Six days before the COP26 on climate in Glasgow, the UN is sounding the alarm on greenhouse gas concentrations.

The three main greenhouse gases - CO2, methane (CH4) and nitrous oxide (N2O), peaked in 2020. The annual rate of increase in concentrations of each of these gases has even exceeded the average of the period 2011-2020.

According to the latest bulletin from the World Meteorological Organization (WMO), the Amazon has lost its capacity to absorb CO2 and part of it "is no longer a sink but a source of carbon".

"It is alarming and it is linked to deforestation in the region," WMO Secretary General Petteri Taalas said at a press conference.

About half of the carbon dioxide (CO2) emitted by human activities today remains in the atmosphere.

The rest is absorbed by the oceans and terrestrial ecosystems, but the WMO fears that these CO2 sinks are reduced as a result of deforestation and warming waters, and their acidification.

Risk of a warming of 4 degrees "by the end of the century"

The economic slowdown imposed by the Covid-19 pandemic "has not had a perceptible impact" on the level and progression of greenhouse gases in the atmosphere, despite a temporary decline in new emissions, explains the OMM.

"At the rate of increasing greenhouse gas concentrations, the rise in temperatures at the end of the century will be far above the objectives of the Paris Agreement, 1.5 to 2 degrees Celsius above pre-industrial levels .

We are very far from the goal ”, warned Petteri Taalas.

"If we continue to use fossil resources indefinitely, we could achieve a warming of around 4 degrees by the end of the century," he warned.

From the combustion of fossil fuels and the production of cement

The UN hopes world leaders in Glasgow take action to keep the planet on a bearable warming trajectory in the coming years, as data shows CO2 levels continued to rise in 2021. And CO2, which comes mainly from the combustion of fossil fuels and the production of cement, is by far the main cause of this warming.

Last year, its concentration was 413.2 ppm (parts per million), 149% above the pre-industrial level.

“It's not just a chemical formula and numbers on a graph.

This has massive repercussions on our daily life and our well-being, on the state of the planet and on the future of our children and grandchildren ”, alerted Petteri Taalas.

CO2 remains in the atmosphere for centuries

Methane, of which about 60% of atmospheric emissions are of human origin (ruminant farming, rice cultivation, landfills, etc.), and nitrous oxide, of which about 40% of emissions into the atmosphere are of human origin (fertilizers and manure) also reached peaks in concentration in 2020. As for radiative forcing (the capacity of the Earth to conserve energy from the Sun or to send it back into space), which has the effect of warming the climate, it increased by 47% between 1990 and 2020.

Global temperature will continue to rise as long as emissions continue.

And, since CO2 remains in the atmosphere for centuries and even longer in the ocean, the warming already observed will persist for several decades, even if net emissions were reduced to zero quickly, warns the WMO.

This report shows that the climate is "out of control" despite warnings from experts, underlines Euan Nisbet, researcher at the Royal Holloway University of London: "The disaster is approaching, but we can not prevent it, all that the 'we can do, that's howling'.

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