Coronavirus restrictions led to a record 7% fall in global carbon emissions last year, but the drop will be short-lived unless efforts to phase out fossil fuel are intensified, a study by scientists in the journal Nature Climate Change said.
The study by scientists from institutions in Australia, Britain, France, Norway and the United States, confirmed preliminary estimates from May last year that global CO2 emissions from fossil fuels fell by 7%, or 2.6 billion tonnes, to 34 billion tonnes.
On Tuesday, the International Energy Agency said global CO2 emissions dropped by 5.8% in 2020.
The study in Nature Climate Change analysed daily CO2 emissions across 71 countries and six economic sectors, using data from daily electricity use and mobility tracking services.
To keep the global temperature rise to 1.5-2 degrees Celsius (2.7 degrees Fahrenheit) this century, emissions must decrease by 1-2 billion tonnes a year, the United Nations says.
"When fossil fuel infrastructure is put into use again, there is a risk of a big rebound in emissions in 2021 as was seen in the wake of the global financial crisis in 2009," said Glen Peters, research director at Norwegian climate research institution CICERO, which took part in the study.
Although a full rebound is unlikely this year as the pandemic continues, future emissions will largely depend on the alignment of countries' economic recovery plans with climate targets and green growth, the research said.
To meet climate targets under the 2015 Paris climate accord, post-Covid-19 actions must deliver a ten-fold increase in emissions cuts compared with the period 2016-2019, together with divestment from fossil fuel infrastructure worldwide.
Commenting on the paper, Robin Lamboll, research associate in climate science and policy at London's Grantham Institute said: "A drop in emissions for one or two years doesn't really have a long-term effect on climate change."
"The question for the future is to what extent the emissions reduction indicates a change of culture, and to what extent government assistance is going towards growing a greener economy rather than rebooting fossil fuels," he added.