Greenhouse gases in the atmosphere reached a new record last year, despite coronavirus lockdowns, with an annual rate of increase above the average for 2011-2020.
That trend has continued this year, according to a report by the World Meteorological Organisation's (WMO) Greenhouse Gas Bulletin.
Concentration of carbon dioxide (CO2), the most important greenhouse gas, has now reached 413.2 parts per million in 2020 and is at 149% of pre-industrial levels.
Other greenhouse gases methane and nitrous oxide are 262% and 123% respectively of the levels seen in 1750, when human industrial activity began to disrupt Earth’s natural equilibrium.
Despite expectations, the economic slowdown from COVID did not have any discernible impact on the atmospheric levels of greenhouse gases and their growth rates, although there was a temporary decline in new emissions.
Professor Petteri Taalas, WMO secretary general, said: “The Greenhouse Gas Bulletin contains a stark, scientific message for climate change negotiators at COP26.
“At the current rate of increase in greenhouse gas concentrations, we will see a temperature increase by the end of this century far in excess of the Paris Agreement targets of 1.5-2C above pre-industrial levels. We are way off track.
“The amount of CO2 in the atmosphere breached the milestone of 400 parts per million in 2015. And just five years later, it exceeded 413 ppm.
"This is more than just a chemical formula and figures on a graph. It has major negative repercussions for our daily lives and wellbeing, for the state of our planet and for the future of our children and grandchildren.”
Last year, despite lockdowns that saw air travel plunge and kept commuters off the roads, the WMO described the drop in emissions as a "tiny blip".
The current temperature level will persist for decades, even if emissions are reduced to net zero, the WMO warned.
This will mean more extreme weather, such as intense heat and rainfall, melting ice and rising sea levels, and wide-ranging impacts on economies around the world.
The WMO warned that roughly half of the CO2 emitted by human activities remains in the atmosphere, with the other half taken up by oceans and land ecosystems – but that these "sinks" may become less effective in future.
Its research shows that from 1990 to 2020, radiative forcing – the warming effect on our climate – by long-lived greenhouse gases increased by 47%, with CO2 accounting for about 80% of this increase.
Professor Taalas said: “Carbon dioxide remains in the atmosphere for centuries and in the ocean for even longer.
"The last time the Earth experienced a comparable concentration of CO2 was 3-5 million years ago, when the temperature was 2-3C warmer and sea level was 10-20 metres higher than now. But there weren’t 7.8 billion people then.
“Many countries are now setting carbon neutral targets and it is hoped that COP26 will see a dramatic increase in commitments.
"We need to transform our commitment into action that will have an impact of the gases that drive climate change. We need to revisit our industrial, energy and transport systems and whole way of life.
"The needed changes are economically affordable and technically possible. There is no time to lose.”
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