17 December 2020

Scientific American: “Global CO2 Emissions saw Record Drop during Pandemic Lockdown”

On that day, almost 90% of global CO2 was released in areas under lockdown to avoid spreading the virus. A study published yesterday in Nature Climate Change estimates emissions on April 7 fell by 17%, more than any other day during the first four months of 2020.

At first glance, a reduction of that magnitude appears massive. In comparison, global emissions dropped 1.5% during the Great Recession in 2009.

But a deeper look shows that individual changes in behavior produce limited emission reductions. Much of the world stopped traveling, eating in restaurants and buying merchandise. It was an unmatched experiment and yet 80% of emissions were untouched.


Scientists have sought to reject claims that emissions reductions associated with the coronavirus are a silver lining. Carbon dioxide is a long-lived gas capable of staying in the atmosphere for up to a century, meaning a temporary drop in emissions is unlikely to change the world’s climate trajectory.

The magnitude of reductions has to be similar, but it has to persist over time, and it can’t be as disruptive as this has been, said Steven Davis, an earth scientist at the University of California, Irvine, who did not participate in the study.

Benjamin Storrow

Back in spring when the pandemic started, my personal conspiracy theory about the emergence of the virus was the following: dismayed by the lack of action against global warming, a couple of climate scientists decided to take the matter into their own hands. Together with a group of virologists, they designed a virus (infectious enough to spread widely, with a long incubation period to escape quick detection, and relatively low mortality to minimize casualties) to scare the population into consuming and traveling less, forcing them to adopt a less carbon-intensive lifestyle.

Weekly carbon dioxide concentrations before and during California lockdown
Weekly carbon dioxide concentrations during the six weeks before shelter-in-place (Feb. 2-Mar. 14, purple) and six weeks during shelter-in-place (Mar. 22-May 2, green). The solid lines show the median CO2 levels across the BEACO2N network. (UC Berkeley graphic by Ronald Cohen)

Naturally, reality is too complex to be explained with simplistic solutions such as this. The theory that the virus is artificial has been debunked long ago, and, as this article and other studies have shown, temporary emissions reductions, however large, have an insignificant impact on global warming because of the amount of CO2 already accumulated in the atmosphere. Already, after the lockdown lifted, greenhouse gas emissions have quickly climbed back up, nearing 2019 levels. The only sustainable solution are structural changes, primarily in energy generation and transportation.

Nevertheless, the lockdowns have provided an unexpected opportunity to conduct scientific studies about the impact of aerosols and telecommuting, which could later lead to better climate forecasting and policies. I am not particularly optimistic that we will manage to radically change the global economy fast enough, but maybe some of us will remember the clearer skies of the lockdown and try to make them the norm rather than the exception.

Global daily CO2 emissions for sectors
Daily CO2 emissions by sectors in 2019 and January 1st through July 1st 2020 for a power sector and b industry sector, and January 1st through August 1st 2020 for c ground transportation sector, d residential sector, and aviation sector (e domestic aviation; f international aviation). Liu, Z., Ciais, P., Deng, Z. et al. Near-real-time monitoring of global CO2 emissions reveals the effects of the COVID-19 pandemic. Nat Commun 11, 5172 (2020)

Post a Comment