As countries around the world implemented lockdown measures as part of their COVID-19 response, a measured decline in greenhouse gas emissions has emerged as a possible silver lining of the global pandemic.
But according to a study published in the journal Nature Climate Change on Friday, the effects on climate change will be negligible without aggressive investment in renewable energy and carbon-neutralizing technology.
The study, conducted by an international team led by researchers at University of Leeds, says that even if lockdown measures continue until the end of 2021—more than a year and a half in total—the planet may only cool by about 0.018 degrees Fahrenheit by 2030.
But if there is an aggressive investment in renewable energy sources after the pandemic, we could avoid an overall increase of 0.3 degrees by 2050. That might keep the planet within 1.5 degrees Celsius of warming from pre-industrial levels, in keeping with the Paris Climate Agreement, reports Matt Simon for Wired.
"Lockdown showed that we can change and change fast, but it also showed the limits of behavior change," Piers Forster, study co-author and director of the Priestley International Center for Climate at Britain's University of Leeds, tells AFP.
To understand how many kinds of greenhouse gases were emitted through travel, the researchers tracked Google’s and Apple’s anonymized mobility data from cell phones in 123 countries. They studied the changes in emission of ten greenhouse gases and air pollutants between February and June 2020. These traffic patterns suggest that the emission of gases like carbon dioxide and nitrogen oxides fell between 10 and 30 percent globally, according to a press statement.
However, it is challenging to know the exact amount of CO2 output in the atmosphere, because the gas persists for hundreds of years there. Any changes in emissions caused by the pandemic would be just a minor blip in the total quantity of CO2.
Ironically, a decline in factory production may actually cause increased warming. Particles like sulfur dioxide, which are emitted from coal mines, form aerosols that linger in the atmosphere and reflect some of the sun’s energy back into space. With a decrease in production, there are fewer aerosols added to the atmosphere by humans, and the Earth’s surface heats more easily.
“Really, the first effect of reducing emissions is in fact an increase, we think, in the surface temperature,” Piers Forster, director of the Priestley International Centre for Climate at the University of Leeds and a lead author on the new paper, tells Wired.
The research team ran models of different green stimulus packages. A moderate one, which allocates 0.8 percent of global GDP to low-carbon energy, would result in a global net-zero level of CO2 by 2060. But an aggressive package, which invests 1.2 percent, would bring the world to net-zero output a decade sooner.
"Our paper shows that the actual effect of lockdown on the climate is small. The important thing to recognize is that we've been given a massive opportunity to boost the economy by investing in green industries - and this can make a huge difference to our future climate," Harriet Forster, who co-authored the paper with her father, tells Matt McGrath for the BBC.
Investing in renewable energy sources can be coupled with sequestering technology to scrub carbon already in the air. Burying captured carbon underground is actually carbon negative, though the technology can be costly. Scientists are developing ways to recycle the captured carbon dioxide into new fuels for airplanes and container ships.
Though they are not yet falling, emissions may be slowing.
“It wouldn't take that much additional decarbonization to push it down, because there's this big disruption that we may not recover from for a few years,” Zeke Hausfather, a climate scientist and the director of climate and energy at the Breakthrough Institute, who wasn’t involved in this new research, tells Wired. “If we keep installing wind and solar panels and EVs and other decarbonization technologies at the rate we have over the last decade, we could end up seeing emissions peak this year.”
Still, Hausfather and other scientists are skeptical of the paper’s optimistic projection. Major emitters—namely China and the U.S.—have large numbers of coal mines and natural gas facilities that governments are likely going to be unwilling to shut down, according to Wired.
A return to pre-COVID emissions practices after the pandemic means "we will have thrown away our best chance of getting the world on track to net zero emissions,” Pete Smith, professor of soils and global change at the University of Aberdeen tells Patrick Galey of Phys.org.
"We have a small window of opportunity to get this right, and we can't afford to waste it," says Smith, who was not involved in the research.