Global impact of anthropogenic NH <sub>3</sub> emissions on upper tropospheric aerosol formation

Anthropogenic ammonia (NH<sub>3</sub>) emissions have significantly increased in recent decades due to enhanced agricultural activities, contributing to global air pollution. While the effects of NH<sub>3</sub> on surface air quality are well documented, its influence on particle dynamics in the upper troposphere-lower stratosphere (UTLS) and related aerosol impacts remain unquantified. NH<sub>3</sub> reaches the UTLS through convective transport and can enhance new particle formation (NPF). This modeling study evaluates the global impact of anthropogenic NH<sub>3</sub> on UTLS particle formation and quantifies its effects on aerosol loading and cloud condensation nuclei (CCN) abundance. We use the EMAC Earth system model, incorporating multicomponent NPF parameterizations from the CERN CLOUD experiment. Our simulations reveal that convective transport increases NH<sub>3</sub>-driven NPF in the UTLS by one to three orders of magnitude compared to a baseline scenario without anthropogenic NH<sub>3</sub>, causing a doubling of aerosol numbers over high-emission regions. These aerosol changes induce a 2.5-fold increase in upper tropospheric CCN concentrations. Anthropogenic NH<sub>3</sub> emissions increase the relative contribution of water-soluble inorganic ions to the UTLS aerosol optical depth (AOD) by 20% and increase total column AOD by up to 80%. In simulations without anthropogenic NH<sub>3</sub>, UTLS aerosol composition is dominated by sulfate and organic species, with a marked reduction in ammonium nitrate and aerosol water content. This results in a decline of aerosol mass concentration by up to 50%. These findings underscore the profound global influence of anthropogenic NH<sub>3</sub> emissions on UTLS particle formation, AOD, and CCN production, with important implications for cloud formation and climate.

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Proceedings of the National Academy of Sciences
Published
2025-10-27
DOI
https://doi.org/10.1073/pnas.2506658122
Primary Topic
Atmospheric chemistry and aerosols
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article
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article

Global impact of anthropogenic NH 3 emissions on upper tropospheric aerosol formation

Markku Kulmala, P. Rato Mendes, Michael Höpfner, J. Kirkby et al.
Proceedings of the National Academy of Sciences
Atmospheric chemistry and aerosols
article

Global impact of anthropogenic NH 3 emissions on upper tropospheric aerosol formation

Markku Kulmala, P. Rato Mendes, Michael Höpfner, J. Kirkby, Richard C. Flagan, Rainer Volkamer, Katrianne Lehtipalo, Birte Rörup, Hartwig Harder, Mira L. Pöhlker, Wenjuan Yu, Yandong Tong, Douglas R. Worsnop, Jos Lelieveld, Joachim Curtius, Siegfried Schobesberger, Meredith Schervish, Lejish Vettikkat, Neil M. Donahue, Paul M. Winkler, Nsikanabasi Silas Umo, Xu‐Cheng He, Weimeng Kong, Lubna Dada, Sebastian Ehrhart, Rómulo Cruz-Simbrón, Eva Sommer, Dominik Stolzenburg, T. Christoudias, Tuukka Petäjä, Kristina Höhler, Wiebke Scholz, Matthias Kohl, Lucía Caudillo, Imad El Haddad, Henning Finkenzeller, Andrea Pozzer, Zhensen Zheng, Hamish Gordon, Mario Simon, Jonathan Duplissy, Antti Onnela, Armin Hansel, Ottmar Möhler, Bernhard Mentler, Gabriela R. Unfer, Imad Zgheib, Mingyi Wang, Boxing Yang, João Almeida, Christos Xenofontos, Felix Kunkler, Samuel Ruhl, Clara J. Lietzke, Douglas M. Russell, Milin Kaniyodical Sebastian, A. Morawiec
article en

Abstract

Anthropogenic ammonia (NH<sub>3</sub>) emissions have significantly increased in recent decades due to enhanced agricultural activities, contributing to global air pollution. While the effects of NH<sub>3</sub> on surface air quality are well documented, its influence on particle dynamics in the upper troposphere-lower stratosphere (UTLS) and related aerosol impacts remain unquantified. NH<sub>3</sub> reaches the UTLS through convective transport and can enhance new particle formation (NPF). This modeling study evaluates the global impact of anthropogenic NH<sub>3</sub> on UTLS particle formation and quantifies its effects on aerosol loading and cloud condensation nuclei (CCN) abundance. We use the EMAC Earth system model, incorporating multicomponent NPF parameterizations from the CERN CLOUD experiment. Our simulations reveal that convective transport increases NH<sub>3</sub>-driven NPF in the UTLS by one to three orders of magnitude compared to a baseline scenario without anthropogenic NH<sub>3</sub>, causing a doubling of aerosol numbers over high-emission regions. These aerosol changes induce a 2.5-fold increase in upper tropospheric CCN concentrations. Anthropogenic NH<sub>3</sub> emissions increase the relative contribution of water-soluble inorganic ions to the UTLS aerosol optical depth (AOD) by 20% and increase total column AOD by up to 80%. In simulations without anthropogenic NH<sub>3</sub>, UTLS aerosol composition is dominated by sulfate and organic species, with a marked reduction in ammonium nitrate and aerosol water content. This results in a decline of aerosol mass concentration by up to 50%. These findings underscore the profound global influence of anthropogenic NH<sub>3</sub> emissions on UTLS particle formation, AOD, and CCN production, with important implications for cloud formation and climate.

Proceedings of the National Academy of SciencesVol. 122(44)
Karlsruhe Institute of Technology (DE), Goethe University Frankfurt (DE), California Institute of Technology (US), Finnish Meteorological Institute (FI), University of Vienna (AT), Federal Office of Meteorology and Climatology MeteoSwiss (CH), University of Helsinki (FI), TU Wien (AT), Cyprus Institute (CY), Irvine Valley College (US), Cooperative Institute for Research in Environmental Sciences (US), University of Eastern Finland (FI), University of Colorado Boulder (US), Universität Innsbruck (AT), University of California, Irvine (US), University of Cambridge (GB), University Corporation for Atmospheric Research (US), Paul Scherrer Institute (CH), University of Colorado System (US), University of California System (US), University of Chicago (US), Ionicon Analytik (Austria) (AT), Institute of Particle Physics (CA), Laboratoire de Physico-Chimie de l'Atmosphère (FR), Tofwerk (Switzerland) (CH), Finland University (FI), Division of Chemistry (US), Aerodyne Research (US), Max Planck Institute for Chemistry (DE), Leibniz Institute for Tropospheric Research (DE), Irvine Unified School District (US), Institute of Biophysics (BG), Institute for Physics (US), Universitas Islam Syekh Yusuf (ID), Irvine University (US), Czech Academy of Sciences, Institute of Atmospheric Physics (CZ), National Institute of Meteorology (TN), Institute of Atmospheric Physics (CN), Atmospheric and Environmental Research (US), Beijing Advanced Sciences and Innovation Center (CN), European Organization for Nuclear Research (CH), Carnegie Mellon University (US), Beijing University of Chemical Technology (CN), Nanjing University (CN)
National Science Foundation, National Aeronautics and Space Administration, California Institute of Technology, Itä-Suomen Yliopisto, Helsingin Yliopisto, Carnegie Mellon University, CERN, European Commission, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Vienna Science and Technology Fund, Bundesministerium für Bildung und Forschung, Universität Wien, Nuclear Safety and Security Commission, Jane ja Aatos Erkon Säätiö, Oesterreichische Nationalbank, Paul Scherrer Institut, Beijing University of Chemical Technology, Nanjing University, Universität Innsbruck, University of Colorado Boulder, University of California, Irvine, HORIZON EUROPE Framework Programme, Leibniz-Gemeinschaft, Division of Chemistry, Leibniz-Institut für Troposphärenforschung, H2020 Marie Skłodowska-Curie Actions
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