In the US, emissions dropped by about a third for a couple of weeks in April, a development that Robert Jackson, a co-author of the study and a Guggenheim fellow at Stanford University, told Grist was "absolutely unprecedented".
The lockdown measures are expected to have a long-term effect that could lead to the biggest annual decrease in emissions since the end of World War II. However, they added, it is also likely to be temporary; with lockdown measures already being rescinded, daily global emissions are estimated to return close to 2019 levels by the end of the year, barely affecting the enormous amounts of carbon dioxide clouding our atmosphere and warming our planet more and more each year.
The research found that, on April 7, daily global carbon emissions dropped 17%.
As governments restricted travel to curb the spread of Covid-19, emissions from aviation were slashed by up to 75% and road transport halved in some countries. Washington state, for example, saw a more than 40 percent drop in emissions during its peak confinement, whereas the pandemic swallowed up just under 18 percent of Iowa's emissions during its peak.
The figure will be seven percent if the strictest lockdown rules remain all year long across much of the globe, and four percent if they are lifted soon. The team says a decrease in surface transport, such as auto travel, contributed 43 percent of this reduction, while declining emissions from industrial sources and power generation contributed another 43 percent. Despite everybody being confined to their homes, the increase of energy use from households has been modest and easily off-set by the gains from the other sectors.
Clear sky covers Iran's capital Tehran as air pollution levels drop due to the coronavirus outbreak
"With people being urged to stay home and isolate there was a corresponding increase in global residential emissions (2.8 per cent) which saw a 0.2 megatonne increase in Carbon dioxide at its peak decline". The measurements are from January through April of this year.
But getting the type of yearly cuts to reach that worldwide goal is unlikely, they said.
Additionally, the overall level of emissions reduction will be dependent on the degree to which activity returns back to "normal". Given the impact of the pandemic on the United States, Europe, China, and Russian Federation, some of the highest emitters of the greenhouse gas carbon dioxide, the level of CO2 fell dramatically over the last few months.
The impact of confinement on 2020 annual emissions is projected to be around 4% to 7% compared to 2019, depending on the duration of the lockdown and the extent of the recovery.
With lower emissions transport alternatives harder to come by, until such time as electric vehicle uptake grows, the changes to workplace arrangements forced by Covid-19 provide an opportunity to observe how emissions in the sector may be cut.