Professor Piers Forster, director of the Priestley International Centre for Climate at the University of Leeds, started working on the analysis with his daughter Harriet after her A-levels were cancelled this year.
They used mobility data from Google and Apple to calculate how different greenhouse gases and pollutants changed between February and June in 123 countries - a wider team later assisted with detailed analysis.
Overall, global NOx emissions declined by as much as 30% in April, contributing to a short-term cooling since the start of the year.
People around the world reduced their travel significantly during April 2020 - leading to around 80% of the population in114 countries (4 billion people) to reduce their travel by more than 50%.
Plus, the data suggests that the decline in surface-transport emissions led the global CO2 and NOx emissions to decrease by as much as 30% in April 2020.
For the residential sector, the study looked at smart meter analysis from Octopus Energy - discovering that many households were already occupied during the day, before lockdown restrictions were imposed. When additional occupants were added, energy use only increased by 4%.
There's no denying that these are positive takeaways from a catastrophic pandemic - but the environmental success has been short-lived. We have now come crashing back down to the reality of climate change, as the study explains emission levels are already returning to near-normal in parts of Asia.
The study estimates that the direct effect of the pandemic-driven response will be negligible, with a cooling of around 0.01 - 0.005 °C by 2030.
