Temporary decline in atmospheric carbon dioxide in Detroit, MI due to the Covid-19 pandemic
Reduced human activity associated with lockdown protocols due to the Covid-19 pandemic have temporarily changed carbon emission patterns of urban ecosystems globally. Understanding how these changes anthropogenic activities contribute to the urban emissions offer the opportunity to better understand the carbon dynamics outside pandemic conditions. Here we explore how the adjusted social behaviors impact atmospheric carbon dioxide (CO2) in Detroit, MI where the substantial emissions are generated by industrial facilities as well as domestic energy and other anthropogenic uses. Atmospheric CO2 concentration and net ecosystem exchange (NEE) were measured by a typical eddy covariance system situated on the Wayne State University campus near downtown Detroit. We present approximately five months of data that include pre-pandemic 鈥渘ormal鈥 conditions (January 13, 2020-March 6, 2020), pandemic 鈥渟helter-in-place鈥 conditions (March 24, 2020-May 28, 2020), and pandemic 鈥渞estart鈥 conditions (June 1, 2020-present as of July 29, 2020). Results demonstrate that substantial reduction in road traffic and domestic energy use during the lockdown resulted in significantly decreased daily CO2 concentration and NEE from 431.0 ppm and 51.1 gCO2 m-2 under regular socio-economic conditions to 427.5 ppm and 12.9 gCO2 m-2, respectively. Similar diel patterns in with less variation by day of week suggest that the non-point road traffic (up to 50-70% of reduction in volume) and domestic heating still dominated the urban CO2 concentration under lockdown where considerable offset was found by the urban vegetation patches at the last month of the study period. However, emissions from the industrial facilities clustered southwest from the observation tower affected the city area with overwhelmingly elevated NEE. While aftermath of the Covid-19 crisis will need the structural reform in the socio-economic recovery, we suggest that the sustainable transition might be a best strategy for the shrinking cities to mitigate the impact and potential rebounds in both economy and carbon emissions.