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Radiative effects of reduced aerosol emissions during the COVID-19 pandemic and the future recovery
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  • Stephanie Fiedler,
  • Klaus Wyser,
  • Joeri Rogelj,
  • Twan van Noije
Stephanie Fiedler
University of Cologne

Corresponding Author:[email protected]

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Klaus Wyser
SMHI
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Joeri Rogelj
Imperial College London
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Twan van Noije
KNMI Royal Netherlands Meteorological Institute
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Abstract

The pandemic in 2020 caused an abrupt change in the emission of anthropogenic aerosols and their precursors. We provide the first estimate of the associated change in the aerosol radiative forcing at the top of the atmosphere and the surface. To this end, we perform new simulations with the contemporary Earth system model EC-Earth3 participating in CMIP6, and created new data on the anthropogenic aerosol optical properties and an associated effect on clouds for the implemented aerosol parameterization, MACv2-SP. Our results highlight the small impact of the pandemic on the global aerosol radiative forcing in 2020 compared to the baseline of the order of +0.04Wm-2, which is small compared to the natural year-to-year variability in the radiation budget. Natural variability also limits the ability to detect a meaningful regional difference in the anthropogenic aerosol radiative effects. We identify the best chances to find a significant change in radiation at the surface during cloud-free conditions for regions that were strongly polluted in the past years. The new post-pandemic recovery scenarios indicate a spread in the aerosol forcing of -0.68 to -0.38Wm-2 for 2050, which translates to a difference of +0.05 to -0.25Wm-2 compared to the baseline. This spread falls within the present-day uncertainty in aerosol radiative forcing and the CMIP6 spread in aerosol forcing at the end of the 21st century. We release the new MACv2-SP data for studies on the climate response to the pandemic and the recovery scenarios.
Dec 2021Published in Atmospheric Research volume 264 on pages 105866. 10.1016/j.atmosres.2021.105866