The current pandemic is an unprecedented opportunity to study how global climate responds to a massive drop in human activity. And so far, it appears that lockdowns are likely to have little effect on climate change unless future economic recovery plans include green policies, according to a study published Thursday (August 6) in Nature Climate Change.
While previous research this spring had noted a 17 percent decline in carbon dioxide emissions worldwide associated with reduced human activity during the pandemic, the current study includes nine other greenhouse gases and relies on anonymized movement data gleaned from Google and Apple phones to track the activity of 4 billion people. In April 2020, the authors found, global emissions fell 10 percent to 30 percent as the world sheltered in place and businesses operated at a reduced capacity. The researchers caution that despite these sizable declines, the overall effect on climate may only amount to a decrease in the global temperature of 0.01 °C over the next five years.
“The fall in emissions we experienced during COVID-19 is temporary, and therefore it will do nothing to slow down climate change,” Corinne Le Quéré, a climate scientist at the University of East Anglia and a coauthor on the new study, tells Science News. She notes that the response of global leaders in this moment could be “a turning point if they focus on a green recovery, helping to avoid severe impacts from climate change.”
The results are the brainchild of a father-daughter pair who found themselves with time on their hands after daughter Harriet Forster’s exams at Queen Margaret’s School were canceled. She decided to help her father Piers, a climate scientist at the University of Leeds, scrape and collate data on air quality and mobility to better understand how the emissions of 10 different greenhouse gases are changing during the pandemic. Mobility data can be linked to energy-consuming activities such as driving, working, and shopping that generate emissions.
Jenny Stavrakou, a climate scientist at the Royal Belgian Institute for Space Aeronomy who was not involved in the study, tells Science News that the use of mobility data from cell phones is “an innovative approach” for estimating short-term changes. Many, although not all, greenhouse gases sit in the atmosphere for a long time, making it difficult to track smaller changes over days or months. “Mobility data have big advantages,” Stavrakou adds, because they are constantly updated and can be used to infer trends in gas emissions over much smaller timescales.
The Forsters and their colleagues pulled together many different datasets, including the previous research tracking carbon dioxide, and their study ultimately included information from 123 countries collected between February and June of 2020. In addition to the mobility data, they used air-quality monitoring stations from around the world to focus on shorter-lived greenhouse gases, Grist reports. Nitrogen dioxide, for example, is a useful proxy for quantifying carbon dioxide, as the two are released together during the burning of fossil fuels, but nitrogen dioxide dissipates much more quickly and is easier to assess trends over the last few months of the pandemic.
While global emissions fell between 10 percent and 30 percent on average, the team found that the benefits were largely mitigated by the interplay between different gases. For example, carbon dioxide and nitrogen oxides fell by roughly 30 percent, a finding the authors attributed to less driving and use of public transportation. But at the same time, sulfur dioxides released by industry fell by 20 percent. While the former two gases increase global temperatures, sulfur dioxide actually cools the earth by forming aerosols that reflect incoming sunlight.
Together, their findings suggest that the drop in emissions will be negligible in the long term. Peter Neff, a climate scientist at the University of Minnesota, tells Grist in an email these results show that “to have a good chance of limiting global warming to the Paris Agreement target of 1.5 °C by 2050, we essentially need reduction in carbon emissions similar to that caused by the initial pandemic response every single year for the next decade and beyond.”
Some of the more positive climate aspects during the pandemic could be incorporated into policy moving forward, BBC News reports. For example, road traffic is still down in many places, and a shift towards greener transportation options could keep emissions lowered, as could the decision to retain some level of telework in the future. Stimulus money could be funneled into emerging renewable technologies and electric cars. The authors stress that if the world returns to its previous energy consumption behaviors, the odds of meeting the Paris Agreement threshold are very low.
Nevertheless, Pier Forster is optimistic that the challenge can be met. “Disasters are often historically the time of biggest change,” he tells BBC News. “For once, government, industry and public voices are all pretty aligned that green jobs and green investments are the way to build back better. We just need to do it.”