Introduction

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.

What the IPCC says

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).

Key messages

Atmospheric concentration of carbon dioxide

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: 2026-03-17 14:18

Dataset and processing details

Carbon dioxide

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: 1baa7015ebaf050cf7967fab55c0b278 Copy
Format: BADC CSV format

WDCGG

Original data file (external link)

Citation:

• WMO Greenhouse Gas Bulletin, No.18, 2022. 26 October 2022 ISSN 2078-0796.

To produce the plot, the following processing steps were performed:

• Data set created from file ['co2_annual_20251016.csv'] downloaded from ['https://gaw.kishou.go.jp/static/publications/global_mean_mole_fractions/2025/co2_annual_20251016.csv'] at ['2025-10-17 10:10:39']

Methane

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: 06c0a89018e07c2b82fe7646258db73d Copy
Format: BADC CSV format

WDCGG

Original data file (external link)

Citation:

• WMO Greenhouse Gas Bulletin, No.18, 2022. 26 October 2022 ISSN 2078-0796.

To produce the plot, the following processing steps were performed:

• Data set created from file ['ch4_annual_20251016.csv'] downloaded from ['https://gaw.kishou.go.jp/static/publications/global_mean_mole_fractions/2025/ch4_annual_20251016.csv'] at ['2025-10-17 10:10:27']

Nitrous Oxide

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: cb326434a2b1492b422e15a6dc152b4a Copy
Format: BADC CSV format

WDCGG

Original data file (external link)

Citation:

• WMO Greenhouse Gas Bulletin, No.18, 2022. 26 October 2022 ISSN 2078-0796.

To produce the plot, the following processing steps were performed:

• Data set created from file ['n2o_annual_20251016.csv'] downloaded from ['https://gaw.kishou.go.jp/static/publications/global_mean_mole_fractions/2025/n2o_annual_20251016.csv'] at ['2025-10-17 10:10:49']

Carbon dioxide growth rate

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: 8ac14f0854761c56be9225e00457052d Copy
Format: BADC CSV format

WDCGG

Original data file (external link)

Citation:

• WMO Greenhouse Gas Bulletin, No.18, 2022. 26 October 2022 ISSN 2078-0796.

To produce the plot, the following processing steps were performed:

• Data set created from file ['co2_annual_20251016.csv'] downloaded from ['https://gaw.kishou.go.jp/static/publications/global_mean_mole_fractions/2025/co2_annual_20251016.csv'] at ['2025-10-17 10:10:44']

Methane growth rate

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: 74e5cfa9cb2139264e62f948d944540e Copy
Format: BADC CSV format

WDCGG

Original data file (external link)

Citation:

• WMO Greenhouse Gas Bulletin, No.18, 2022. 26 October 2022 ISSN 2078-0796.

To produce the plot, the following processing steps were performed:

• Data set created from file ['ch4_annual_20251016.csv'] downloaded from ['https://gaw.kishou.go.jp/static/publications/global_mean_mole_fractions/2025/ch4_annual_20251016.csv'] at ['2025-10-17 10:10:34']

Nitrous oxide growth rate

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: 5ae489d75b915cb700152639cb7f9920 Copy
Format: BADC CSV format

WDCGG

Original data file (external link)

Citation:

• WMO Greenhouse Gas Bulletin, No.18, 2022. 26 October 2022 ISSN 2078-0796.

To produce the plot, the following processing steps were performed:

• Data set created from file ['n2o_annual_20251016.csv'] downloaded from ['https://gaw.kishou.go.jp/static/publications/global_mean_mole_fractions/2025/n2o_annual_20251016.csv'] at ['2025-10-17 10:10:54']

Sulphur Hexafluoride

The data in the above plot are available in a zip file containing a csv file for each data set.

Data file: Sulphur_Hexafluoride_data_files.zip
Checksum: 30b06caa4248fe96997dbcfbd29ac133 Copy
Format: BADC CSV format

NOAA

Original data file (external link)

Citation:

• Lan, X., K.W. Thoning, and E.J. Dlugokencky: Trends in globally-averaged CH4, N2O, and SF6 determined from NOAA Global Monitoring Laboratory measurements. Version 2026-02, https://doi.org/10.15138/P8XG-AA10.

Data citation: https://doi.org/10.15138/P8XG-AA10

To produce the plot, the following processing steps were performed:

• Data set created from file ['sf6_annmean_gl.txt'] downloaded from ['https://gml.noaa.gov/webdata/ccgg/trends/sf6/sf6_annmean_gl.txt'] at ['2026-02-19 14:51:35']

Carbon Dioxide single-site series

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_single-site_series_data_files.zip
Checksum: 874b7137901b092ea50968bfb557c87b Copy
Format: BADC CSV format

Kennaook/Cape Grim

Original data file (external link)

Data citation: https://www.csiro.au/greenhouse-gases/

Acknowledgement: https://www.csiro.au/greenhouse-gases/ Data measured at the Kennaook / Cape Grim Baseline Air Pollution Station (KCGBAPS), located near the north-west tip of Tasmania, Australia. KCGBAPS is funded and managed by the Australian Bureau of Meteorology, and the scientific program is jointly supervised with CSIRO Oceans & Atmosphere

To produce the plot, the following processing steps were performed:

• Data set created from file ['CapeGrim_CO2_data_download.csv'] downloaded from ['https://capegrim.csiro.au/GreenhouseGas/data/CapeGrim_CO2_data_download.csv'] at ['2026-01-22 15:53:40']
• Calculated annual average from monthly averages using arithmetic mean

Mauna Loa

Original data file (external link)

Citation:

• Keeling, C. D., Bacastow, R. B., Bainbridge, A. E., Ekdahl, C. A., Guenther, P. R., Waterman, L. S. and Chin, J. F. (1976), Atmospheric carbon dioxide variations at Mauna Loa Observatory, Hawaii. Tellus, 28: 538-551. doi:10.1111/j.2153-3490.1976.tb00701.x.

Acknowledgement: Dr. Pieter Tans, NOAA/ESRL (www.esrl.noaa.gov/gmd/ccgg/trends/) and Dr. Ralph Keeling, Scripps Institution of Oceanography (scrippsco2.ucsd.edu/).

To produce the plot, the following processing steps were performed:

• Data set created from file ['co2_annmean_mlo.txt'] downloaded from ['ftp://aftp.cmdl.noaa.gov/products/trends/co2/co2_annmean_mlo.txt'] at ['2026-01-22 15:53:43']