The sweeping halt of economic activity around the world has governments scrambling to provide adequate relief for vulnerable industries and people. 

But one silver lining is emerging from this economic freeze: carbon emissions are down. And scientists estimate that they could fall even farther, specifically to pre-World War II levels.

“I wouldn’t be shocked to see a 5 percent or more drop in carbon dioxide emissions this year, something not seen since the end of World War Two,” Rob Jackson, a professor of Earth system science at Stanford University in California, told Reuters. 

This conclusion is based on data collected by the Global Carbon Project, of which Jackson is the chair. 

The research group published “widely watched” annual emissions figures, Reuters reports. With Americans working from home and industries slashing production, scientists at the Global Carbon Project estimate that carbon output could see decreases of 5 percent or more on a year-on-year basis.

Experts have called for dramatic action to reduce climate change, with the Intergovernmental Panel on Climate Change (IPCC) warning of the catastrophic dangers to global health and called for a limit of a 1.5 degree Celsius rise in temperatures.

Satellite images captured the reduction in pollution over mainland China as industries shuttered to control the coronavirus spread.

But, this silver lining may be short lived. With no permanent structural change in place for when the stay-at-home mandates end, the world is likely to return to producing its previous carbon emission levels.

“This drop is not due to structural changes so as soon as confinement ends, I expect the emissions will go back close to where they were,” Corinne Le Quéré, a climate scientist at the University of East Anglia in eastern England, told Reuters.

Jackson corroborated Le Quéré’s theory, stating that during the 2008 financial crisis and recession, economic activity came to a similar standstill, causing carbon emissions to fall as the economy contracted.

As the economy steadily rebounded, emissions increased by a cumulative 5.1 percent, according to Jackson.

According to 2018 data from the Global Carbon Atlas, the U.S., which relies heavily on fossil fuels to keep the economy running, was the second largest carbon producer in the world.

Pierre Friedlingstein, the chair of mathematical modeling of the climate system at the University of Exeter, told Reuters that he isn’t optimistic about the impact the COVID-19 crisis could have on global carbon emissions if leading economies simply return to normal greenhouse gas levels.

“Even if there is a decline in emissions in 2020, let’s say 10 percent or 20 percent, it’s not negligible, it’s important. But from a climate point of view, it would be a small dent if emissions go back to pre-COVID-19 crisis levels in 2021,” Friedlingstein said. 

The best way to see if structural change is on the horizon is to look at the stimulus packages multiple governments are ratifying, and gauge the impact on carbon emissions, Reuters reports.

Recently, the Trump administration announced the rollback of the Obama-era Clean Car Standards that regulated carbon emissions, and the Chinese government is reportedly exploring ways to help the ailing auto industry by relaxing emissions standards. 

These examples of returning to the same emissions practices could greatly undermine any progress inadvertently achieved by the coronavirus pandemic.

“This is why it is important to think about the nature of the economic stimulus packages around the world as countries come out of the most immediate health crisis,” Dan Lashof, U.S. director at the World Resources Institute, explained to Reuters.