A081-08
Urban greenhouse gas emission response to COVID-19 shutdowns
Wednesday, 9 December 2020: 20:58
Virtual
Jocelyn C Turnbull1,2, Anna Karion3, Jooil Kim4, Kristal R Verhulst5, Vineet Yadav6, Charles E Miller6, Daniel Cusworth7, Ralph F Keeling4, Ray F Weiss4, Riley M Duren8, Natasha Miles9, Scott Richardson10, Kenneth J Davis11, Vanessa Monteiro9, Eli Vogel12, Shane Markus12, Israel Lopez-Coto3, Sharon Gourdji3, Subhomoy Ghosh3, Kimberly L Mueller3, Logan Mitchell13, John C Lin14, Maryann R Sargent15, Steven C Wofsy16 and Felix R Vogel17, (1)GNS Science, Lower Hutt, New Zealand, (2)University of Colorado at Boulder, CIRES, Boulder, United States, (3)National Institute of Standards and Technology Gaithersburg, Gaithersburg, MD, United States, (4)Scripps Institution of Oceanography, La Jolla, CA, United States, (5)JPL, Pasadena, CA, United States, (6)Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (7)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (8)University of Arizona, Tucson, AZ, United States, (9)Pennsylvania State University, Department of Meteorology and Atmospheric Science, University Park, PA, United States, (10)Pennsylvania State University, Department of Meteorology and Atmospheric Science, State College, PA, United States, (11)The Pennsylvania State University, University Park, PA, United States, (12)Pennsylvania State University Main Campus, University Park, United States, (13)University of Utah, Salt Lake City, United States, (14)University of Utah, Atmospheric Sciences, Salt Lake City, UT, United States, (15)Harvard University, Cambridge, MA, United States, (16)Harvard Univ, Cambridge, MA, United States, (17)Environment and Climate Change Canada, Climate Research Division, Toronto, Canada
Abstract:
COVID-related shutdowns resulted in dramatic reductions in anthropogenic emissions around the world. Globally the reduction in greenhouse gas (GHG) emissions, although substantial, may be challenging to detect in the atmospheric record due to other sources of seasonal and interannual variability. In contrast, urban atmospheric measurement networks can potentially detect urban GHG emission changes more readily due to the large concentration of emissions in cities.
Here we present results from atmospheric GHG observation networks across six North American metropolitan areas. Each city has long-term GHG observations at multiple sites running for several years and through the COVID shutdown period, with each city having similar but not identical experimental configurations. We use multiple observational analysis methods to detect the timing and magnitude of emission changes.
Reductions in carbon dioxide (CO2) emissions are apparent in most cities, although complications from varying meteorology and biogenic carbon fluxes make it difficult to infer the magnitude of these changes from observed CO2 enhancements alone. Emission ratios of CO2 to methane (CH4) suggest 10-20% reductions in CO2 emissions in some cities. Cumulative enhancement analysis allows us to detect the timing of the abrupt drop in emissions. Changes in carbon monoxide (CO) emissions are clearer than for CO2, likely because CO is not substantially impacted by biogenic emissions until later in the summer, and CO emissions from traffic (the sector with the largest drop due to the shutdowns) dominate most cities. No consistent pattern in CH4 emissions is apparent across all cities, suggesting that CH4 emission changes due to COVID are modest and/or variable. Local and micrometeorological measurements show the emissions changes more readily than urban scale metrics. Active ecosystems complicate the signature of the anthropogenic emissions changes.
This unplanned experiment clearly illustrates that atmospheric observation networks do enable quantitative assessment of month-to-month changes in urban GHG emissions. The integrated modeling and observational systems deployed for these urban experiments are necessary to provide quantitative estimation of the emissions changes.
