Direct observations of CO2 emission reductions due to COVID-19 lockdown across European urban districts

The measures taken to contain the spread of COVID-19 in 2020 included restrictions of people's mobility and reductions in economic activities. These drastic changes in daily life, enforced through national lockdowns, led to abrupt reductions of anthropogenic CO2 emissions in urbanized areas all over the world. To examine the effect of social restrictions on local emissions of CO2, we analysed district level CO2 fluxes measured by the eddy-covariance technique from 13 stations in 11 European cities. The data span several years before the pandemic until October 2020 (six months after the pandemic began in Europe). All sites showed a reduction in CO2 emissions during the national lockdowns. The magnitude of these reductions varies in time and space, from city to city as well as between different areas of the same city. We found that, during the first lockdowns, urban CO2 emissions were cut with respect to the same period in previous years by 5% to 87% across the analysed districts, mainly as a result of limitations on mobility. However, as the restrictions were lifted in the following months, emissions quickly rebounded to their pre-COVID levels in the majority of sites. [Display omitted] •Following the outbreak of the COVID-19 pandemic in 2020, people's activities drastically changed due to mobility restrictions.•This affected urban CO2 emissions and we wanted to quantify its impact during the lockdown and in the following months.•We analysed eddy covariance measurements of urban CO2 fluxes over the lockdown in thirteen European city districts.•Data provided the measured evidence of a consistent reduction of CO2 emissions, proportional to the stringency of restrictions.•The reduction was temporary in most of the city districts, as emissions rebounded to usual levels once restrictions were eased.