Detection of fossil-fuel CO2\xa0plummet in China due to COVID-19 by observation at Hateruma

Yasunori Tohjima,Prabir K Patra,Yosuke Niwa,Toshinobu Machida,Motoki Sasakawa,Hitoshi Mukai

doi:10.1038/s41598-020-75763-6

Abstract

The COVID-19 pandemic caused drastic reductions in carbon dioxide (CO2) emissions, but due to its large atmospheric reservoir and long lifetime, no detectable signal has been observed in the atmospheric CO2 growth rate. Using the variabilities in CO2 (ΔCO2) and methane (ΔCH4) observed at Hateruma Island, Japan during 1997–2020, we show a traceable CO2 emission reduction in China during February–March 2020. The monitoring station at Hateruma Island observes the outflow of Chinese emissions during winter and spring. A systematic increase in the ΔCO2/ΔCH4 ratio, governed by synoptic wind variability, well corroborated the increase in China’s fossil-fuel CO2 (FFCO2) emissions during 1997–2019. However, the ΔCO2/ΔCH4 ratios showed significant decreases of 29 ± 11 and 16 ± 11 mol mol−1 in February and March 2020, respectively, relative to the 2011–2019 average of 131 ± 11 mol mol−1. By projecting these observed ΔCO2/ΔCH4 ratios on transport model simulations, we estimated reductions of 32 ± 12% and 19 ± 15% in the FFCO2 emissions in China for February and March 2020, respectively, compared to the expected emissions. Our data are consistent with the abrupt decrease in the economic activity in February, a slight recovery in March, and return to normal in April, which was calculated based on the COVID-19 lockdowns and mobility restriction datasets.

Highlights

The outbreak of the new coronavirus (COVID-19) was first identified in Wuhan, China, in December 2019
As a result of these measures, it was estimated that the emissions of fossil-fuel-derived C O2 (FFCO2) in China decreased by about 25% during January–February[1,2]
We found that February 2020 was the only occasion when C O2 was systematically lower than the long-term (2011–2019) mean for 22 days out of the 29 days of the month, and 9 days in the 2020 values fell outside the 1-σ standard deviation range of the 2011–2019 average

Summary

Introduction

The outbreak of the new coronavirus (COVID-19) was first identified in Wuhan, China, in December 2019. This result validates convincingly the hypothesis that the ΔCO2/ΔCH4 ratio at HAT can track changes in FFCO2 emissions from China on a shorter time scale during the winter months when the terrestrial biosphere is in hibernation.

Results

Conclusion