The global Covid-19 lockdowns caused fossil carbon dioxide (CO2) emissions to decline by an estimated 2.4 billion tonne in 2020 - a record drop, say researchers.
The fall is considerably larger than previous significant decreases - 0.5 (in 1981 and 2009), 0.7 (1992), and 0.9 (1945) billion tonne of CO2 (GtCO2).
"It means that in 2020 fossil CO2 emissions are predicted to be approximately 34 GtCO2, seven per cent lower than in 2019," said study author from University of East Anglia (UEA), University of Exeter and the Global Carbon Project.
In India, where fossil CO2 emissions are projected to decrease about nine per cent, emissions were already lower than normal in late 2019 because of economic turmoil and strong hydropower generation, and the Covid-19 effect is potentially superimposed on this changing trend.
The emissions decrease appears more pronounced in the US (-12 per cent) and EU27 countries (-11 per cent), where Covid-19 restrictions accelerated previous reductions in emissions from coal use.
It appears least pronounced in China (-1.7 per cent), where the effect of Covid-19 restrictions on emissions occurred on top of rising emissions.
In the UK, which first introduced lockdown measures in March, emissions are projected to decrease by about 13 per cent.
For the rest of the world, the effect of Covid-19 restrictions occurred on top of rising emissions, with emissions this year projected to decrease by about 7 per cent.
According to the report, by December 2020, emissions from road transport and aviation were still below their 2019 levels, by approximately 10 per cent and 40 per cent, respectively, due to continuing restrictions.
Despite lower emissions in 2020, the level of CO2 in the atmosphere continues to grow - by about 2.5 parts per million (ppm) in 2020 - and is projected to reach 412 ppm averaged over the year, 48 per cent above pre-industrial levels.
"Although global emissions were not as high as last year, they still amounted to about 39 billion tonnes of CO2, and inevitably led to a further increase in CO2 in the atmosphere," said lead researcher Pierre Friedlingstein from the University of Exeter in the UK
"The atmospheric CO2 level, and consequently the world's climate, will only stabilise when global CO2 emissions are near zero," Friedlingstein noted.
