Decreases in 2020 carbon dioxide growth due to the Coronavirus pandemic observed from space

Abstract:

Observations of atmospheric carbon dioxide (CO₂) from the Orbiting Carbon Observatory 2 (OCO-2), assimilated into the Goddard Earth Observing System (GEOS), an integrated model of the Earth’s atmosphere, ocean, and land surface, reveals changes in February–April 2020 consistent with the unprecedented reduction in economic activity due to the Coronavirus disease 2019 (COVID-19) pandemic. During these three months, the growth in CO₂ over many of the World’s largest economies was roughly 0.3 ppm less than it was in the previous four years. This estimate includes considerable uncertainties. For example, over the same regions, inter-annual variability in atmospheric transport produces differences greater than 3 ppm. We use an analysis technique that accurately accounts for variations in transport, allowing us to infer regional CO₂ changes with estimated errors smaller than 0.3 ppm. Concurrent with the global pandemic, the 2019–2020 Indian Ocean Dipole index was the strongest on record, corresponding to flooding in India and East Africa and drought and fires in Australia. Teleconnections between climate variability and terrestrial biosphere surface exchange drove 0.3–0.5 ppm CO₂ anomalies over Africa, India, and Australia. This variability in consistent with that from other climate anomalies including the 2015–2016 El Niño/Southern Oscillation and 2015 Pacific warm pool. Observing and analyzing these changes, orders of magnitude smaller and shorter than the ~415 ppm background and ~100 year lifetime of CO₂, is a significant advance for present-day sensors and data assimilation systems. This is an encouraging step toward the goal of monitoring anthropogenic emissions, in the context of land and ocean variability, especially given planned future increases in observational coverage.