The COVID-19 pandemic led governments around the globe to impose travel restrictions in an effort to reduce the spread of the disease. As a result, there was a significant reduction in traffic and economic activities all over the world. As urban areas account for most of the greenhouse gas (GHG) emissions, the Covid-19 lockdown had a significant effect on global emissions, offering a unique opportunity to evaluate the capabilities of GHG monitoring networks. A recent multi-institutional collaborative study, published in Environmental Research Communications and funded in part by the Climate Program Office’s Atmospheric Chemistry, Carbon Cycle and Climate (AC4) program, examined the sensitivity of observational systems to abrupt changes in emissions caused by the lockdown.
Researchers from multiple institutions from the US and abroad evaluated urban GHG measurement networks during the roughly 6-week COVID-19 lockdown in March 2020 using hourly GHG data from six North American cities (five in the US and one in Canada). The authors used various metrics to compare changes in CO2, CO, and CH4 during three periods in 2020 (pre-lockdown, lockdown, and ongoing recovery) relative to the previous years. The GHG networks demonstrated a significant decrease in CO2 and CO emissions during lockdown in all cities, while CH4 trends across cities were not statistically significant. The changes in CO2 and CO correlated with a decrease in traffic, but not with changes in meteorology and biology, suggesting that transportation-related emissions are responsible. The results demonstrate that these urban GHG monitoring networks are sensitive to rapid changes in emissions and are well suited for long-term monitoring of human impact on the atmosphere.
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