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. 2021 Oct 27;193(11):751.
doi: 10.1007/s10661-021-09541-w.

No evidence for global decrease in CO2 concentration during the first wave of COVID-19 pandemic

YoungSeok Hwang  1 , Jong Wook Roh  1   2 , Dongjun Suh  1   3 , Marc-Oliver Otto  4 , Stephan Schlueter  4 , Tanupriya Choudhury  5 , Jeung-Soo Huh  1   3 , Jung-Sup Um  6   7
Affiliations

No evidence for global decrease in CO2 concentration during the first wave of COVID-19 pandemic

YoungSeok Hwang et al. Environ Monit Assess. .

Abstract

Numerous studies have reported that CO2 emissions have decreased because of global lockdown during the first wave of the COVID-19 pandemic. However, previous estimates of the global CO2 concentration before and after the outbreak of the COVID-19 pandemic are limited because they are based on energy consumption statistics or local specific in-situ observations. The aim of the study was to explore objective evidence for various previous studies that have claimed the global CO2 concentration decreased during the first wave of the COVID-19 pandemic. There are two ways to measure the global CO2 concentration: from the top-down using satellites and the bottom-up using ground stations. We implemented the time-series analysis by comparing the before and after the inflection point (first wave of COVID-19) with the long-term CO2 concentration data obtained from World Meteorological Organization Global Atmosphere Watch (WMO GAW) and Greenhouse Gases Observing Satellite (GOSAT). Measurements from the GOSAT and GAW global monitoring stations show that the CO2 concentrations in Europe, China, and the USA have continuously risen in March and April 2020 compared with the same months in 2019. These data confirm that the global lockdown during the first wave of the COVID-19 pandemic did not change the vertical CO2 profile at the global level from the ground surface to the upper layer of the atmosphere. The results of this study provide an important foundation for the international community to explore policy directions to mitigate climate change in the upcoming post-COVID-19 period.

Keywords: COVID-19; Carbon budget; CO2 profile; Corona; GOSAT (Greenhouse Gases Observing Satellite); Global Atmosphere Watch (GAW); World Meteorological Organization (WMO).

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Flowchart for the data analysis procedures
Fig. 2
Fig. 2
Six WMO/GAW stations deployed across latitudinal bands from the Arctic to the Mediterranean Sea. ZEP Zeppelin mountain (Norway), BIR Birkenes Atmospheric Observatory (Norway), TOH Torfhaus (Germany), SSL Schauinslan (Germany), IPR Ispra (Italy), CMN Monte Cimone (Italy)
Fig. 3
Fig. 3
GOSAT XCO2 concentrations before and after the COVID-19 outbreak (unit: ppm): a March–April 2020; b March–April 2019
Fig. 4
Fig. 4
Annual variations of GOSAT XCO2 concentrations worldwide before and after COVID-19 outbreak (unit: ppm). *Number of observation points. †Obtained by subtracting the data from those of the same month in 2019 from the GOSAT/MLO measurements of March–April 2020 in the yearly CO2 data. **p < 0.001; unpaired t test. The names of the top 20 countries in terms of confirmed COVID-19 patients as of 30 April 2020 are marked on the map, excluding Belgium, the Netherlands, Portugal and Switzerland due to visibility constraints. MLO Mauna Loa Baseline Atmospheric Observatory, SD standard deviation
Fig. 5
Fig. 5
Annual variations of GOSAT XCO2 concentrations worldwide before and after the COVID-19 outbreak (unit: ppm): a worldwide including ocean; b worldwide land; c Europe; d USA; e China (*p < 0.001; unpaired t test)
Fig. 6
Fig. 6
Annual variations of CO2 concentrations measured at the WMO/GAW stations before and after the COVID-19 outbreak (unit: ppm): Zeppelin mountain (ZEP), Norway; Torfhaus (TOH), Germany; Monte Cimone (CMN), Italy; Ispra (IPR), Italy; and Birkenes Atmospheric Observatory (BIR), Norway (*p < 0.001; unpaired t test)
Fig. 7
Fig. 7
Global mean (unit: ppm) of GOSAT XCO2 and CO2 concentrations measured at WMO/GAW stations located in the USA and Europe since 1958, including the COVID-19 pandemic period (unit: ppm). a Global mean (unit: ppm) of GOSAT XCO2 and CO2 concentrations measured at WMO/GAW stations before and after COVID-19 pandemic period. This is a magnified portion from Fig. 6b*. b Global mean (unit: ppm) of GOSAT XCO2 and CO2 concentrations measured at WMO/GAW stations since 1958. This trend indicates that CO2 concentrations keep accelerating since 1958, even after the COVID-19 pandemic period. MLO Mauna Loa Baseline Atmospheric Observatory (USA), SSL Schauinslan (Germany), CMN Monte Cimone (Italy), ZEP Zeppelin mountain (Norway)
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