This may be further evidence of the severity of the climate crisis. The concentrations of greenhouse gases in the atmosphere have reached record levels in 2021, according to the annual bulletin published by the World Meteorological Organization (WMO) on Wednesday, October 26. This additional greenhouse effect leads to an increase in global temperature (+1.2 °C since pre-industrial times), the multiplication of extreme events and even rise in sea level.
In 2021, the atmospheric concentration of carbon dioxide (CO2) was 416 parts per million (ppm), methane was 1,908 parts per billion (ppb) and nitrous oxide was 335 ppb, increases of 149% and 262%, respectively. and 124% compared to the pre-industrial era, when human activities did not yet disturb the natural balance of these gases in the atmosphere.
The concentration of CO2, the main greenhouse gas, has now reached levels not seen in more than 2 million years. The 2021 record is no surprise, however, as the concentrations are due to CO2 emissions, which continue to increase year after year due to human activities, particularly the exploitation of fossil fuels (coal, oil and gas) and deforestation. Thus, after the extraordinary drop in 2020 with the Covid-19 crisis, CO2 emissions have largely started to increase again in 2021 and should see a slight increase in 2022. Concentrations will therefore continue to increase worldwide in 2022.
Also read: Article reserved for our subscribers In France, global warming looks worse than expected, according to new forecasts
Only achieving CO2 neutrality, i.e. the principle that emissions must not exceed the absorptive capacity of natural sinks (forests, oceans, etc.), “allows the CO2 concentration in the atmosphere to stabilize and then slowly decrease”. recalls climatologist Pierre Friedlingstein, director of research at the CNRS, the Ecole Normale Supérieure and the University of Exeter (UK).
” It’s urgent “
Mount Chacaltaya in Bolivia, September 2021. AIZAR RALDES / AFP
Concentrations of methane, the second most common greenhouse gas, have seen an “extraordinary” increase in 2020 and 2021, the WMO reports. With an increase of 15 ppb and then 18 ppb, these are the largest increases since measurements began almost forty years ago. The cause of this increase is not clear, but several hypotheses have been put forward, relating to both biological and anthropogenic processes.
You still have 41.77% of this article to read. The following is for subscribers only.