What are different measures of mobility changes telling us about emissions during the COVID-19 pandemic?

Abstract

Recent work used novel mobility data for assessing the impact of the COVID-19 pandemic on traffic CO 2 emissions. However, we observe errors in excess of 60%.• The relationship between mobility and traffic activity data could not be explained by a general relationship over all investigated regions.• Errors in emission estimates come from the scaling with non-fuel activity data and the usage of mobility data as a proxy for traffic.

Tropospheric NO2 and O3 Response to COVID‐19 Lockdown Restrictions at the National and Urban Scales in Germany

“…These actions include physical distancing, a ban on large group gatherings, home office work, and international and domestic travel restrictions (DW COVID‐19, 2020). These measures resulted in a significant reduction in emissions following economic activity and overall mobility (Evangeliou et al., 2021; Gensheimer et al., 2021; Guevara et al., 2021; Le Quéré et al., 2020; Z. Liu, Ciais, et al., 2020; Z. Liu, Deng, et al., 2020; Turner et al., 2020). There has been a lot of interest in studying this time window and its impacts on the Earth system.…”

Short run “rebound effect” of COVID on the transport carbon footprint

“…For instance, unlike in the capital city of Santiago, there is no real time traffic data collection of the public transport in the cities under study (Ministry of Transport – https://datos.gob.cl/organization/subsecretaria_de_transporte ). Various studies confirm that incorporating information on traffic congestion levels significantly increases emissions per kilometer traveled ( Du et al, 2021 ; Gensheimer et al, 2021 ; Velasco, 2021 ). It is therefore important to note that we systematically underestimate the real drop in CO 2 emissions.…”

“… Grivas et al (2020) , Lamprecht et al (2021) , Venturi et al (2021) , and Turner et al (2020) estimated reductions of 58 %, 38 %, between 37 % and 43 % and 48 % respectively, while Yadav et al (2021) detected drops of more than 30 %. The estimated drop in emissions strictly associated with mobility offers values between 7 and 12 % ( Gensheimer et al (2021) , 41 % ( Velasco, 2021 ), reaching nearly 90 % during the week in which a higher level of confinement is applied. Of course, the number of trips has been reduced (with an increase in telecommuting), but, and perhaps less obviously, car use has increased.…”

“…The methodologies used to estimate the reduction in CO 2 levels associated with mobility in times of confinement can be divided into two categories. The first uses local data on mobility, traffic, and congestion to estimate CO 2 emissions ( Du et al, 2021 ; Gensheimer et al, 2021 ; Velasco, 2021 ). The second method uses in situ gas concentration data ( Lamprecht et al, 2021 ; Nicolini et al, 2022 ; Grivas et al, 2020 ; Venturi et al, 2021 ; Turner et al, 2020 ; Yadav et al, 2021 ).…”

Dramatic Lockdown Fossil Fuel CO2 Decrease Detected by Citizen Science-Supported Atmospheric Radiocarbon Observations

“…The slightly larger reduction in traffic implied by the Apple Mobility Data than in our CO 2ff observations could be because changes in driving requests are not an exact proxy for emission changes. 29 Waka Kotahi New Zealand Transport Agency traffic count data shows a decrease in traffic counts during Level 4 relative to Level 1 of −75% in Auckland (two locations), −79% in Wellington, −74% in Christchurch, and −71% in Hamilton (https://opendata-nzta.opendata.arcgis.com/search?q=traffic). No traffic count data was available for Gisborne.…”