The Covid-19 lockdown and drop in transport use caused fossil carbon dioxide emissions to drop at record levels, research has found, although those in the atmosphere continue to rise.
Even as lockdowns were eased around the globe, continued movement restrictions mean emissions from road transport fell by 10 per cent compared to 2019 and 40 per cent in air travel.
At one point during the height of the pandemic, releases from surface transport plummeted by half.
Overall, there was a fall of about 2.4 tonnes in fossil carbon dioxide emissions in 2020, experts at the Global Carbon Project, the University of East Anglia and the University of Exeter said.
But it is unclear how much of a long-term effect there will be, especially as governments take action to restart their ailing economies, meaning emissions could well return to previous levels.
All elements are not yet in place for sustained decreases in global emissions and they are slowly edging back to 2019 levels.
"Government action to stimulate the economy at the end of the Covid-19 pandemic can also help lower emissions and tackle climate change,” said Prof Corinne Le Quere of the University of East Anglia's school of environmental sciences.
"Incentives that help accelerate the deployment of electric cars and renewable energy, and support walking and cycling in cities are particularly timely given the extensive disturbance observed in the transport sector this year."
The effects on emissions was particularly obvious in countries such as the US and EU member states, where action is already under way to limit coal use.
But it is possible that carbon releases, which fell by as much as a third in the spring, are already returning to levels seen in 2019.
"Although global emissions were not as high as last year, they still amounted to about 39 billion tonnes of carbon dioxide and inevitably led to a further increase in carbon dioxide in the atmosphere,” said lead researcher Prof Pierre Friedlingstein, of the University of Exeter,
The atmospheric carbon dioxide level, and consequently the world's climate, will only stabilise when global carbon dioxide emissions are near zero."