@article{ac0f7915327348c7b3e6bf43f2425150,
title = "Societal shifts due to COVID-19 reveal large-scale complexities and feedbacks between atmospheric chemistry and climate change",
abstract = "The COVID-19 global pandemic and associated government lockdowns dramatically altered human activity, providing a window into how changes in individual behavior, enacted en masse, impact atmospheric composition. The resulting reductions in anthropogenic activity represent an unprecedented event that yields a glimpse into a future where emissions to the atmosphere are reduced. Furthermore, the abrupt reduction in emissions during the lockdown periods led to clearly observable changes in atmospheric composition, which provide direct insight into feedbacks between the Earth system and human activity. While air pollutants and greenhouse gases share many common anthropogenic sources, there is a sharp difference in the response of their atmospheric concentrations to COVID-19 emissions changes, due in large part to their different lifetimes. Here, we discuss several key takeaways from modeling and observational studies. First, despite dramatic declines in mobility and associated vehicular emissions, the atmospheric growth rates of greenhouse gases were not slowed, in part due to decreased ocean uptake of CO2 and a likely increase in CH4 lifetime from reduced NOx emissions. Second, the response of O3 to decreased NOx emissions showed significant spatial and temporal variability, due to differing chemical regimes around the world. Finally, the overall response of atmospheric composition to emissions changes is heavily modulated by factors including carbon-cycle feedbacks to CH4 and CO2, background pollutant levels, the timing and location of emissions changes, and climate feedbacks on air quality, such as wildfires and the ozone climate penalty.",
keywords = "Air quality, COVID-19, Earth system, Greenhouse gases, Mitigation",
author = "Laughner, {Joshua L.} and Neu, {Jessica L.} and David Schimel and Wennberg, {Paul O.} and Kelley Barsanti and Bowman, {Kevin W.} and Abhishek Chatterjee and Croes, {Bart E.} and Fitzmaurice, {Helen L.} and Henze, {Daven K.} and Jinsol Kim and Kort, {Eric A.} and Zhu Liu and Kazuyuki Miyazaki and Turner, {Alexander J.} and Susan Anenberg and Jeremy Avise and Hansen Cao and David Crisp and {De Gouw}, Joost and Annmarie Eldering and Fyfe, {John C.} and Goldberg, {Daniel L.} and Gurney, {Kevin R.} and Sina Hasheminassab and Francesca Hopkins and Ivey, {Cesunica E.} and Jones, {Dylan B.A.} and Junjie Liu and Lovenduski, {Nicole S.} and Martin, {Randall V.} and McKinley, {Galen A.} and Lesley Ott and Benjamin Poulter and Muye Ru and Sander, {Stanley P.} and Neil Swart and Yung, {Yuk L.} and Zeng, {Zhao Cheng}",
note = "Funding Information: ACKNOWLEDGMENTS. We thank the Keck Institute for Space Studies for organizing and supporting the study “COVID-19: Identifying Unique Opportunities for Earth System Science” that led to the writing of this manuscript. We also acknowledge the use of data from the Port of Oakland and Port of LA website, Apple mobility data, and US EIA electricity-use data. We also thank Charles Carter for his artwork in Fig. 1. We thank the TCCON science team for their effort in providing data. Support for operation of the Park Falls TCCON site is provided by NASA. The Lauder TCCON programme is funded by NIWA (National Institute of Water & Atmospheric Research Ltd.) through Aotearoa New Zealand{\textquoteright}s Ministry of Business, Innovation and Employment{\textquoteright}s Strategic Science Investment Fund. The views expressed in this manuscript are solely those of the authors and do not necessarily reflect those of the South Coast Air Quality Management District. A portion of this research was carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under a contract with NASA. This work was supported by NASA Grant NNX17AE15G (to J.L.L. and P.O.W.), NASA Carbon Monitoring System Grant 80NSSC20K0006 (to A.C.), NASA Grant 80NSSC18K0689 (to D.K.H. and H.C.), NASA Aura Science Team Program 19-AURAST19-0044 (to K.M. and K.W.B.), NASA Grant 80NSSC20K1122 (to D.L.G. and S.A.), NASA Grant 80NSSC21K0508 (to R.V.M.), NSF RAPID Grant 2030049 (to K.B.), NSF Grants OCE-1752724 and OCE-1948664 (to N.S.L.), and NSF Grant OCE-1948624 (to G.A.M.). A.J.T. was supported as a Miller Fellow with the Miller Institute for Basic Research in Science at the University of California Berkeley. K.R.G. was supported by Northern Arizona University startup funds. C.E.I. was supported by the University of California Institute of Transportation Studies. S.P.S. and Z.-C.Z. were supported by the California Air Resources Board, NASA Science Mission Directorate/Earth Science Division, and JPL Earth Science and Technology Directorate. Y.L.Y. was supported in part by JPL OCO-2 Grant JPL.1613918 (to the California Institute of Technology). J.L. was supported by the NASA OCO science team program. Publisher Copyright: {\textcopyright} 2021 National Academy of Sciences. All rights reserved.",
year = "2021",
month = nov,
day = "16",
doi = "10.1073/pnas.2109481118",
language = "English (US)",
volume = "118",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
publisher = "National Academy of Sciences",
number = "46",
}