■ Greenhouse gas emissions plunge globally.

Peak daily reduction of 17% noted because of cuts in driving, flying, industry

The wave of lockdowns and shuttered economies caused by the coronavirus pandemic fueled a momentous decline in global greenhouse gas emissions, one unlikely to last, a group of scientists reported Tuesday.

As coronavirus infections surged in March and April, nations around the globe experienced an abrupt reduction in driving, flying and industrial output, leading to a startling decline of more than a billion tons of carbon dioxide emissions. That includes a peak decline in daily emissions of 17% in early April, according to the study published in the journal Nature Climate Change. For some nations, the drop was much steeper.

Scientists have long insisted that the world must drastically scale back carbon pollution — and quickly — to mitigate the worst effects of climate change over coming decades, though none have suggested that a deadly global pandemic is the way to accomplish it.

The study released Tuesday projects that total emissions for 2020 probably will fall between 4% and 7% compared with the prior year — an unheard-of drop in normal times, but considerably less dramatic than the decline during the first few months of the year, when economies screeched to a halt. The final 2020 figure will depend on how rapidly, or cautiously, people around the world resume ordinary life.

The unprecedented situation produced by the virus has offered a glimpse into the massive scale required to cut global emissions, year after year, in order to meet the most ambitious goals set by world leaders when they forged the 2015 Paris climate accord. Last fall, a United Nations report estimated that global greenhouse gas emissions must begin falling by 7.6% each year beginning in 2020 to avoid the worst effects of climate change.

Tuesday’s study underscores how far the world remains from that long-term aspiration. The forced plunge in greenhouse gas emissions in recent months, while extraordinary, returned carbon pollution levels to those last seen in 2006. And the recent changes probably will not last.

“History suggests this will be a blip,” said Rob Jackson, a Stanford University professor and one of the authors of the peer-reviewed study, which attempts to assess the virus’s impact by nation and economic sector. “The 2008 [financial] crisis decreased global emissions 1.5% for one year, and they shot back up 5% in 2010. It was like it never happened.”