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Words by Marissa Lo
7 September 2022

During the lockdown in May 2020, the typically busy Regent Street in Central London, UK, was deserted (Credit: Kwh1050, CC BY-SA 4.0, via Wikimedia Commons).

The COVID-19 pandemic and resulting lockdowns caused everyday activities to grind to a halt. Across the globe, non-essential travel and businesses were restricted. The resulting decline in air pollution and CO2 emissions was noticeable, with news outlets publishing stark images that showed the impact of lockdowns on air quality, particularly in cities. 

Ordinarily, CO2 emissions from anthropogenic activity vary due to numerous interconnected factors, such as season, weather, and time of day. Zhu Liu at Tsinghua University, China, and collaborators from 19 other institutions, focussed on quantifying the variability in CO2 emissions resulting from lockdown restrictions in 2020. Using inventories and daily near-real-time data from Carbon Monitor – a tool that combines different data sets to produce a publicly available, living dataset – the team show that the dramatic decrease in global activity resulting from the COVID-19 lockdown restrictions led to a 6.3% reduction in CO2 emissions (equivalent to 2,232 megatonnes of CO2) in 2020 compared with 2019. Daily CO2 emissions were divided by sector into power generation, industry, ground transportation, aviation, and maritime transportation, with the results showing that the sharp decline in ground transportation had the most significant impact on CO2 emissions – these were down 10.9% (equivalent to 709 megatonnes of CO2) in 2020 compared to 2019. 

The results have important implications for future climate change mitigation. Liu and colleagues show that the temporary reduction in CO2 emissions observed in 2020 are on par with those needed in the long term to limit global warming to 1.5 °C. Considering the scale at which the pandemic and lockdown restrictions affected every country across the globe, to achieve this will require significant restructuring of key sectors, such as energy and transport. Finally, while highlighting the importance of transitioning from fossil fuel-based to renewable energy sources, the authors acknowledge the need to balance economic recovery with a green recovery.

Marissa Lo

DETAILS: Nat. Geosci., 15, 615–620 (2022); https://doi.org/10.1038/s41561-022-00965-8  

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