Research by the National Oceanic and Atmospheric Administration (NOAA) shows that levels of the three most important human-caused greenhouse gases, carbon dioxide (CO2), methane and nitrous oxide, continued to rise during 2023.
During 2023 the global monitoring laboratory for NOAA collected 15,000 air samples from monitoring stations world-wide, which were then analyzed.
Samples collected by the NOAA's Global Monitoring Laboratory in 2023 for the three heat trapping gases were not quite as high as the record rises observed in recent years, but were in line with the severe increases found during the past decade.
Set out below are the findings from the NOAA monitoring.
Carbon dioxide (CO2)
The global surface concentration of CO2, averaged across all 12 months of 2023, was 419.3 parts per million (ppm), an increase of 2.8 ppm during the year. This was the 12th consecutive year CO2 increased by more than 2 ppm, extending the highest sustained rate of CO2 increases during the 65-year monitoring record. Three consecutive years of CO2 growth of 2 ppm or more had not been seen in NOAA's monitoring records prior to 2014.
Atmospheric CO2 is now more than 50% higher than pre-industrial levels.
Methane
Atmospheric methane, less abundant than CO2 but more potent at trapping heat in the atmosphere, rose to an average of 1922.6 parts per billion (ppb). The 2023 methane increase over 2022 was 10.9 ppb, lower than the record growth rates seen in other years, but still the 5th highest since renewed methane growth started in 2007.
Methane levels in the atmosphere are now more than 160% higher than their pre-industrial level.
Nitrous oxide
Levels of nitrous oxide, the third-most significant human-caused greenhouse gas, climbed by 1 ppb to 336.7 ppb. The two years of highest growth since 2000 occurred in 2020 (1.3 ppb) and 2021 (1.3 ppb). Increases in atmospheric nitrous oxide during recent decades are mainly from use of nitrogen fertilizer and manure from the expansion and intensification of agriculture.
Nitrous oxide concentrations are 25% higher than the pre-industrial levels.
GML Director Vanda Grubišić outlined "as these numbers show, we still have a lot of work to do to make meaningful progress in reducing the amount of greenhouse gases accumulating in the atmosphere".
