Strict government policies have been put in place to limit the spread of COVID-19. In many nations, population confinement has been used as one such measure, resulting in drastically modified energy use owing to, for example, shifts in transportation patterns or industrial operations. Anthropogenic CO2 emissions can therefore also be expected to have changed during the pandemic.

Corinne Le Quéré from the University of East Anglia, UK, and co-authors, use a combination of energy, activity and policy data to estimate the changes in daily CO2 emissions arising from COVID-19-related confinement impacts on six economic sectors: power, surface transport, industry, aviation, residential buildings, and public buildings and commerce. Compared with 2019, global daily emissions in early April decreased by 17% (depending on assumptions, 11% to 25%), reflecting a reduction of 17 Mt CO2 per day (11–25 Mt CO2 per day), nearly half of which (43%, or 5.9–9.6 Mt CO2 per day) can be attributed to changes in the surface transport sector. The largest relative declines, however, were observed in the aviation industry sector (60%, or 1.3–2.2 Mt CO2 per day). Up until the end of April 2020, these changes reflect total global decreases of 1,048 Mt CO2 (543–1,638), which, depending on when lockdown measures ease, could reach 2,729 Mt CO2 (986–4,717).

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While these CO2 reductions represent environmental benefits, the total ‘savings’ are consistent with those needed year-on-year to reach the goals of the Paris Agreement. Thus, the extreme measures during the COVID-19 pandemic also act to highlight the fundamental changes needed to constrain impacts from anthropogenic climate change. Moreover, post-crisis rebounds in emissions may counter or restore emissions along original trajectories, demonstrating the influence of political and economic stimuli in dictating emissions trajectories well beyond 2020.