Concentrations of the main greenhouse gases in the atmosphere - carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) - all reached new records in 2021, according to a report published by the American Meteorological Society on Wednesday 31 August.
According to the document compiled by the National Environmental Information Centres of the US National Oceanic and Atmospheric Administration (NOAA), the global annual average concentration of CO2 in the atmosphere was 414.7 parts per million (ppm) last year, 2.3 ppm higher than in 2020.
This is the “the highest measured in the modern observational records as well as the highest in at least the last million years based on paleoclimatic records”, the report says.
For nitrous oxide, the level reached 334.3 parts per billion (ppb) following an annual increase of 1.3 ppb in 2021 - the third highest increase since 2001.
The annual average concentration of methane in the atmosphere has risen to an unprecedented level since measurements began (+18 ppb in the year 2021).
In addition to these new records in atmospheric greenhouse gas concentrations, the report shows that global sea levels and ocean heat content also reached record highs in 2021.
See the report: https://aeur.eu/f/2wa (Original version in French by Damien Genicot)