Coronavirus lockdowns in 2020 have helped the world cut its carbon dioxide emissions by 7%, the biggest drop ever, new preliminary figures show.

The Global Carbon Project, an authoritative group of dozens of international scientists who track emissions, calculated that the world will have put 37 billion US tons (34 billion metric tons) of carbon dioxide in the air in 2020. That’s down from 40.1 billion US tons (36.4 billion metric tons) in 2019, according to a study published in the journal Earth System Science Data.

Fossil CO2 emissions have fallen in all the world’s biggest emitters, the study estimates – including by 12% in the US, 11% in the EU, 9% in India and 1.7% in China.

Researchers say the emissions are down mainly because more people stayed home and traveled less by car or plane this year.

Transport accounted for the largest share of the global decrease in emission of carbon dioxide, the chief man-made greenhouse gas.

Emissions from road transport fell by roughly half in April when the first wave of the coronavirus was at its peak. By December, it had fallen 10% year-on-year.

Emissions from aviation were down by 40% this year. Industrial activity, which accounted for 22% of the global total, was down by 30% in some countries due to strict lockdown measures.

“Of course, lockdown is absolutely not the way to tackle climate change”, said study co-author Corinne LeQuere, a climate scientist at the University of East Anglia.

She added, “All elements are not yet in place for sustained decreases in global emissions, and emissions are slowly edging back to 2019 levels.”