Decrease in carbon dioxide emissions from fossil fuels due to COVID-19 detected by atmospheric observations

Atmospheric observations on the island of Hateruma, Japan, have successfully detected the decrease in CO2 from fossil fuels₂ emissions in China associated with the COVID-19 outbreak. The weather on Hateruma Island is often influenced by the northwest monsoon sweeping through China, which carries signals of air pollutants. The observed ratios of CO₂ and CH₄ the variability showed a significant decrease during February-March 2020, corresponding to a decrease of about 30% of China’s fossil fuel CO2₂ emissions, according to a simulation of the chemical-transport model.

Monitoring anthropogenic greenhouse gas emissions using atmospheric observations is a major challenge for decision making, like the Paris Agreement. Huge atmospheric observation networks consisting of a variety of platforms including satellites have been developed to monitor regional / national scale changes in anthropogenic greenhouse gas emissions. The outbreak of the novel coronavirus (COVID-19) impacted global socioeconomic activity, leading to a significant reduction in CO from fossil fuels₂ (FFCO)₂) and other anthropogenic air pollutants around the world. This situation gave us a unique opportunity to assess our ability to quantify changes in regional FFCO2 emissions using atmospheric observations. However, there are few observational evidence reports for CO₂ reduction of emissions due to the COVID-19 blockade, although a large number of publications have reported short-lived reductions in air pollutants from various parts of the world.

In Scientific reports from Nature Publishing, researchers from the National Institute for Environmental Studies (NIES), Japan, and the Japanese Agency for Marine-Terrestrial Science and Technology (JAMSTEC) analyzed atmospheric CO₂ and CH₄ concentrations observed at Hateruma Island, Japan, located in the continental margin of East Asia, and detected signals related to the FCO₂ reduction in China caused by the restrictions associated with the COVID-19 outbreak in the period January-March 2020.

We have estimated that FFCO2 emissions decreased by around 20% in the period January-February 2020 as a result of measures to prevent the spread of COVID-19 in China and the outside world. While a significant reduction in air pollutants has been reported, articles on atmospheric signals from the FCO₂ the reduction is yet to be found in the published literature. “The size of the atmospheric CO reservoir₂ is quite large and the atmospheric CO₂ has a relatively long shelf life. These characteristics determine the change in atmospheric CO₂ concentrations caused by the COVID-19 flu are rather small, “said Prabir K. Patra, study co-author and researcher at JAMSTEC.

To detect such weak signals in the CO₂ variations, the research team of NIES and JAMSTEC focused on the relative variation of atmospheric CO₂ and CH₄ observed on Hateruma Island for the past 20 years at daily time intervals. “The atmospheric observation at Hateruma Island is often affected by continental emissions during the winter due to the airflow pattern caused by the East Asian monsoon. We know that temporal variations in atmospheric CO₂ and CH₄ the concentrations show a remarkable similarity and temporal change in the CO ratio₂ to CH₄ the variations track the temporal change of fossil fuel emissions in China very well for the years before 2020, “said Yasunori Tohjima, lead author of the study and NIES researcher.” Thus the change ratio of CO₂ to CH₄ the signal reflecting the change in continental CO was expected to be detected₂ emissions related to COVID-19 restrictions. “

The research team found that the monthly average ratio of atmospheric CO2₂ to CH₄ the changes in January, February and March recorded the annual increase in FFCO2 emissions from China over the period 1997-2019. However, reports showed significant reductions in February and March 2020, which coincided with the lockdown period in China. “The relationship between the variation ratio and the FCO₂ emissions from China should be evaluated using an atmospheric transport model and a CO series₂ and CH₄ flow maps, “said Yosuke Niwa, co-author of the study and a researcher at NIES.” We used multiple atmospheric CO2 simulations₂ and CH₄ to Hateruma Island for various scenarios for reducing CO2 emissions from fossil fuels₂ using NICAM-TM. “The study therefore concluded that China’s FFCO₂ emissions decreased by about 30% in February and by about 20% in March 2020. “Our approach presented in this study has the potential to detect emission reduction signals from any specific region in near real time using continuous measurements and high-precision CO₂ and CH₄“, mentioned Prabir K. Patra.

Provided by the National Institute for Environmental Studies