Scientists have previously found that, due to the shutdowns brought by COVID-19 last year, the atmospheric pollution has been improved as the pandemic largely restricts human activities. However, the secondary effects of the restrictions on the environment, including vegetation growth, have not been clarified.
According to the results of Prof. SU Fenzhen and his colleagues from the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, China experienced a brighter, greener, and earlier spring in 2020 than the previous years, which verifies that short-term changes in human activities can rapidly alter regional environments.
To investigate the effects of COVID-19 restrictions on environments such as atmosphere, radiation and vegetation in China, they analyzed remotely sensed data of the first 4 months of 2020 obtained from the earth observation satellites, to track the effects of China’s COVID-19 restrictions on human activity, atmosphere, radiation, and vegetation.
They used data from the Baidu migration platform to calculate the population movement intensity index, in which they provided a proxy for human activity. Changes in nitrogen dioxide and aerosol optical depth, and changes in leaf area index and gross primary productivity were used as a measure of variations in air quality and vegetation (the greenness of a region), respectively.
Next, the team analyzed the indices for spring months in the years 2015 to 2020. They found that travel decreased by 58% in the first 18 days after COVID-19-related restrictions in China. Then the optical clarity of the atmosphere improved and more radiation reached the vegetation canopy. As a result, the spring of 2020 arrived 8 days earlier and vegetation was 17.45% greener.
The study was in collaboration with the University of Cape Town, the University of Tasmania and the University of Southern California, which is supported by the Chinese Academy of Sciences and the National Natural Science Foundation of China.
F. Su, D. Fu, F. Yan, H. Xiao, T. Pan, Y. Xiao, L. Kang, C. Zhou, M. Meadows, V. Lyne, J. P. Wilson, N. Zhao, X. Yang, G. Liu, Rapid greening response of China’s 2020 spring vegetation to COVID-19 restrictions: Implications for climate change. Science Advances 7, (2021) DOI: 10.1126/sciadv.abe8044.