Impacts of the Novel Corona virus shutdowns on CO2 emissions, concentrations and distribution.

Abstract:

Changes to activity, energy use and energy production resulted in widely-reported changes to fossil fuel use, and CO₂ emissions. We analyzed the effects of COVID activity changes on the global carbon cycle. The emissions were tracked in detail using information about aviation, mobility, and power consumption, and demonstrate significant reductions relative to expected emissions and prior years. Using an atmospheric transport model, we simulated the local and far-field impacts of reduced emissions. Results include simulated CO₂ fields, as well as the simulated seasonal cycle at Mauna Loa and both provide an early view of documented emission change, and guidance for analysis of data as it becomes available. Local boundary layer concentrations were significantly reduced, but far-field (downwind) concentration reductions, relative to baselines with business-as-usual emissions, were small, generally lower than detectable from space. Although past socio-economically driven emission reductions have eventually been apparent as changes to the growth rate of CO₂, simulations show that these changes are barely perceptible by space-borne or even in situ observations against ongoing natural variability. Subtle changes to concentrations are likely reflected nearly immediately on ocean uptake, but again these changes are unlikely to be observable, save in post-pandemic analyses of the global budget. Emission reductions of 20-30% - in effect, returning emissions to the level of a decade or so ago—are large, but would have to be sustained and increased to produce reductions in concentrations against the background of a century and a half of accumulated fossil CO₂. The pandemic provides new information on the impacts of future emission mitigation regimes, and observations needed to quantify and verify mitigation activities, as well as providing a perturbation experiment against which to test Earth System transient responses.