The industrial slowdown due to the Covid-19 pandemic has not slowed down the record increase in concentrations of CO2, the main persistent greenhouse gas in the atmosphere, the UN said on Monday 23 November.
According to the Annual Bulletin of the World Meteorological Organization (WMO), a UN agency, the concentration of carbon dioxide in the atmosphere rose sharply in 2019, with the annual average crossing the threshold of 410 parts per million, and the rise continued in 2020, as the Covid-19 pandemic forced many countries to shut down their economies.
“The drop in emissions from containment is just a small point on the long-term curve. However, we must flatten the latter in a sustainable way ”, said WMO Secretary General Petteri Taalas.
The level goes up
According to the WMO bulletin, during the most intense period of economic shutdown, daily global CO2 emissions have fallen by up to 17% due to containment.
While the duration and severity of the containment measures are still unclear, the WMO considers it very difficult to estimate the total annual reduction in emissions in 2020, but it nevertheless estimates that, according to preliminary estimates, this reduction will be of the order of 4.2% to 7.5%.
Such a reduction in emissions will not, however, lead to a decrease in atmospheric CO2 concentrations this year as these concentrations are the result of cumulative past and current emissions.
In summary, the concentration of CO2 will continue to increase this year, but at a slightly reduced rate, not exceeding the usual fluctuations in the carbon cycle seen from year to year.
The impact of greenhouse gases
“The Covid-19 pandemic will not solve the problem of climate change. However, it represents a stepping stone to launch more sustained and ambitious climate action aimed at reducing net emissions to zero by completely transforming our industries, energy systems and transport ”, by souligné Petteri Taalas.
Greenhouse gases trap heat in the atmosphere, raise temperatures and intensify extreme weather conditions, melting ice, rising sea levels and acidification of the oceans.
The three main persistent greenhouse gases – carbon dioxide, methane and nitrous oxide – again hit record levels in 2019, according to the WMO.
However, carbon dioxide, resulting in particular from the use of fossil fuels, the production of cement and deforestation, remains for centuries in the atmosphere and even longer in the oceans.
Its content in the atmosphere increased more rapidly between 2018 and 2019 than between 2017 and 2018 and than over the last ten years on average.
Like 3 to 5 million years ago
“The last time the Earth experienced a comparable CO2 content, it was 3 to 5 million years ago: the temperature was then 2 to 3 ° C higher than today and the level of the sea was 10 to 20 meters above the current level, but we were not 7.7 billion ” human beings, underlined Petteri Taalas.
As for methane, of which 60% of emissions into the atmosphere are of human origin (ruminant farming, rice cultivation, exploitation of fossil fuels, landfills, etc.), its content increased slightly less rapidly between 2018 and 2019 than between 2017 and 2018, but faster than over the past ten years on average.
Finally, the rate of increase in the concentration of nitrous oxide, both a greenhouse gas and an ozone-depleting chemical, has remained practically equal to the average of the previous ten years. 40% of its emissions into the atmosphere are of human origin (fertilizers, industrial processes, etc.), but the rest are of natural origin.
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