“What makes our study unique is the analysis of meticulously collected near-real-time data,” explains lead author Zhu Liu from the Department of Earth System Science at Tsinghua University in Beijing. “By looking at the daily figures compiled by the Carbon Monitor research initiative we were able to get a much faster and more accurate overview, including timelines that show how emissions decreases have corresponded to lockdown measures in each country. In April, at the height of the first wave of Corona infections, when most of the major countries shut down their public life and parts of their economy, emissions even declined by 16.9 %. Overall, the various outbreaks resulted in emission drops that we normally see only on a short-term basis on holidays such as Christmas or the Chinese Spring Festival.”
The study, published in the issue of Nature Communications, shows which parts of the global economy were most impacted. “The greatest reduction of emissions was observed in the ground transportation sector,” explains Daniel Kammen, professor and chair of the Energy and Resources Group and also a professor in the Goldman School of Public Policy, University of California, Berkeley. “Largely because of working from home restrictions, transport CO2 emissions decreased by 40 % worldwide. In contrast, the power and industry sectors contributed less to the decline, with -22 % and -17 %, respectively, as did the aviation and shipping sectors. Surprisingly, even the residential sector saw a small emissions drop of 3 %: largely because of an abnormally warm winter in the northern hemisphere, heating energy consumption decreased with most people staying at home all day during lockdown periods.”
The researchers based their estimates on a broad range of data to paint this detailed and multidimensional picture: reliable, hourly electricity generation datasets in 31 countries, regular vehicle traffic in more than 400 cities worldwide, daily Global passenger flights, monthly industry output data in 62 countries, as well as fuel consumption data for building emissions in more than 400 cities worldwide.
Strong rebound effects were also noticed by the researchers. Except for the continuing decrease in emissions from the transport sector, most economies have resumed their normal rate of CO2 emissions by July 2020, once lockdown measures have been lifted. But this would have a very minute impact on the long-term concentration of CO2 in the atmosphere even though they stayed at their historically low levels.
Thus, the authors stress that the only valid strategy to stabilize the climate is a complete overhaul of the industry and commerce sector. “While the CO2 drop is unprecedented, decreases of human activities cannot be the answer,” says Co-Author Hans Joachim Schellnhuber, founding director of the Potsdam Institute for Climate Impact Research. “Instead, we need structural and transformational changes in our energy production and consumption systems. Individual behaviour is certainly important, but what we need to focus on is reducing the carbon intensity of our global economy.”
By Jumana Jabeer.