The ICOS-RAMCES team has just published the latest measurements of CO2 and CH4 in the atmosphere, revealing unprecedented levels. The data, from the Service National d’Observation ICOS-France-Atmosphère (SIFA), one of Europe’s largest greenhouse gas monitoring networks, highlight a worrying situation. This French contribution to the atmospheric observation network of the ICOS-ERIC European research infrastructure is essential for determining greenhouse gas balances on the European continent.
To obtain these results, the scientists rely on a network of 18 measuring stations, including 11 in mainland France, which continuously analyze concentrations of CO2, CH4 and CO, as well as various meteorological parameters (wind speed and direction, temperature, pressure and relative humidity) according to standardized protocols. Six of these stations also measure concentrations of N2O (nitrous oxide), whose data will shortly be available on the AERIS atmospheric data and services center. Analysis of the data up to the end of March 2024 reveals an uninterrupted rise in concentrations, in direct response to the continuing growth in global fossil fuel consumption. This trend is punctuated by seasonal cycles and inter-annual variations linked to exchanges with natural reservoirs such as forests, soils, wetlands and oceans, processes that scientists are seeking to better understand.
The results are particularly alarming: CO2 concentration on Amsterdam Island has crossed the 420 ppm1 threshold, 24% higher than the first measurements taken on the island in 1980. Even more alarming, the annual growth rate reached a record +3.7 ppm between April 2023 and April 2024, exceeding the previous record of +3.6 ppm observed in 2015-2016. These growth peaks coincide with El Niño2 episodes, which, by raising global temperatures, fuel numerous extreme events and disrupt CO2 exchanges with natural ecosystems (droughts, fires, etc.).
These climatic disturbances have led to a temporary acceleration in CO2 growth, in addition to the man-made emissions responsible for the rise in concentrations observed everywhere, including in very remote observatories such as Amsterdam Island and Reunion Island. Methane concentrations now exceed 1850 ppb3 on Amsterdam Island. While growth has moderated in recent months (less than 5 ppb/year), it had reached record levels between 2020 and 2022 (over 15 ppb/year).
This acceleration appears to be attributable to several factors, including high emissions from tropical wetlands and an increase in the atmospheric lifetime of methane, the latter linked to lower emissions of nitrogen oxides during the 2020 confinements.
Data are available on the AERIS portal: https://sno-ifa.aeris-data.fr/en/homepage/
Scientific contacts: Michel Ramonet () et Morgan Lopez ()
CNRS/INSU press release
https://www.insu.cnrs.fr/fr/cnrsinfo/icos-france-atmosphere-les-gaz-effet-de-serre-battent-des-records-en-2024