions from human activities over the past six decades, with regional differences (high confidence).
In 2024, greenhouse gas mole fractions reached new highs, with globally averaged surface mole fractions of carbon dioxide (CO2) at 423.9 ± 0.2 parts per million (ppm), methane (CH4) at 1942 ± 2 parts per billion (ppb) and nitrous oxide (N2O) at 338.0 ± 0.1 ppb, respectively 152%, 266% and 125% of pre-industrial (1750) levels.
Paragraph updated: 2026-03-20 10:11
Carbon dioxide (CO2) is one of the most important greenhouse gases. The concentration of CO2 in the atmosphere is measured at stations around the world which are combined to provide a globally representative value.
The data in the above plot are available in a zip file containing a csv file for each data set.
Data file: Carbon_dioxide_data_files.zip
Checksum: fb08ef0ffe46729900c84d4709862898
Format: BADC CSV format
Original data file (external link)
Citation:
To produce the plot, the following processing steps were performed:
Methane (CH4) is an important greenhouse gas. The concentration of CH4 in the atmosphere is measured at stations around the world which are combined to provide a globally representative value.
The data in the above plot are available in a zip file containing a csv file for each data set.
Data file: Methane_data_files.zip
Checksum: b06b27ce176dad17c5c94bea206fe047
Format: BADC CSV format
Original data file (external link)
Citation:
To produce the plot, the following processing steps were performed:
Nitrous oxide (N2O) is an important greenhouse gas. The concentration of N2O in the atmosphere is measured at stations around the world which are combined to provide a globally representative value.
The data in the above plot are available in a zip file containing a csv file for each data set.
Data file: Nitrous_Oxide_data_files.zip
Checksum: 6a4d4c23f0fab32ecb8f671c9835f82d
Format: BADC CSV format
Original data file (external link)
Citation:
To produce the plot, the following processing steps were performed:
The data in the above plot are available in a zip file containing a csv file for each data set.
Data file: Carbon_dioxide_growth_rate_data_files.zip
Checksum: 308677ada4b33a024a479382863b2c1d
Format: BADC CSV format
Original data file (external link)
Citation:
To produce the plot, the following processing steps were performed:
The data in the above plot are available in a zip file containing a csv file for each data set.
Data file: Methane_growth_rate_data_files.zip
Checksum: a0471d17ba0a5f06ef4f751bd36da25c
Format: BADC CSV format
Original data file (external link)
Citation:
To produce the plot, the following processing steps were performed:
The data in the above plot are available in a zip file containing a csv file for each data set.
Data file: Nitrous_oxide_growth_rate_data_files.zip
Checksum: 25d71ffac8f86ed65ed379ed33f90644
Format: BADC CSV format
Original data file (external link)
Citation:
To produce the plot, the following processing steps were performed:
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