Integrated Carbon Observation System, ICOS, is the first to release results of a scientific study that shows a large reduction in carbon dioxide (CO2) emissions in seven European cities during the lockdown caused by the Covid-19 virus. The study is conducted by ICOS ecosystem scientists together with colleagues around Europe.The Covid-19 related restrictions have forced many of us to stay at home. This has strongly reduced road traffic and economic activities particularly in cities and urban areas where majority of the people live. Consequently, this has also cut down human-induced carbon dioxide (CO2) emissions to the atmosphere. Although this reduction is not strong enough to be globally visible in the atmosphere (e.g. see ICOS news), at local scale the changes in emissions can be observed.