Articles | Volume 23, issue 1
https://doi.org/10.5194/acp-23-687-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-23-687-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
16 Jan 2023
Research article |
| 16 Jan 2023
| 16 Jan 2023
Climate response to off-equatorial stratospheric sulfur injections in three Earth system models – Part 2: Stratospheric and free-tropospheric response
Sibley School of Mechanical and Aerospace Engineering, Cornell
University, Ithaca, NY, USA
now at: Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, CO, USA
now at: NOAA Chemical Sciences
Laboratory, Boulder, CO, USA
Daniele Visioni
Sibley School of Mechanical and Aerospace Engineering, Cornell
University, Ithaca, NY, USA
Ben Kravitz
Department of Earth and Atmospheric Sciences, Indiana University,
Bloomington, IN, USA
Atmospheric Sciences and Global Change Division, Pacific Northwest
National Laboratory, Richland, WA, USA
Andy Jones
Met Office Hadley Centre, Exeter, UK
James M. Haywood
Met Office Hadley Centre, Exeter, UK
College of Engineering, Maths and Physical Science, University of Exeter,
Exeter, UK
Jadwiga Richter
National Center for Atmospheric Research, Climate and Global Dynamics Laboratory, Boulder, CO, USA
Douglas G. MacMartin
Sibley School of Mechanical and Aerospace Engineering, Cornell
University, Ithaca, NY, USA
Peter Braesicke
IMK-ASF, Karlsruhe Institute of Technology, Eggenstein–Leopoldshafen,
Germany
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Walker Raymond Lee, Simone Tilmes, and Ewa M. Bednarz
EGUsphere, https://doi.org/10.5194/egusphere-2026-1004, https://doi.org/10.5194/egusphere-2026-1004, 2026
This preprint is open for discussion and under review for Earth System Dynamics (ESD).
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We present climate model simulation of stratospheric aerosol injection, a proposed method of climate intervention where reflective particles are placed in the stratosphere to cool the planet. We design our simulated interventions to maintain certain surface temperature patterns, and show that the same temperatures can be maintained in different ways because of how the ocean transports heat. This has implications for how climate intervention model experiments are designed in the future.
Jared Farley, Douglas G. MacMartin, Daniele Visioni, Ben Kravitz, Ewa M. Bednarz, Alistair Duffey, Matthew Henry, and Ali Akherati
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Sean Davis, William Ball, Yue Jia, Gabriel Chiodo, Justin Alsing, James Keeble, Hideharu Akiyoshi, Carlo Arosio, Ewa Bednarz, Andreas Chrysanthou, Melanie Coldewey-Egbers, Robert Damadeo, Sandip Dhomse, Mohamadou Diallo, Simone Dietmuller, Roland Eichinger, Stacey Frith, Birgit Hassler, Michaela Hegglin, Daan Hubert, Patrick Jöckel, Béatrice Josse, Natalya Kramarova, Diego Loyola, Eliane Maillard Barras, Marion Marchand, Olaf Morgenstern, David Plummer, Robert Portmann, Karen Rosenlof, Alexei Rozanov, Viktoria Sofieva, Johannes Staehelin, Timofei Sukhodolov, Kleareti Tourpali, Ronald Van der A, H. J. Ray Wang, Krzysztof Wargan, Shingo Watanabe, Mark Weber, Jeannette Wild, Yousuke Yamashita, and Jerry Ziemke
EGUsphere, https://doi.org/10.5194/egusphere-2026-532, https://doi.org/10.5194/egusphere-2026-532, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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This study investigates how tropical ozone levels have changed since 2000 in chemistry climate models and satellite observations to determine how well they agree with one another, and to see if current trends can help predict future levels. At some, satellite records disagree significantly on the magnitude of ozone changes. The study shows a connection between recent ozone trends and future ozone levels, suggesting that satellite measurements could help constrain future ozone changes.
Martin B. Andrews, Neal Butchart, James A. Anstey, Ewa Bednarz, Dillon Elsbury, Jorge L. García-Franco, Vinay Kumar, Froila M. Palmeiro, Natasha E. Trencham, Kohei Yoshida, Zhaoyang Chai, Dong-Chan Hong, Kai Huang, Aleena M. Jaison, Yoshio Kawatani, Jeff R. Knight, Pu Lin, François Lott, Yixiong Lu, Hiroaki Naoe, Scott M. Osprey, Jadwiga H. Richter, Federico Serva, Seok-Woo Son, Qi Tang, Shingo Watanabe, and Jinbo Xie
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This preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).
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The observed winds in the upper atmosphere over the equator have alternating easterly and westerly regions that descend towards the lower atmosphere before dissipating, with a period of approximately 28 months. This is known as the Quasi-Biennial Oscillation (QBO). The QBO is known to influence remote regions of the atmosphere. This paper details the results of multi-model experiments where the QBO is nudged towards the observed QBO allowing the assessment of these remote connections.
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EGUsphere, https://doi.org/10.5194/egusphere-2026-444, https://doi.org/10.5194/egusphere-2026-444, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Cindy Wang, Daniele Visioni, Glen Chua, and Ewa M. Bednarz
Atmos. Chem. Phys., 26, 1339–1357, https://doi.org/10.5194/acp-26-1339-2026, https://doi.org/10.5194/acp-26-1339-2026, 2026
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Stratospheric aerosol injection is a proposed method to slow global warming by adding tiny reflective particles high up in the atmosphere to cool the planet. We study how this proposed method might affect air quality and human health using climate models. We find that the health impacts would likely be small and are mainly driven by changes in climate, not by the particles themselves.
Ewa M. Bednarz, Amy H. Butler, James M. Haywood, Matthew Henry, Andy Jones, Ben Kravitz, Walker R. Lee, Douglas G. MacMartin, Amanda C. Maycock, Takashi Sekiya, Shingo Watanabe, and Daniele Visioni
EGUsphere, https://doi.org/10.5194/egusphere-2026-310, https://doi.org/10.5194/egusphere-2026-310, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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An assessment of the potential impacts of Stratospheric Aerosol Injection, a proposed method to offset global warming, on stratospheric ozone projections over the 21st century using the new multi-model GeoMIP G6-1.5K-SAI experiment. We discuss drivers of the responses, identify areas of model agreement and disagreement and sources of uncertainty. Our results highlight the need to assess any projected SAI impacts in wider strategy and scenario dimension using a multi-model framework.
Clara Orbe, Alison Ming, Gabriel Chiodo, Michael Prather, Mohamadou Diallo, Qi Tang, Andreas Chrysanthou, Hiroaki Naoe, Xin Zhou, Irina Thaler, Dillon Elsbury, Ewa Bednarz, Jonathon S. Wright, Aaron Match, Shingo Watanabe, James Anstey, Tobias Kerzenmacher, Stefan Versick, Marion Marchand, Feng Li, and James Keeble
Geosci. Model Dev., 19, 773–794, https://doi.org/10.5194/gmd-19-773-2026, https://doi.org/10.5194/gmd-19-773-2026, 2026
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The quasi-biennial oscillation (QBO) is the main source of wind fluctuations in the tropical stratosphere, which can couple to surface climate. However, models do a poor job of simulating the QBO in the lower stratosphere, for reasons that remain unclear. One possibility is that models do not completely represent how ozone influences the QBO-associated wind variations. Here we propose a multi-model framework for assessing how ozone influences the QBO in recent past and future climates.
Ewa M. Bednarz, Amy H. Butler, Xinyue Wang, Zhihong Zhuo, Wandi Yu, Georgiy Stenchikov, Matthew Toohey, and Yunqian Zhu
Atmos. Chem. Phys., 26, 197–215, https://doi.org/10.5194/acp-26-197-2026, https://doi.org/10.5194/acp-26-197-2026, 2026
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We investigate whether the 2022 Hunga eruption could affect surface climate via indirect pathways using large ensembles of Earth System Model simulations. These suggest that the eruption could have a non-negligible influence on regional surface climate, and we discuss the mechanisms via which such an influence could occur but also highlight that the forcing is relatively weak compared to natural climate variability which significantly hinders the detection of such impacts in the real world.
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Stratospheric aerosol injection (SAI) is a proposed method of cooling the planet by introducing reflective particles called aerosols into the middle atmosphere to reflect sunlight back into space. We consider recent simulations of SAI from four different climate models. SAI cools the planet effectively in all four models; we examine the impacts on temperature and precipitation in each model and compare to previous experiments. Our simulations will help inform future research and policy.
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EGUsphere, https://doi.org/10.5194/egusphere-2025-4609, https://doi.org/10.5194/egusphere-2025-4609, 2025
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The 2022 Hunga eruption injected unprecedented quantities of water vapor into the stratosphere, alongside modest amounts of aerosol precursors. We assess its impacts on stratospheric ozone layer using a multi-model ensemble of chemistry-climate simulations. The results confirm the eruption's role in modulating SH mid and high latitudes ozone abundances in the short term, and discuss the different chemical and dynamical processes driving those changes as well as the role of natural variability.
Zhihong Zhuo, Xinyue Wang, Yunqian Zhu, Wandi Yu, Ewa M. Bednarz, Eric Fleming, Peter R. Colarco, Shingo Watanabe, David Plummer, Georgiy Stenchikov, William Randel, Adam Bourassa, Valentina Aquila, Takashi Sekiya, Mark R. Schoeberl, Simone Tilmes, Jun Zhang, Paul J. Kushner, and Francesco S. R. Pausata
Atmos. Chem. Phys., 25, 13161–13176, https://doi.org/10.5194/acp-25-13161-2025, https://doi.org/10.5194/acp-25-13161-2025, 2025
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The 2022 Hunga eruption caused unprecedented stratospheric water injection, triggering unique atmospheric impacts. This study combines observations and model simulations, projecting a stratospheric water vapor anomaly lasting 4–7 years, with significant temperature variations and ozone depletion in the upper atmosphere lasting 7–10 years. These findings offer critical insights into the role of stratospheric water vapor in shaping climate and atmospheric chemistry.
Ilaria Quaglia, Daniele Visioni, Ewa M. Bednarz, Yunqian Zhu, Georgiy Stenchikov, Valentina Aquila, Cheng-Cheng Liu, Graham W. Mann, Yifeng Peng, Takashi Sekiya, Simone Tilmes, Xinyue Wang, Shingo Watanabe, Pengfei Yu, Jun Zhang, and Wandi Yu
EGUsphere, https://doi.org/10.5194/egusphere-2025-3769, https://doi.org/10.5194/egusphere-2025-3769, 2025
Short summary
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On January 15, 2022, the Hunga volcano eruption released unprecedented amounts of water vapor into the atmosphere alongside a modest amount of SO2. In this work we analyse results from multiple Earth system models. The models agree that the eruption led to small negative radiative forcing from sulfate aerosols and that the contribution from water vapor was minimal. Therefore, the Hunga eruption cannot explain the exceptional surface warming observed in 2023.
Yunqian Zhu, Hideharu Akiyoshi, Valentina Aquila, Elizabeth Asher, Ewa M. Bednarz, Slimane Bekki, Christoph Brühl, Amy H. Butler, Parker Case, Simon Chabrillat, Gabriel Chiodo, Margot Clyne, Peter R. Colarco, Sandip Dhomse, Lola Falletti, Eric Fleming, Ben Johnson, Andrin Jörimann, Mahesh Kovilakam, Gerbrand Koren, Ales Kuchar, Nicolas Lebas, Qing Liang, Cheng-Cheng Liu, Graham Mann, Michael Manyin, Marion Marchand, Olaf Morgenstern, Paul Newman, Luke D. Oman, Freja F. Østerstrøm, Yifeng Peng, David Plummer, Ilaria Quaglia, William Randel, Samuel Rémy, Takashi Sekiya, Stephen Steenrod, Timofei Sukhodolov, Simone Tilmes, Kostas Tsigaridis, Rei Ueyama, Daniele Visioni, Xinyue Wang, Shingo Watanabe, Yousuke Yamashita, Pengfei Yu, Wandi Yu, Jun Zhang, and Zhihong Zhuo
Geosci. Model Dev., 18, 5487–5512, https://doi.org/10.5194/gmd-18-5487-2025, https://doi.org/10.5194/gmd-18-5487-2025, 2025
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To understand the climate impact of the 2022 Hunga volcanic eruption, we developed a climate model–observation comparison project. The paper describes the protocols and models that participate in the experiments. We designed several experiments to achieve our goals of this activity: (1) to evaluate the climate model performance and (2) to understand the Earth system responses to this eruption.
Ezra Brody, Yan Zhang, Douglas G. MacMartin, Daniele Visioni, Ben Kravitz, and Ewa M. Bednarz
Earth Syst. Dynam., 16, 1325–1341, https://doi.org/10.5194/esd-16-1325-2025, https://doi.org/10.5194/esd-16-1325-2025, 2025
Short summary
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Stratospheric aerosol injection (SAI) is being studied as a possible supplement to emission reduction to temporarily mitigate some of the risks associated with climate change. The latitudes at which SAI is done determine the effect on the climate. We try to find if there are combinations of latitudes that do a better job of counteracting climate change than existing strategies. We found that there are, but just how significant these improvements are depends on the amount of cooling.
Simone Tilmes, Ewa M. Bednarz, Andrin Jörimann, Daniele Visioni, Douglas E. Kinnison, Gabriel Chiodo, and David Plummer
Atmos. Chem. Phys., 25, 6001–6023, https://doi.org/10.5194/acp-25-6001-2025, https://doi.org/10.5194/acp-25-6001-2025, 2025
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In this paper, we describe the details of a new multi-model intercomparison experiment to assess the effects of Stratospheric Aerosol Intervention (SAI) on stratospheric chemistry and dynamics and, therefore, ozone. Second, we discuss the advantages and differences of the more constrained experiment compared to fully interactive model experiments. This way, we advance the process-level understanding of the drivers of SAI-induced atmospheric responses.
Matthew Henry, Ewa M. Bednarz, and Jim Haywood
Atmos. Chem. Phys., 24, 13253–13268, https://doi.org/10.5194/acp-24-13253-2024, https://doi.org/10.5194/acp-24-13253-2024, 2024
Short summary
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Stratospheric aerosol injection (SAI) refers to a climate intervention by which aerosols are intentionally added to the high atmosphere to increase the amount of reflected sunlight and reduce Earth's temperature. The climate outcomes of SAI depend on the latitude of injection. While injecting aerosols at the Equator has undesirable side effects, injecting away from the Equator has different effects on temperature, rainfall, ozone, and atmospheric circulation, which are analysed in this work.
Yan Zhang, Douglas G. MacMartin, Daniele Visioni, Ewa M. Bednarz, and Ben Kravitz
Earth Syst. Dynam., 15, 191–213, https://doi.org/10.5194/esd-15-191-2024, https://doi.org/10.5194/esd-15-191-2024, 2024
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Injecting SO2 into the lower stratosphere can temporarily reduce global mean temperature and mitigate some risks associated with climate change, but injecting it at different latitudes and seasons would have different impacts. This study introduces new stratospheric aerosol injection (SAI) strategies and explores the importance of the choice of SAI strategy, demonstrating that it notably affects the distribution of aerosol cloud, injection efficiency, and various surface climate impacts.
Ewa M. Bednarz, Amy H. Butler, Daniele Visioni, Yan Zhang, Ben Kravitz, and Douglas G. MacMartin
Atmos. Chem. Phys., 23, 13665–13684, https://doi.org/10.5194/acp-23-13665-2023, https://doi.org/10.5194/acp-23-13665-2023, 2023
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We use a state-of-the-art Earth system model and a set of stratospheric aerosol injection (SAI) strategies to achieve the same level of global mean surface cooling through different combinations of location and/or timing of the injection. We demonstrate that the choice of SAI strategy can lead to contrasting impacts on stratospheric and tropospheric temperatures, circulation, and chemistry (including stratospheric ozone), thereby leading to different impacts on regional surface climate.
Ewa M. Bednarz, Ryan Hossaini, and Martyn P. Chipperfield
Atmos. Chem. Phys., 23, 13701–13711, https://doi.org/10.5194/acp-23-13701-2023, https://doi.org/10.5194/acp-23-13701-2023, 2023
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We quantify, for the first time, the time-varying impact of uncontrolled emissions of chlorinated very short-lived substances (Cl-VSLSs) on stratospheric ozone using a state-of-the-art chemistry-climate model. We demonstrate that Cl-VSLSs already have a non-negligible impact on stratospheric ozone, including a local reduction of up to ~7 DU in Arctic ozone in the cold winter of 2019/20, and any so future growth in emissions will continue to offset some of the benefits of the Montreal Protocol.
Ewa M. Bednarz, Ryan Hossaini, N. Luke Abraham, and Martyn P. Chipperfield
Geosci. Model Dev., 16, 6187–6209, https://doi.org/10.5194/gmd-16-6187-2023, https://doi.org/10.5194/gmd-16-6187-2023, 2023
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Development and performance of the new DEST chemistry scheme of UM–UKCA is described. The scheme extends the standard StratTrop scheme by including important updates to the halogen chemistry, thus allowing process-oriented studies of stratospheric ozone depletion and recovery, including impacts from both controlled long-lived ozone-depleting substances and emerging issues around uncontrolled, very short-lived substances. It will thus aid studies in support of future ozone assessment reports.
Matthew Henry, Jim Haywood, Andy Jones, Mohit Dalvi, Alice Wells, Daniele Visioni, Ewa M. Bednarz, Douglas G. MacMartin, Walker Lee, and Mari R. Tye
Atmos. Chem. Phys., 23, 13369–13385, https://doi.org/10.5194/acp-23-13369-2023, https://doi.org/10.5194/acp-23-13369-2023, 2023
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Solar climate interventions, such as injecting sulfur in the stratosphere, may be used to offset some of the adverse impacts of global warming. We use two independently developed Earth system models to assess the uncertainties around stratospheric sulfur injections. The injection locations and amounts are optimized to maintain the same pattern of surface temperature. While both models show reduced warming, the change in rainfall patterns (even without sulfur injections) is uncertain.
Daniele Visioni, Ewa M. Bednarz, Walker R. Lee, Ben Kravitz, Andy Jones, Jim M. Haywood, and Douglas G. MacMartin
Atmos. Chem. Phys., 23, 663–685, https://doi.org/10.5194/acp-23-663-2023, https://doi.org/10.5194/acp-23-663-2023, 2023
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The paper constitutes Part 1 of a study performing a first systematic inter-model comparison of the atmospheric responses to stratospheric sulfate aerosol injections (SAIs) at various latitudes as simulated by three state-of-the-art Earth system models. We identify similarities and differences in the modeled aerosol burden, investigate the differences in the aerosol approaches between the models, and ultimately show the differences produced in surface climate, temperature and precipitation.
Ewa M. Bednarz, Ryan Hossaini, Martyn P. Chipperfield, N. Luke Abraham, and Peter Braesicke
Atmos. Chem. Phys., 22, 10657–10676, https://doi.org/10.5194/acp-22-10657-2022, https://doi.org/10.5194/acp-22-10657-2022, 2022
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Atmospheric impacts of chlorinated very short-lived substances (Cl-VSLS) over the first two decades of the 21st century are assessed using the UM-UKCA chemistry–climate model. Stratospheric input of Cl from Cl-VSLS is estimated at ~130 ppt in 2019. The use of model set-up with constrained meteorology significantly increases the abundance of Cl-VSLS in the lower stratosphere relative to the free-running set-up. The growth in Cl-VSLS emissions significantly impacted recent HCl and COCl2 trends.
Simone Tilmes, Daniele Visioni, Andy Jones, James Haywood, Roland Séférian, Pierre Nabat, Olivier Boucher, Ewa Monica Bednarz, and Ulrike Niemeier
Atmos. Chem. Phys., 22, 4557–4579, https://doi.org/10.5194/acp-22-4557-2022, https://doi.org/10.5194/acp-22-4557-2022, 2022
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This study assesses the impacts of climate interventions, using stratospheric sulfate aerosol and solar dimming on stratospheric ozone, based on three Earth system models with interactive stratospheric chemistry. The climate interventions have been applied to a high emission (baseline) scenario in order to reach global surface temperatures of a medium emission scenario. We find significant increases and decreases in total column ozone, depending on regions and seasons.
Walker Raymond Lee, Simone Tilmes, and Ewa M. Bednarz
EGUsphere, https://doi.org/10.5194/egusphere-2026-1004, https://doi.org/10.5194/egusphere-2026-1004, 2026
This preprint is open for discussion and under review for Earth System Dynamics (ESD).
Short summary
Short summary
We present climate model simulation of stratospheric aerosol injection, a proposed method of climate intervention where reflective particles are placed in the stratosphere to cool the planet. We design our simulated interventions to maintain certain surface temperature patterns, and show that the same temperatures can be maintained in different ways because of how the ocean transports heat. This has implications for how climate intervention model experiments are designed in the future.
Jared Farley, Douglas G. MacMartin, Daniele Visioni, Ben Kravitz, Ewa M. Bednarz, Alistair Duffey, Matthew Henry, and Ali Akherati
Geosci. Model Dev., 19, 1809–1831, https://doi.org/10.5194/gmd-19-1809-2026, https://doi.org/10.5194/gmd-19-1809-2026, 2026
Short summary
Short summary
As the climate changes, many are studying sunlight reflection as a potential method of cooling. Such climate intervention could be deployed in many possible ways, including in scenarios where not every actor agrees on the strategy of cooling. These scenarios are so diverse that to explore all of them using earth system models proves to be too costly. In this paper, we develop a simplified climate model that allows users to easily explore climate intervention scenarios of their choice.
Sean Davis, William Ball, Yue Jia, Gabriel Chiodo, Justin Alsing, James Keeble, Hideharu Akiyoshi, Carlo Arosio, Ewa Bednarz, Andreas Chrysanthou, Melanie Coldewey-Egbers, Robert Damadeo, Sandip Dhomse, Mohamadou Diallo, Simone Dietmuller, Roland Eichinger, Stacey Frith, Birgit Hassler, Michaela Hegglin, Daan Hubert, Patrick Jöckel, Béatrice Josse, Natalya Kramarova, Diego Loyola, Eliane Maillard Barras, Marion Marchand, Olaf Morgenstern, David Plummer, Robert Portmann, Karen Rosenlof, Alexei Rozanov, Viktoria Sofieva, Johannes Staehelin, Timofei Sukhodolov, Kleareti Tourpali, Ronald Van der A, H. J. Ray Wang, Krzysztof Wargan, Shingo Watanabe, Mark Weber, Jeannette Wild, Yousuke Yamashita, and Jerry Ziemke
EGUsphere, https://doi.org/10.5194/egusphere-2026-532, https://doi.org/10.5194/egusphere-2026-532, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
Short summary
Short summary
This study investigates how tropical ozone levels have changed since 2000 in chemistry climate models and satellite observations to determine how well they agree with one another, and to see if current trends can help predict future levels. At some, satellite records disagree significantly on the magnitude of ozone changes. The study shows a connection between recent ozone trends and future ozone levels, suggesting that satellite measurements could help constrain future ozone changes.
Blanca Ayarzagüena, Amy H. Butler, Peter Hitchcock, Chaim I. Garfinkel, Zac D. Lawrence, Wuhan Ning, Philip Rupp, Zheng Wu, Hilla Afargan-Gerstman, Natalia Calvo, Alvaro de la Cámara, Martin Jucker, Gerbrand Koren, Daniel De Maeseneire, Gloria L. Manney, Marisol Osman, Masakazu Taguchi, Cory Barton, Dong-Chan Hong, Yu-Kyung Hyun, Hera Kim, Jeff Knight, Piero Malguzzi, Daniele Mastrangelo, Jiyoung Oh, Inna Polichtchouk, Jadwiga H. Richter, Isla R. Simpson, Seok-Woo Son, Damien Specq, and Tim Stockdale
Weather Clim. Dynam., 7, 411–437, https://doi.org/10.5194/wcd-7-411-2026, https://doi.org/10.5194/wcd-7-411-2026, 2026
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Sudden Stratospheric Warmings (SSWs) are known to follow a sustained wave dissipation in the stratosphere, which depends on both the tropospheric and stratospheric states. However, the relative role of each state is still unclear. Using a new set of subseasonal to seasonal forecasts, we show that the stratospheric state does not drastically affect the precursors of three recent SSWs, but modulates the stratospheric wave activity, with impacts depending on SSW features.
Simone Tilmes, Daniele Visioni, Ilaria Quaglia, Yunqian Zhu, Charles G. Bardeen, Francis Vitt, and Pengfei Yu
Atmos. Chem. Phys., 26, 2649–2666, https://doi.org/10.5194/acp-26-2649-2026, https://doi.org/10.5194/acp-26-2649-2026, 2026
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This study compares two sets of stratospheric aerosol injection (SAI) experiments using the same modeling framework, differing only in their aerosol microphysical schemes. Results show that these two schemes can yield substantially different aerosol burdens, radiative changes, and impacts when simulating the same injection scenarios. These findings suggest that more sophisticated aerosol models may be necessary to accurately assess the efficacy, side effects, and climate impacts of SAI.
Martin B. Andrews, Neal Butchart, James A. Anstey, Ewa Bednarz, Dillon Elsbury, Jorge L. García-Franco, Vinay Kumar, Froila M. Palmeiro, Natasha E. Trencham, Kohei Yoshida, Zhaoyang Chai, Dong-Chan Hong, Kai Huang, Aleena M. Jaison, Yoshio Kawatani, Jeff R. Knight, Pu Lin, François Lott, Yixiong Lu, Hiroaki Naoe, Scott M. Osprey, Jadwiga H. Richter, Federico Serva, Seok-Woo Son, Qi Tang, Shingo Watanabe, and Jinbo Xie
EGUsphere, https://doi.org/10.5194/egusphere-2026-737, https://doi.org/10.5194/egusphere-2026-737, 2026
This preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).
Short summary
Short summary
The observed winds in the upper atmosphere over the equator have alternating easterly and westerly regions that descend towards the lower atmosphere before dissipating, with a period of approximately 28 months. This is known as the Quasi-Biennial Oscillation (QBO). The QBO is known to influence remote regions of the atmosphere. This paper details the results of multi-model experiments where the QBO is nudged towards the observed QBO allowing the assessment of these remote connections.
Dillon Elsbury, Federico Serva, Julie M. Caron, Seung-Yoon Back, Clara Orbe, Jadwiga H. Richter, James A. Anstey, Neal Butchart, Chih-Chieh Chen, Javier García-Serrano, Anne Glanville, Yoshio Kawatani, Tobias Kerzenmacher, Francois Lott, Hiroaki Naoe, Scott Osprey, Froila M. Palmeiro, Seok-Woo Son, Masakazu Taguchi, Stefan Versick, Shingo Watanabe, and Kohei Yoshida
Weather Clim. Dynam., 7, 317–339, https://doi.org/10.5194/wcd-7-317-2026, https://doi.org/10.5194/wcd-7-317-2026, 2026
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We used climate models to test how constant El Niño and La Niña ocean conditions shape the Madden-Julian Oscillation during northern winter. El Niño made this weather pattern move faster, while La Niña slowed it down. The Quasi-Biennial Oscillation, a repeating wind pattern high in the atmosphere, had little effect. This shows that long-lasting ocean conditions mainly drive the changes we found.
Andrin Jörimann, Timofei Sukhodolov, Simone Tilmes, David Plummer, Shingo Watanabe, Hideharu Akiyoshi, Gabriel Chiodo, Daniele Visioni, Sandro Vattioni, Eugene Rozanov, Ewa M. Bednarz, Béatrice Jossé, Yousuke Yamashita, and Thomas Peter
EGUsphere, https://doi.org/10.5194/egusphere-2026-444, https://doi.org/10.5194/egusphere-2026-444, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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We study a future scenario where artificial stratospheric aerosol injections counter medium climate change, to understand possible negative side effects like ozone depletion. The injected aerosol layer is implemented uniformly in five climate models, which eliminates some uncertainty from model-specific aerosol evolution. The models agree well on where and how key thermodynamical (heating, circulation) and chemical processes change, however, the strength of the change varies considerably.
Cindy Wang, Daniele Visioni, Glen Chua, and Ewa M. Bednarz
Atmos. Chem. Phys., 26, 1339–1357, https://doi.org/10.5194/acp-26-1339-2026, https://doi.org/10.5194/acp-26-1339-2026, 2026
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Stratospheric aerosol injection is a proposed method to slow global warming by adding tiny reflective particles high up in the atmosphere to cool the planet. We study how this proposed method might affect air quality and human health using climate models. We find that the health impacts would likely be small and are mainly driven by changes in climate, not by the particles themselves.
Ewa M. Bednarz, Amy H. Butler, James M. Haywood, Matthew Henry, Andy Jones, Ben Kravitz, Walker R. Lee, Douglas G. MacMartin, Amanda C. Maycock, Takashi Sekiya, Shingo Watanabe, and Daniele Visioni
EGUsphere, https://doi.org/10.5194/egusphere-2026-310, https://doi.org/10.5194/egusphere-2026-310, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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An assessment of the potential impacts of Stratospheric Aerosol Injection, a proposed method to offset global warming, on stratospheric ozone projections over the 21st century using the new multi-model GeoMIP G6-1.5K-SAI experiment. We discuss drivers of the responses, identify areas of model agreement and disagreement and sources of uncertainty. Our results highlight the need to assess any projected SAI impacts in wider strategy and scenario dimension using a multi-model framework.
Clara Orbe, Alison Ming, Gabriel Chiodo, Michael Prather, Mohamadou Diallo, Qi Tang, Andreas Chrysanthou, Hiroaki Naoe, Xin Zhou, Irina Thaler, Dillon Elsbury, Ewa Bednarz, Jonathon S. Wright, Aaron Match, Shingo Watanabe, James Anstey, Tobias Kerzenmacher, Stefan Versick, Marion Marchand, Feng Li, and James Keeble
Geosci. Model Dev., 19, 773–794, https://doi.org/10.5194/gmd-19-773-2026, https://doi.org/10.5194/gmd-19-773-2026, 2026
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The quasi-biennial oscillation (QBO) is the main source of wind fluctuations in the tropical stratosphere, which can couple to surface climate. However, models do a poor job of simulating the QBO in the lower stratosphere, for reasons that remain unclear. One possibility is that models do not completely represent how ozone influences the QBO-associated wind variations. Here we propose a multi-model framework for assessing how ozone influences the QBO in recent past and future climates.
Ewa M. Bednarz, Amy H. Butler, Xinyue Wang, Zhihong Zhuo, Wandi Yu, Georgiy Stenchikov, Matthew Toohey, and Yunqian Zhu
Atmos. Chem. Phys., 26, 197–215, https://doi.org/10.5194/acp-26-197-2026, https://doi.org/10.5194/acp-26-197-2026, 2026
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We investigate whether the 2022 Hunga eruption could affect surface climate via indirect pathways using large ensembles of Earth System Model simulations. These suggest that the eruption could have a non-negligible influence on regional surface climate, and we discuss the mechanisms via which such an influence could occur but also highlight that the forcing is relatively weak compared to natural climate variability which significantly hinders the detection of such impacts in the real world.
Anthony C. Jones, James M. Haywood, Matthew Henry, and Alistair Duffey
EGUsphere, https://doi.org/10.5194/egusphere-2025-6332, https://doi.org/10.5194/egusphere-2025-6332, 2026
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Injecting aerosol into the stratosphere has been suggested to rapidly cool the planet and counter climate change. Rival actors who oppose deployment may seek to counter stratospheric aerosol injection. Using a climate model, we investigate whether stratospheric aerosol removal could be hastened by injecting coarse aerosol which promote aerosol growth and gravitational settling. We find that this could be effective, reducing aerosol impacts by 30 % in simulations, and warrants further research.
Katharina Perny, Timofei Sukhodolov, Ales Kuchar, Pavle Arsenovic, Bernadette Rosati, Christoph Brühl, Sandip S. Dhomse, Andrin Jörimann, Anton Laakso, Graham Mann, Ulrike Niemeier, Giovanni Pitari, Ilaria Quaglia, Takashi Sekiya, Kengo Sudo, Claudia Timmreck, Simone Tilmes, Daniele Visioni, and Harald E. Rieder
EGUsphere, https://doi.org/10.5194/egusphere-2025-5915, https://doi.org/10.5194/egusphere-2025-5915, 2025
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Major volcanic eruptions, such as the one of Mt. Pinatubo in 1991, can inject large amounts of sulfur dioxide into the stratosphere. The resulting aerosol cloud affects stratospheric temperature and thereby middle atmospheric dynamics and chemistry. Here we investigate similarities and differences across an ensemble of climate models in reproducing the stratospheric temperature signal following the Mt. Pinatubo eruption.
Alex M. Mason, Matthew Henry, Haruki Hirasawa, Fiona M. O'Connor, and James Haywood
EGUsphere, https://doi.org/10.5194/egusphere-2025-5591, https://doi.org/10.5194/egusphere-2025-5591, 2025
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Marine Cloud Brightening (MCB) proposes the spraying of sea salt particles into marine clouds to cool the planet. MCB in midlatitude regions in models gave a relatively even climate response. We use 42 simulations of MCB to target several climate responses. Two optimised combinations are compared to a midlatitude MCB simulation, which improved sea ice restoration and the temperature response pattern, highlighting the importance of high latitude MCB for MCB optimisation in this model.
Huihui Wu, Fanny Peers, Jonathan W. Taylor, Chenjie Yu, Steven J. Abel, Paul A. Barrett, Jamie Trembath, Keith Bower, Jim M. Haywood, and Hugh Coe
Atmos. Chem. Phys., 25, 16589–16609, https://doi.org/10.5194/acp-25-16589-2025, https://doi.org/10.5194/acp-25-16589-2025, 2025
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This study investigates the transport history of African Biomass-Burning aerosols (BBAs) over the Southeast Atlantic (SEA) and their impacts on cloud properties. Using in situ airborne measurements around Ascension Island, this work provides critical parameterizations of aerosol–cloud interactions to improve the assessment of radiative forcing in the SEA region. It also identifies key entrainment regions for understanding the vertical transport process of African BBAs.
Walker Raymond Lee, Daniele Visioni, Benjamin Moore Wagman, Christopher Robert Wentland, Ben Kravitz, Shingo Watanabe, Takashi Sekiya, Andy Jones, Jim Haywood, Matthew Henry, and Ewa Monika Bednarz
EGUsphere, https://doi.org/10.5194/egusphere-2025-5742, https://doi.org/10.5194/egusphere-2025-5742, 2025
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Stratospheric aerosol injection (SAI) is a proposed method of cooling the planet by introducing reflective particles called aerosols into the middle atmosphere to reflect sunlight back into space. We consider recent simulations of SAI from four different climate models. SAI cools the planet effectively in all four models; we examine the impacts on temperature and precipitation in each model and compare to previous experiments. Our simulations will help inform future research and policy.
Hiroaki Naoe, Jorge L. García-Franco, Chang-Hyun Park, Mario Rodrigo, Froila M. Palmeiro, Federico Serva, Masakazu Taguchi, Kohei Yoshida, James A. Anstey, Javier García-Serrano, Seok-Woo Son, Yoshio Kawatani, Neal Butchart, Kevin Hamilton, Chih-Chieh Chen, Anne Glanville, Tobias Kerzenmacher, François Lott, Clara Orbe, Scott Osprey, Mijeong Park, Jadwiga H. Richter, Stefan Versick, and Shingo Watanabe
Weather Clim. Dynam., 6, 1419–1442, https://doi.org/10.5194/wcd-6-1419-2025, https://doi.org/10.5194/wcd-6-1419-2025, 2025
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Links between the stratospheric Quasi-Biennial Oscillation (QBO) and atmospheric circulations in the tropics, subtropics, and polar regions, as well as their modulation by the El Nino–Southern Oscillation, are examined through model experiments. The QBO–polar vortex connection is reproduced by a multi-model ensemble at about half the observed amplitude. Weak performance of QBO signals in these regions is likely due to unrealistically weak QBO amplitudes in the lower stratosphere.
Haruki Hirasawa, Matthew Henry, Philip J. Rasch, Robert Wood, Sarah J. Doherty, James Haywood, Alex Wong, Jean-Francois Lamarque, Ezra Brody, and Hailong Wang
EGUsphere, https://doi.org/10.5194/egusphere-2025-4810, https://doi.org/10.5194/egusphere-2025-4810, 2025
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Marine cloud brightening (MCB) is a proposal to use sea salt aerosol particles emissions to make clouds more reflective and cool the climate. Here, we use three climate models to study a hypothetical future where MCB is used to maintain 1.5C global temperatures. The models suggest that using MCB in midlatitude ocean regions can keep the climate close to present day conditions. This reduces many of the negative impacts shown in previous studies and will inform future modeling efforts.
Alistair Duffey, Walker Lee, Lauren Wheeler, Peter Irvine, Benjamin Wagman, Matthew Henry, Daniele Visioni, Michel Tsamados, and Douglas MacMartin
EGUsphere, https://doi.org/10.5194/egusphere-2025-5356, https://doi.org/10.5194/egusphere-2025-5356, 2025
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Adding a layer of tiny reflective particles high in the atmosphere is one suggested way of cooling the planet and reducing the impacts of climate change. This technique might be less logistically difficult in the high latitudes, because the material could be released at lower altitude there. Here, we use simulations in three earth system models to assess how this form of intervention, High-Latitude Low-Altitude Stratospheric Aerosol Injection (HiLLA-SAI), would impact the global climate.
Ewa M. Bednarz, Valentina Aquila, Amy H. Butler, Peter Colarco, Eric Fleming, Freja F. Østerstrøm, David Plummer, Ilaria Quaglia, William Randel, Michelle L. Santee, Takashi Sekiya, Simone Tilmes, Xinyue Wang, Shingo Watanabe, Wandi Yu, Jun Zhang, Yunqian Zhu, and Zhihong Zhuo
EGUsphere, https://doi.org/10.5194/egusphere-2025-4609, https://doi.org/10.5194/egusphere-2025-4609, 2025
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The 2022 Hunga eruption injected unprecedented quantities of water vapor into the stratosphere, alongside modest amounts of aerosol precursors. We assess its impacts on stratospheric ozone layer using a multi-model ensemble of chemistry-climate simulations. The results confirm the eruption's role in modulating SH mid and high latitudes ozone abundances in the short term, and discuss the different chemical and dynamical processes driving those changes as well as the role of natural variability.
Eliza K. Duncan, Jonathan E. Fieldsend, Alistair Sellar, Emanuele Tovazzi, Paul Kim, James M. Haywood, and Daniel G. Partridge
EGUsphere, https://doi.org/10.5194/egusphere-2025-4298, https://doi.org/10.5194/egusphere-2025-4298, 2025
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Atmospheric aerosol particles are a major confounding factor in accurately representing climate change. We build a novel generic framework to untangle the role of complex processes focusing on a remote site in Antarctica as a case study in near-pristine conditions. Our machine-learning model predicts aerosol concentrations from an airmass history, considering the meteorology and potential sources and removal processes, enabling improved representation in climate models.
George Jordan, Florent Malavelle, Jim Haywood, Ying Chen, Ben Johnson, Daniel Partridge, Amy Peace, Eliza Duncan, Duncan Watson-Parris, David Neubauer, Anton Laakso, Martine Michou, and Pierre Nabat
Atmos. Chem. Phys., 25, 13393–13428, https://doi.org/10.5194/acp-25-13393-2025, https://doi.org/10.5194/acp-25-13393-2025, 2025
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The 2014–15 Holuhraun eruption created a vast aerosol plume that acted as a natural experiment to assess how well climate models capture changes in cloud properties due to increased aerosol. We find that climate models represent the observed shift to smaller, more numerous cloud droplets well. However, climate models diverge in their aerosol-induced changes to large-scale cloud properties, particularly cloud liquid water content. Our study shows that Holuhraun had a cooling effect on the Earth.
Zhihong Zhuo, Xinyue Wang, Yunqian Zhu, Wandi Yu, Ewa M. Bednarz, Eric Fleming, Peter R. Colarco, Shingo Watanabe, David Plummer, Georgiy Stenchikov, William Randel, Adam Bourassa, Valentina Aquila, Takashi Sekiya, Mark R. Schoeberl, Simone Tilmes, Jun Zhang, Paul J. Kushner, and Francesco S. R. Pausata
Atmos. Chem. Phys., 25, 13161–13176, https://doi.org/10.5194/acp-25-13161-2025, https://doi.org/10.5194/acp-25-13161-2025, 2025
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The 2022 Hunga eruption caused unprecedented stratospheric water injection, triggering unique atmospheric impacts. This study combines observations and model simulations, projecting a stratospheric water vapor anomaly lasting 4–7 years, with significant temperature variations and ozone depletion in the upper atmosphere lasting 7–10 years. These findings offer critical insights into the role of stratospheric water vapor in shaping climate and atmospheric chemistry.
Isobel M. Parry, Paul D. L. Ritchie, Olivier Boucher, Peter M. Cox, James M. Haywood, Ulrike Niemeier, Roland Séférian, Simone Tilmes, and Daniele Visioni
EGUsphere, https://doi.org/10.5194/egusphere-2025-4889, https://doi.org/10.5194/egusphere-2025-4889, 2025
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Stratospheric aerosol injection (SAI) aims to counteract global warming by injecting aerosols into the stratosphere, thereby increasing the reflection of incoming sunlight. Despite concerns that SAI could reduce vegetation productivity by reducing the amount of sunlight at the Earth's surface and shifting rainfall patterns, SAI simulations project an increase in land carbon storage globally and in the Amazon compared to a moderate warming scenario, primarily due to increased CO2 fertilisation.
Yoshio Kawatani, Kevin Hamilton, Shingo Watanabe, Masakazu Taguchi, Federico Serva, James A. Anstey, Jadwiga H. Richter, Neal Butchart, Clara Orbe, Scott M. Osprey, Hiroaki Naoe, Dillon Elsbury, Chih-Chieh Chen, Javier García-Serrano, Anne Glanville, Tobias Kerzenmacher, François Lott, Froila M. Palmeiro, Mijeong Park, Stefan Versick, and Kohei Yoshida
Weather Clim. Dynam., 6, 1045–1073, https://doi.org/10.5194/wcd-6-1045-2025, https://doi.org/10.5194/wcd-6-1045-2025, 2025
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The Quasi-Biennial Oscillation (QBO) of the tropical stratospheric mean winds has been relatively steady over the 7 decades it has been observed, but there are always cycle-to-cycle variations. This study used several global atmospheric models to investigate systematic modulation of the QBO by the El Niño/La Niña cycle. All models simulated shorter periods during El Niño, in agreement with observations. By contrast, the models disagreed even on the sign of the El Niño effect on QBO amplitude.
Raina Roy, Julie M. Arblaster, Matthew C. Wheeler, Eun-Pa Lim, and Jadwiga H. Richter
EGUsphere, https://doi.org/10.5194/egusphere-2025-4453, https://doi.org/10.5194/egusphere-2025-4453, 2025
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A key pattern of tropical weather, the Madden-Julian Oscillation, has become significantly harder to predict since the late 1990s. We discovered this by comparing forecasts from major models across two time periods. The decrease in forecast skill is linked to changes in large-scale climate patterns, not just model errors. This means to improve long-range weather forecasts, models must better simulate how these large-scale patterns interact with tropical weather.
Ilaria Quaglia, Daniele Visioni, Ewa M. Bednarz, Yunqian Zhu, Georgiy Stenchikov, Valentina Aquila, Cheng-Cheng Liu, Graham W. Mann, Yifeng Peng, Takashi Sekiya, Simone Tilmes, Xinyue Wang, Shingo Watanabe, Pengfei Yu, Jun Zhang, and Wandi Yu
EGUsphere, https://doi.org/10.5194/egusphere-2025-3769, https://doi.org/10.5194/egusphere-2025-3769, 2025
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On January 15, 2022, the Hunga volcano eruption released unprecedented amounts of water vapor into the atmosphere alongside a modest amount of SO2. In this work we analyse results from multiple Earth system models. The models agree that the eruption led to small negative radiative forcing from sulfate aerosols and that the contribution from water vapor was minimal. Therefore, the Hunga eruption cannot explain the exceptional surface warming observed in 2023.
Yunqian Zhu, Hideharu Akiyoshi, Valentina Aquila, Elizabeth Asher, Ewa M. Bednarz, Slimane Bekki, Christoph Brühl, Amy H. Butler, Parker Case, Simon Chabrillat, Gabriel Chiodo, Margot Clyne, Peter R. Colarco, Sandip Dhomse, Lola Falletti, Eric Fleming, Ben Johnson, Andrin Jörimann, Mahesh Kovilakam, Gerbrand Koren, Ales Kuchar, Nicolas Lebas, Qing Liang, Cheng-Cheng Liu, Graham Mann, Michael Manyin, Marion Marchand, Olaf Morgenstern, Paul Newman, Luke D. Oman, Freja F. Østerstrøm, Yifeng Peng, David Plummer, Ilaria Quaglia, William Randel, Samuel Rémy, Takashi Sekiya, Stephen Steenrod, Timofei Sukhodolov, Simone Tilmes, Kostas Tsigaridis, Rei Ueyama, Daniele Visioni, Xinyue Wang, Shingo Watanabe, Yousuke Yamashita, Pengfei Yu, Wandi Yu, Jun Zhang, and Zhihong Zhuo
Geosci. Model Dev., 18, 5487–5512, https://doi.org/10.5194/gmd-18-5487-2025, https://doi.org/10.5194/gmd-18-5487-2025, 2025
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To understand the climate impact of the 2022 Hunga volcanic eruption, we developed a climate model–observation comparison project. The paper describes the protocols and models that participate in the experiments. We designed several experiments to achieve our goals of this activity: (1) to evaluate the climate model performance and (2) to understand the Earth system responses to this eruption.
Jinbo Xie, Qi Tang, Michael Prather, Jadwiga Richter, and Shixuan Zhang
Atmos. Chem. Phys., 25, 9315–9333, https://doi.org/10.5194/acp-25-9315-2025, https://doi.org/10.5194/acp-25-9315-2025, 2025
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Analysis of the interaction between the climate and ozone in the stratosphere is complicated by the inability of climate models to simulate the quasi-biennial oscillation (QBO) – an important climate mode in the stratosphere. We use a set of model simulations that realistically simulate QBO and a novel ozone diagnostic tool to separate temperature- and circulation-driven QBO impacts. These are important for diagnosing model–model differences in QBO–ozone responses for climate projections.
Elizabeth Quaye, Ben T. Johnson, James M. Haywood, Guido R. van der Werf, Roland Vernooij, Stephen A. Sitch, and Tom Eames
EGUsphere, https://doi.org/10.5194/egusphere-2025-3936, https://doi.org/10.5194/egusphere-2025-3936, 2025
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We find aerosol optical depths in a global climate model are overestimated during extreme wildfire events if emissions are scaled up by a factor of two, typically applied to improve simulated aerosol on seasonal–annual timescales. We propose a technique where a variable scaling factor is determined by fuel consumption, improving correlation in five fire-affected areas. We explore the impact of this change on aerosol radiative effects, during extreme events and on broader space and time scales.
Ezra Brody, Yan Zhang, Douglas G. MacMartin, Daniele Visioni, Ben Kravitz, and Ewa M. Bednarz
Earth Syst. Dynam., 16, 1325–1341, https://doi.org/10.5194/esd-16-1325-2025, https://doi.org/10.5194/esd-16-1325-2025, 2025
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Stratospheric aerosol injection (SAI) is being studied as a possible supplement to emission reduction to temporarily mitigate some of the risks associated with climate change. The latitudes at which SAI is done determine the effect on the climate. We try to find if there are combinations of latitudes that do a better job of counteracting climate change than existing strategies. We found that there are, but just how significant these improvements are depends on the amount of cooling.
Lantao Sun, James W. Hurrell, Kristen L. Rasmussen, Bali Summers, Erin A. Sherman, and Ben Kravitz
EGUsphere, https://doi.org/10.5194/egusphere-2025-3490, https://doi.org/10.5194/egusphere-2025-3490, 2025
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We develop a novel framework using the convection-permitting Weather Research and Forecasting (WRF) model to assess how stratospheric aerosol injection, a solar climate intervention strategy, affects future convective weather over the contiguous U.S. Results demonstrate the feasibility and scientific potential of this approach for evaluating weather-scale impacts and suggest that such intervention may mitigate changes in temperature, precipitation, and convective activity due to warming.
Masaru Yoshioka, Daniel P. Grosvenor, Amy H. Peace, Jim M. Haywood, Ying Chen, and Paul R. Field
EGUsphere, https://doi.org/10.5194/egusphere-2025-3244, https://doi.org/10.5194/egusphere-2025-3244, 2025
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We used advanced computer simulations to study how aerosol particles from a volcanic eruption in Iceland affected clouds. The eruption plume increased small droplets, but changes in cloud water and horizontal extent were not clear. Satellite comparisons between plume and non-plume regions can miss volcanic effects due to spatial variability in weather and aerosol, but simulations can isolate the impact by comparing cases with and without the eruption.
Simone Tilmes, Ewa M. Bednarz, Andrin Jörimann, Daniele Visioni, Douglas E. Kinnison, Gabriel Chiodo, and David Plummer
Atmos. Chem. Phys., 25, 6001–6023, https://doi.org/10.5194/acp-25-6001-2025, https://doi.org/10.5194/acp-25-6001-2025, 2025
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In this paper, we describe the details of a new multi-model intercomparison experiment to assess the effects of Stratospheric Aerosol Intervention (SAI) on stratospheric chemistry and dynamics and, therefore, ozone. Second, we discuss the advantages and differences of the more constrained experiment compared to fully interactive model experiments. This way, we advance the process-level understanding of the drivers of SAI-induced atmospheric responses.
Martin Juckes, Karl E. Taylor, Fabrizio Antonio, David Brayshaw, Carlo Buontempo, Jian Cao, Paul J. Durack, Michio Kawamiya, Hyungjun Kim, Tomas Lovato, Chloe Mackallah, Matthew Mizielinski, Alessandra Nuzzo, Martina Stockhause, Daniele Visioni, Jeremy Walton, Briony Turner, Eleanor O'Rourke, and Beth Dingley
Geosci. Model Dev., 18, 2639–2663, https://doi.org/10.5194/gmd-18-2639-2025, https://doi.org/10.5194/gmd-18-2639-2025, 2025
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The Baseline Climate Variables for Earth System Modelling (ESM-BCVs) are defined as a list of 135 variables which have high utility for the evaluation and exploitation of climate simulations. The list reflects the most frequently used variables from Earth system models based on an assessment of data publication and download records from the largest archive of global climate projects.
Lena Feld, Pablo Schmid, Marios Mermigkas, Dimitrios Balis, Jochen Gross, Darko Dubravica, Carlos Alberti, Benedikt Herkommer, Stefan Versick, Roland Ruhnke, Frank Hase, and Peter Braesicke
EGUsphere, https://doi.org/10.5194/egusphere-2025-639, https://doi.org/10.5194/egusphere-2025-639, 2025
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Our goal is to measure CO2 emissions from cities, to verify and improve our knowledge of reported anthropogenic emissions. We use atmospheric measurements and simulations of CO2 transport to find an independent estimate. This study investigates the CO2 emissions of the city of Thessaloniki, where the reported emissions differ. The data we collected indicates that the emissions are larger than stated by the ODIAC inventory, which we used for our simulations.
Mari R. Tye, Ming Ge, Jadwiga H. Richter, Ethan D. Gutmann, Allyson Rugg, Cindy L. Bruyère, Sue Ellen Haupt, Flavio Lehner, Rachel McCrary, Andrew J. Newman, and Andy Wood
Hydrol. Earth Syst. Sci., 29, 1117–1133, https://doi.org/10.5194/hess-29-1117-2025, https://doi.org/10.5194/hess-29-1117-2025, 2025
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There is a perceived mismatch between the spatial scales on which global climate models can produce data and those needed for water management decisions. However, poor communication of specific metrics relevant to local decisions is also a problem. We assessed the credibility of a set of water management decision metrics in the Community Earth System Model v2 (CESM2). CESM2 shows potentially greater use of its output in long-range water management decisions.
Chaim I. Garfinkel, Zachary D. Lawrence, Amy H. Butler, Etienne Dunn-Sigouin, Irene Erner, Alexey Y. Karpechko, Gerbrand Koren, Marta Abalos, Blanca Ayarzagüena, David Barriopedro, Natalia Calvo, Alvaro de la Cámara, Andrew Charlton-Perez, Judah Cohen, Daniela I. V. Domeisen, Javier García-Serrano, Neil P. Hindley, Martin Jucker, Hera Kim, Robert W. Lee, Simon H. Lee, Marisol Osman, Froila M. Palmeiro, Inna Polichtchouk, Jian Rao, Jadwiga H. Richter, Chen Schwartz, Seok-Woo Son, Masakazu Taguchi, Nicholas L. Tyrrell, Corwin J. Wright, and Rachel W.-Y. Wu
Weather Clim. Dynam., 6, 171–195, https://doi.org/10.5194/wcd-6-171-2025, https://doi.org/10.5194/wcd-6-171-2025, 2025
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Variability in the extratropical stratosphere and troposphere is coupled, and because of the longer timescales characteristic of the stratosphere, this allows for a window of opportunity for surface prediction. This paper assesses whether models used for operational prediction capture these coupling processes accurately. We find that most processes are too weak; however downward coupling from the lower stratosphere to the near surface is too strong.
Tatiana Klimiuk, Patrick Ludwig, Antonio Sanchez-Benitez, Helge F. Goessling, Peter Braesicke, and Joaquim G. Pinto
Earth Syst. Dynam., 16, 239–255, https://doi.org/10.5194/esd-16-239-2025, https://doi.org/10.5194/esd-16-239-2025, 2025
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Our study examines potential changes in heatwaves in central Europe due to global warming, using the 2019 summer heatwave as an example. By producing high-resolution storylines, we provide insights into how future heatwaves might spread, how they might persist for longer, and where stronger or weaker temperature increases may occur. This research helps us understand regional thermodynamic responses and highlights the importance of local strategies to protect communities from future heat events.
Matthew Henry, Ewa M. Bednarz, and Jim Haywood
Atmos. Chem. Phys., 24, 13253–13268, https://doi.org/10.5194/acp-24-13253-2024, https://doi.org/10.5194/acp-24-13253-2024, 2024
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Stratospheric aerosol injection (SAI) refers to a climate intervention by which aerosols are intentionally added to the high atmosphere to increase the amount of reflected sunlight and reduce Earth's temperature. The climate outcomes of SAI depend on the latitude of injection. While injecting aerosols at the Equator has undesirable side effects, injecting away from the Equator has different effects on temperature, rainfall, ozone, and atmospheric circulation, which are analysed in this work.
Ilaria Quaglia and Daniele Visioni
Earth Syst. Dynam., 15, 1527–1541, https://doi.org/10.5194/esd-15-1527-2024, https://doi.org/10.5194/esd-15-1527-2024, 2024
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On 1 January 2020, international shipping vessels were required to substantially reduce the amount of particulate they emit to improve air quality. In this work we demonstrate how this regulatory change contributed to the anomalous warming observed in recent months using climate model simulations that include such a change. Future policies should also perhaps consider their impact on climate, and climate modelers should promptly include those changes in future modeling efforts.
Ou Wang, Ju Liang, Yuchen Gu, Jim M. Haywood, Ying Chen, Chenwei Fang, and Qin'geng Wang
Atmos. Chem. Phys., 24, 12355–12373, https://doi.org/10.5194/acp-24-12355-2024, https://doi.org/10.5194/acp-24-12355-2024, 2024
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As extreme precipitation events increase in China, this study explores the potential of stratospheric aerosol injection (SAI) to mitigate these effects by the end of the 21st century using the UKESM1 model. Results show that SAI reduces extreme precipitation in eastern China. However, caution is advised due to potential side effects in high-latitude regions, and further optimization is required for future SAI deployment.
Philip J. Rasch, Haruki Hirasawa, Mingxuan Wu, Sarah J. Doherty, Robert Wood, Hailong Wang, Andy Jones, James Haywood, and Hansi Singh
Geosci. Model Dev., 17, 7963–7994, https://doi.org/10.5194/gmd-17-7963-2024, https://doi.org/10.5194/gmd-17-7963-2024, 2024
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We introduce a protocol to compare computer climate simulations to better understand a proposed strategy intended to counter warming and climate impacts from greenhouse gas increases. This slightly changes clouds in six ocean regions to reflect more sunlight and cool the Earth. Example changes in clouds and climate are shown for three climate models. Cloud changes differ between the models, but precipitation and surface temperature changes are similar when their cooling effects are made similar.
Amy H. Peace, Ying Chen, George Jordan, Daniel G. Partridge, Florent Malavelle, Eliza Duncan, and Jim M. Haywood
Atmos. Chem. Phys., 24, 9533–9553, https://doi.org/10.5194/acp-24-9533-2024, https://doi.org/10.5194/acp-24-9533-2024, 2024
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Natural aerosols from volcanic eruptions can help us understand how anthropogenic aerosols modify climate. We use observations and model simulations of the 2014–2015 Holuhraun eruption plume to examine aerosol–cloud interactions in September 2014. We find a shift to clouds with smaller, more numerous cloud droplets in the first 2 weeks of the eruption. In the third week, the background meteorology and previous conditions experienced by air masses modulate the aerosol perturbation to clouds.
Christina V. Brodowsky, Timofei Sukhodolov, Gabriel Chiodo, Valentina Aquila, Slimane Bekki, Sandip S. Dhomse, Michael Höpfner, Anton Laakso, Graham W. Mann, Ulrike Niemeier, Giovanni Pitari, Ilaria Quaglia, Eugene Rozanov, Anja Schmidt, Takashi Sekiya, Simone Tilmes, Claudia Timmreck, Sandro Vattioni, Daniele Visioni, Pengfei Yu, Yunqian Zhu, and Thomas Peter
Atmos. Chem. Phys., 24, 5513–5548, https://doi.org/10.5194/acp-24-5513-2024, https://doi.org/10.5194/acp-24-5513-2024, 2024
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The aerosol layer is an essential part of the climate system. We characterize the sulfur budget in a volcanically quiescent (background) setting, with a special focus on the sulfate aerosol layer using, for the first time, a multi-model approach. The aim is to identify weak points in the representation of the atmospheric sulfur budget in an intercomparison of nine state-of-the-art coupled global circulation models.
Anton Laakso, Daniele Visioni, Ulrike Niemeier, Simone Tilmes, and Harri Kokkola
Earth Syst. Dynam., 15, 405–427, https://doi.org/10.5194/esd-15-405-2024, https://doi.org/10.5194/esd-15-405-2024, 2024
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This study is the second in a two-part series in which we explore the dependency of the impacts of stratospheric sulfur injections on both the model employed and the strategy of injection utilized. The study uncovers uncertainties associated with these techniques to cool climate, highlighting how the simulated climate impacts are dependent on both the selected model and the magnitude of the injections. We also show that estimating precipitation impacts of aerosol injection is a complex task.
Daniele Visioni, Alan Robock, Jim Haywood, Matthew Henry, Simone Tilmes, Douglas G. MacMartin, Ben Kravitz, Sarah J. Doherty, John Moore, Chris Lennard, Shingo Watanabe, Helene Muri, Ulrike Niemeier, Olivier Boucher, Abu Syed, Temitope S. Egbebiyi, Roland Séférian, and Ilaria Quaglia
Geosci. Model Dev., 17, 2583–2596, https://doi.org/10.5194/gmd-17-2583-2024, https://doi.org/10.5194/gmd-17-2583-2024, 2024
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This paper describes a new experimental protocol for the Geoengineering Model Intercomparison Project (GeoMIP). In it, we describe the details of a new simulation of sunlight reflection using the stratospheric aerosols that climate models are supposed to run, and we explain the reasons behind each choice we made when defining the protocol.
Yan Zhang, Douglas G. MacMartin, Daniele Visioni, Ewa M. Bednarz, and Ben Kravitz
Earth Syst. Dynam., 15, 191–213, https://doi.org/10.5194/esd-15-191-2024, https://doi.org/10.5194/esd-15-191-2024, 2024
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Injecting SO2 into the lower stratosphere can temporarily reduce global mean temperature and mitigate some risks associated with climate change, but injecting it at different latitudes and seasons would have different impacts. This study introduces new stratospheric aerosol injection (SAI) strategies and explores the importance of the choice of SAI strategy, demonstrating that it notably affects the distribution of aerosol cloud, injection efficiency, and various surface climate impacts.
George Jordan, Florent Malavelle, Ying Chen, Amy Peace, Eliza Duncan, Daniel G. Partridge, Paul Kim, Duncan Watson-Parris, Toshihiko Takemura, David Neubauer, Gunnar Myhre, Ragnhild Skeie, Anton Laakso, and James Haywood
Atmos. Chem. Phys., 24, 1939–1960, https://doi.org/10.5194/acp-24-1939-2024, https://doi.org/10.5194/acp-24-1939-2024, 2024
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The 2014–15 Holuhraun eruption caused a huge aerosol plume in an otherwise unpolluted region, providing a chance to study how aerosol alters cloud properties. This two-part study uses observations and models to quantify this relationship’s impact on the Earth’s energy budget. Part 1 suggests the models capture the observed spatial and chemical evolution of the plume, yet no model plume is exact. Understanding these differences is key for Part 2, where changes to cloud properties are explored.
Jim M. Haywood, Andy Jones, Anthony C. Jones, Paul Halloran, and Philip J. Rasch
Atmos. Chem. Phys., 23, 15305–15324, https://doi.org/10.5194/acp-23-15305-2023, https://doi.org/10.5194/acp-23-15305-2023, 2023
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The difficulties in ameliorating global warming and the associated climate change via conventional mitigation are well documented, with all climate model scenarios exceeding 1.5 °C above the preindustrial level in the near future. There is therefore a growing interest in geoengineering to reflect a greater proportion of sunlight back to space and offset some of the global warming. We use a state-of-the-art Earth-system model to investigate two of the most prominent geoengineering strategies.
Calvin Howes, Pablo E. Saide, Hugh Coe, Amie Dobracki, Steffen Freitag, Jim M. Haywood, Steven G. Howell, Siddhant Gupta, Janek Uin, Mary Kacarab, Chongai Kuang, L. Ruby Leung, Athanasios Nenes, Greg M. McFarquhar, James Podolske, Jens Redemann, Arthur J. Sedlacek, Kenneth L. Thornhill, Jenny P. S. Wong, Robert Wood, Huihui Wu, Yang Zhang, Jianhao Zhang, and Paquita Zuidema
Atmos. Chem. Phys., 23, 13911–13940, https://doi.org/10.5194/acp-23-13911-2023, https://doi.org/10.5194/acp-23-13911-2023, 2023
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To better understand smoke properties and its interactions with clouds, we compare the WRF-CAM5 model with observations from ORACLES, CLARIFY, and LASIC field campaigns in the southeastern Atlantic in August 2017. The model transports and mixes smoke well but does not fully capture some important processes. These include smoke chemical and physical aging over 4–12 days, smoke removal by rain, sulfate particle formation, aerosol activation into cloud droplets, and boundary layer turbulence.
Ewa M. Bednarz, Amy H. Butler, Daniele Visioni, Yan Zhang, Ben Kravitz, and Douglas G. MacMartin
Atmos. Chem. Phys., 23, 13665–13684, https://doi.org/10.5194/acp-23-13665-2023, https://doi.org/10.5194/acp-23-13665-2023, 2023
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We use a state-of-the-art Earth system model and a set of stratospheric aerosol injection (SAI) strategies to achieve the same level of global mean surface cooling through different combinations of location and/or timing of the injection. We demonstrate that the choice of SAI strategy can lead to contrasting impacts on stratospheric and tropospheric temperatures, circulation, and chemistry (including stratospheric ozone), thereby leading to different impacts on regional surface climate.
Ewa M. Bednarz, Ryan Hossaini, and Martyn P. Chipperfield
Atmos. Chem. Phys., 23, 13701–13711, https://doi.org/10.5194/acp-23-13701-2023, https://doi.org/10.5194/acp-23-13701-2023, 2023
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We quantify, for the first time, the time-varying impact of uncontrolled emissions of chlorinated very short-lived substances (Cl-VSLSs) on stratospheric ozone using a state-of-the-art chemistry-climate model. We demonstrate that Cl-VSLSs already have a non-negligible impact on stratospheric ozone, including a local reduction of up to ~7 DU in Arctic ozone in the cold winter of 2019/20, and any so future growth in emissions will continue to offset some of the benefits of the Montreal Protocol.
Ewa M. Bednarz, Ryan Hossaini, N. Luke Abraham, and Martyn P. Chipperfield
Geosci. Model Dev., 16, 6187–6209, https://doi.org/10.5194/gmd-16-6187-2023, https://doi.org/10.5194/gmd-16-6187-2023, 2023
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Development and performance of the new DEST chemistry scheme of UM–UKCA is described. The scheme extends the standard StratTrop scheme by including important updates to the halogen chemistry, thus allowing process-oriented studies of stratospheric ozone depletion and recovery, including impacts from both controlled long-lived ozone-depleting substances and emerging issues around uncontrolled, very short-lived substances. It will thus aid studies in support of future ozone assessment reports.
Matthew Henry, Jim Haywood, Andy Jones, Mohit Dalvi, Alice Wells, Daniele Visioni, Ewa M. Bednarz, Douglas G. MacMartin, Walker Lee, and Mari R. Tye
Atmos. Chem. Phys., 23, 13369–13385, https://doi.org/10.5194/acp-23-13369-2023, https://doi.org/10.5194/acp-23-13369-2023, 2023
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Solar climate interventions, such as injecting sulfur in the stratosphere, may be used to offset some of the adverse impacts of global warming. We use two independently developed Earth system models to assess the uncertainties around stratospheric sulfur injections. The injection locations and amounts are optimized to maintain the same pattern of surface temperature. While both models show reduced warming, the change in rainfall patterns (even without sulfur injections) is uncertain.
Monali Borthakur, Miriam Sinnhuber, Alexandra Laeng, Thomas Reddmann, Peter Braesicke, Gabriele Stiller, Thomas von Clarmann, Bernd Funke, Ilya Usoskin, Jan Maik Wissing, and Olesya Yakovchuk
Atmos. Chem. Phys., 23, 12985–13013, https://doi.org/10.5194/acp-23-12985-2023, https://doi.org/10.5194/acp-23-12985-2023, 2023
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Reduced ozone levels resulting from ozone depletion mean more exposure to UV radiation, which has various effects on human health. We analysed solar events to see what influence it has on the chemistry of Earth's atmosphere and how this atmospheric chemistry change can affect the ozone. To do this, we used an atmospheric model considering only chemistry and compared it with satellite data. The focus was mainly on the contribution of chlorine, and we found about 10 %–20 % ozone loss due to that.
Chenwei Fang, Jim M. Haywood, Ju Liang, Ben T. Johnson, Ying Chen, and Bin Zhu
Atmos. Chem. Phys., 23, 8341–8368, https://doi.org/10.5194/acp-23-8341-2023, https://doi.org/10.5194/acp-23-8341-2023, 2023
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The responses of Asian summer monsoon duration and intensity to air pollution mitigation are identified given the net-zero future. We show that reducing scattering aerosols makes the rainy season longer and stronger across South Asia and East Asia but that absorbing aerosol reduction has the opposite effect. Our results hint at distinct monsoon responses to emission controls that target different aerosols.
Christian Scharun, Roland Ruhnke, and Peter Braesicke
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2023-91, https://doi.org/10.5194/gmd-2023-91, 2023
Publication in GMD not foreseen
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The identification and quantification of greenhouse gas (GHG) emissions is an important task for monitoring mitigation strategies under climate change. With RICHARD 1.0, we developed a novel approach using spatiotemporal proxy data and a selection algorithm to detect GHG emission hotspots. By using a one year dataset of global climate model output we showed that RICHARD is able to determine and quantify the source strengths of GHG emission hotspots much more precisely than conventional methods.
Daniele Visioni, Ben Kravitz, Alan Robock, Simone Tilmes, Jim Haywood, Olivier Boucher, Mark Lawrence, Peter Irvine, Ulrike Niemeier, Lili Xia, Gabriel Chiodo, Chris Lennard, Shingo Watanabe, John C. Moore, and Helene Muri
Atmos. Chem. Phys., 23, 5149–5176, https://doi.org/10.5194/acp-23-5149-2023, https://doi.org/10.5194/acp-23-5149-2023, 2023
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Geoengineering indicates methods aiming to reduce the temperature of the planet by means of reflecting back a part of the incoming radiation before it reaches the surface or allowing more of the planetary radiation to escape into space. It aims to produce modelling experiments that are easy to reproduce and compare with different climate models, in order to understand the potential impacts of these techniques. Here we assess its past successes and failures and talk about its future.
Alice F. Wells, Andy Jones, Martin Osborne, Lilly Damany-Pearce, Daniel G. Partridge, and James M. Haywood
Atmos. Chem. Phys., 23, 3985–4007, https://doi.org/10.5194/acp-23-3985-2023, https://doi.org/10.5194/acp-23-3985-2023, 2023
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In 2019 the Raikoke volcano erupted explosively, emitting the largest injection of SO2 into the stratosphere since 2011. Observations indicated that a large amount of volcanic ash was also injected. Previous studies have identified that volcanic ash can prolong the lifetime of stratospheric aerosol optical depth, which we explore in UKESM1. Comparisons to observations suggest that including ash in model emission schemes can improve the representation of volcanic plumes in global climate models.
Khalil Karami, Rolando Garcia, Christoph Jacobi, Jadwiga H. Richter, and Simone Tilmes
Atmos. Chem. Phys., 23, 3799–3818, https://doi.org/10.5194/acp-23-3799-2023, https://doi.org/10.5194/acp-23-3799-2023, 2023
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Alongside mitigation and adaptation efforts, stratospheric aerosol intervention (SAI) is increasingly considered a third pillar to combat dangerous climate change. We investigate the teleconnection between the quasi-biennial oscillation in the equatorial stratosphere and the Arctic stratospheric polar vortex under a warmer climate and an SAI scenario. We show that the Holton–Tan relationship weakens under both scenarios and discuss the physical mechanisms responsible for such changes.
Eric Förster, Harald Bönisch, Marco Neumaier, Florian Obersteiner, Andreas Zahn, Andreas Hilboll, Anna B. Kalisz Hedegaard, Nikos Daskalakis, Alexandros Panagiotis Poulidis, Mihalis Vrekoussis, Michael Lichtenstern, and Peter Braesicke
Atmos. Chem. Phys., 23, 1893–1918, https://doi.org/10.5194/acp-23-1893-2023, https://doi.org/10.5194/acp-23-1893-2023, 2023
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The airborne megacity campaign EMeRGe provided an unprecedented amount of trace gas measurements. We combine measured volatile organic compounds (VOCs) with trajectory-modelled emission uptakes to identify potential source regions of pollution. We also characterise the chemical fingerprints (e.g. biomass burning and anthropogenic signatures) of the probed air masses to corroborate the contributing source regions. Our approach is the first large-scale study of VOCs originating from megacities.
Ju Liang and Jim Haywood
Atmos. Chem. Phys., 23, 1687–1703, https://doi.org/10.5194/acp-23-1687-2023, https://doi.org/10.5194/acp-23-1687-2023, 2023
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The recent record-breaking flood events in China during the summer of 2021 highlight the importance of mitigating the risks from future changes in high-impact weather systems under global warming. Based on a state-of-the-art Earth system model, we demonstrate a pilot study on the responses of atmospheric rivers and extreme precipitation over East Asia to anthropogenically induced climate warming and an unconventional mitigation strategy – stratospheric aerosol injection.
Yangxin Chen, Duoying Ji, Qian Zhang, John C. Moore, Olivier Boucher, Andy Jones, Thibaut Lurton, Michael J. Mills, Ulrike Niemeier, Roland Séférian, and Simone Tilmes
Earth Syst. Dynam., 14, 55–79, https://doi.org/10.5194/esd-14-55-2023, https://doi.org/10.5194/esd-14-55-2023, 2023
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Solar geoengineering has been proposed as a way of counteracting the warming effects of increasing greenhouse gases by reflecting solar radiation. This work shows that solar geoengineering can slow down the northern-high-latitude permafrost degradation but cannot preserve the permafrost ecosystem as that under a climate of the same warming level without solar geoengineering.
Ilaria Quaglia, Claudia Timmreck, Ulrike Niemeier, Daniele Visioni, Giovanni Pitari, Christina Brodowsky, Christoph Brühl, Sandip S. Dhomse, Henning Franke, Anton Laakso, Graham W. Mann, Eugene Rozanov, and Timofei Sukhodolov
Atmos. Chem. Phys., 23, 921–948, https://doi.org/10.5194/acp-23-921-2023, https://doi.org/10.5194/acp-23-921-2023, 2023
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The last very large explosive volcanic eruption we have measurements for is the eruption of Mt. Pinatubo in 1991. It is therefore often used as a benchmark for climate models' ability to reproduce these kinds of events. Here, we compare available measurements with the results from multiple experiments conducted with climate models interactively simulating the aerosol cloud formation.
Daniele Visioni, Ewa M. Bednarz, Walker R. Lee, Ben Kravitz, Andy Jones, Jim M. Haywood, and Douglas G. MacMartin
Atmos. Chem. Phys., 23, 663–685, https://doi.org/10.5194/acp-23-663-2023, https://doi.org/10.5194/acp-23-663-2023, 2023
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The paper constitutes Part 1 of a study performing a first systematic inter-model comparison of the atmospheric responses to stratospheric sulfate aerosol injections (SAIs) at various latitudes as simulated by three state-of-the-art Earth system models. We identify similarities and differences in the modeled aerosol burden, investigate the differences in the aerosol approaches between the models, and ultimately show the differences produced in surface climate, temperature and precipitation.
John T. Fasullo and Jadwiga H. Richter
Atmos. Chem. Phys., 23, 163–182, https://doi.org/10.5194/acp-23-163-2023, https://doi.org/10.5194/acp-23-163-2023, 2023
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The continued high levels of anthropogenic greenhouse gas emissions increase the likelihood that key climate warming thresholds will be exceeded in the coming decades. Here we examine a recently proposed geoengineering approach using two recently produced climate model experiments. We find the associated latitudinal distribution of aerosol mass to exhibit substantial uncertainty, suggesting the need for significant flexibility in the location and amount of aerosol delivery, if implemented.
Jadwiga H. Richter, Daniele Visioni, Douglas G. MacMartin, David A. Bailey, Nan Rosenbloom, Brian Dobbins, Walker R. Lee, Mari Tye, and Jean-Francois Lamarque
Geosci. Model Dev., 15, 8221–8243, https://doi.org/10.5194/gmd-15-8221-2022, https://doi.org/10.5194/gmd-15-8221-2022, 2022
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Solar climate intervention using stratospheric aerosol injection is a proposed method of reducing global mean temperatures to reduce the worst consequences of climate change. We present a new modeling protocol aimed at simulating a plausible deployment of stratospheric aerosol injection and reproducibility of simulations using other Earth system models: Assessing Responses and Impacts of Solar climate intervention on the Earth system with stratospheric aerosol injection (ARISE-SAI).
Paul A. Barrett, Steven J. Abel, Hugh Coe, Ian Crawford, Amie Dobracki, James Haywood, Steve Howell, Anthony Jones, Justin Langridge, Greg M. McFarquhar, Graeme J. Nott, Hannah Price, Jens Redemann, Yohei Shinozuka, Kate Szpek, Jonathan W. Taylor, Robert Wood, Huihui Wu, Paquita Zuidema, Stéphane Bauguitte, Ryan Bennett, Keith Bower, Hong Chen, Sabrina Cochrane, Michael Cotterell, Nicholas Davies, David Delene, Connor Flynn, Andrew Freedman, Steffen Freitag, Siddhant Gupta, David Noone, Timothy B. Onasch, James Podolske, Michael R. Poellot, Sebastian Schmidt, Stephen Springston, Arthur J. Sedlacek III, Jamie Trembath, Alan Vance, Maria A. Zawadowicz, and Jianhao Zhang
Atmos. Meas. Tech., 15, 6329–6371, https://doi.org/10.5194/amt-15-6329-2022, https://doi.org/10.5194/amt-15-6329-2022, 2022
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To better understand weather and climate, it is vital to go into the field and collect observations. Often measurements take place in isolation, but here we compared data from two aircraft and one ground-based site. This was done in order to understand how well measurements made on one platform compared to those made on another. Whilst this is easy to do in a controlled laboratory setting, it is more challenging in the real world, and so these comparisons are as valuable as they are rare.
Flossie Brown, Gerd A. Folberth, Stephen Sitch, Susanne Bauer, Marijn Bauters, Pascal Boeckx, Alexander W. Cheesman, Makoto Deushi, Inês Dos Santos Vieira, Corinne Galy-Lacaux, James Haywood, James Keeble, Lina M. Mercado, Fiona M. O'Connor, Naga Oshima, Kostas Tsigaridis, and Hans Verbeeck
Atmos. Chem. Phys., 22, 12331–12352, https://doi.org/10.5194/acp-22-12331-2022, https://doi.org/10.5194/acp-22-12331-2022, 2022
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Surface ozone can decrease plant productivity and impair human health. In this study, we evaluate the change in surface ozone due to climate change over South America and Africa using Earth system models. We find that if the climate were to change according to the worst-case scenario used here, models predict that forested areas in biomass burning locations and urban populations will be at increasing risk of ozone exposure, but other areas will experience a climate benefit.
Stephen G. Yeager, Nan Rosenbloom, Anne A. Glanville, Xian Wu, Isla Simpson, Hui Li, Maria J. Molina, Kristen Krumhardt, Samuel Mogen, Keith Lindsay, Danica Lombardozzi, Will Wieder, Who M. Kim, Jadwiga H. Richter, Matthew Long, Gokhan Danabasoglu, David Bailey, Marika Holland, Nicole Lovenduski, Warren G. Strand, and Teagan King
Geosci. Model Dev., 15, 6451–6493, https://doi.org/10.5194/gmd-15-6451-2022, https://doi.org/10.5194/gmd-15-6451-2022, 2022
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The Earth system changes over a range of time and space scales, and some of these changes are predictable in advance. Short-term weather forecasts are most familiar, but recent work has shown that it is possible to generate useful predictions several seasons or even a decade in advance. This study focuses on predictions over intermediate timescales (up to 24 months in advance) and shows that there is promising potential to forecast a variety of changes in the natural environment.
Mari R. Tye, Katherine Dagon, Maria J. Molina, Jadwiga H. Richter, Daniele Visioni, Ben Kravitz, and Simone Tilmes
Earth Syst. Dynam., 13, 1233–1257, https://doi.org/10.5194/esd-13-1233-2022, https://doi.org/10.5194/esd-13-1233-2022, 2022
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We examined the potential effect of stratospheric aerosol injection (SAI) on extreme temperature and precipitation. SAI may cause daytime temperatures to cool but nighttime to warm. Daytime cooling may occur in all seasons across the globe, with the largest decreases in summer. In contrast, nighttime warming may be greatest at high latitudes in winter. SAI may reduce the frequency and intensity of extreme rainfall. The combined changes may exacerbate drying over parts of the global south.
Ewa M. Bednarz, Ryan Hossaini, Martyn P. Chipperfield, N. Luke Abraham, and Peter Braesicke
Atmos. Chem. Phys., 22, 10657–10676, https://doi.org/10.5194/acp-22-10657-2022, https://doi.org/10.5194/acp-22-10657-2022, 2022
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Atmospheric impacts of chlorinated very short-lived substances (Cl-VSLS) over the first two decades of the 21st century are assessed using the UM-UKCA chemistry–climate model. Stratospheric input of Cl from Cl-VSLS is estimated at ~130 ppt in 2019. The use of model set-up with constrained meteorology significantly increases the abundance of Cl-VSLS in the lower stratosphere relative to the free-running set-up. The growth in Cl-VSLS emissions significantly impacted recent HCl and COCl2 trends.
Zachary D. Lawrence, Marta Abalos, Blanca Ayarzagüena, David Barriopedro, Amy H. Butler, Natalia Calvo, Alvaro de la Cámara, Andrew Charlton-Perez, Daniela I. V. Domeisen, Etienne Dunn-Sigouin, Javier García-Serrano, Chaim I. Garfinkel, Neil P. Hindley, Liwei Jia, Martin Jucker, Alexey Y. Karpechko, Hera Kim, Andrea L. Lang, Simon H. Lee, Pu Lin, Marisol Osman, Froila M. Palmeiro, Judith Perlwitz, Inna Polichtchouk, Jadwiga H. Richter, Chen Schwartz, Seok-Woo Son, Irene Erner, Masakazu Taguchi, Nicholas L. Tyrrell, Corwin J. Wright, and Rachel W.-Y. Wu
Weather Clim. Dynam., 3, 977–1001, https://doi.org/10.5194/wcd-3-977-2022, https://doi.org/10.5194/wcd-3-977-2022, 2022
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Forecast models that are used to predict weather often struggle to represent the Earth’s stratosphere. This may impact their ability to predict surface weather weeks in advance, on subseasonal-to-seasonal (S2S) timescales. We use data from many S2S forecast systems to characterize and compare the stratospheric biases present in such forecast models. These models have many similar stratospheric biases, but they tend to be worse in systems with low model tops located within the stratosphere.
Peter Hitchcock, Amy Butler, Andrew Charlton-Perez, Chaim I. Garfinkel, Tim Stockdale, James Anstey, Dann Mitchell, Daniela I. V. Domeisen, Tongwen Wu, Yixiong Lu, Daniele Mastrangelo, Piero Malguzzi, Hai Lin, Ryan Muncaster, Bill Merryfield, Michael Sigmond, Baoqiang Xiang, Liwei Jia, Yu-Kyung Hyun, Jiyoung Oh, Damien Specq, Isla R. Simpson, Jadwiga H. Richter, Cory Barton, Jeff Knight, Eun-Pa Lim, and Harry Hendon
Geosci. Model Dev., 15, 5073–5092, https://doi.org/10.5194/gmd-15-5073-2022, https://doi.org/10.5194/gmd-15-5073-2022, 2022
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This paper describes an experimental protocol focused on sudden stratospheric warmings to be carried out by subseasonal forecast modeling centers. These will allow for inter-model comparisons of these major disruptions to the stratospheric polar vortex and their impacts on the near-surface flow. The protocol will lead to new insights into the contribution of the stratosphere to subseasonal forecast skill and new approaches to the dynamical attribution of extreme events.
Jim M. Haywood, Andy Jones, Ben T. Johnson, and William McFarlane Smith
Atmos. Chem. Phys., 22, 6135–6150, https://doi.org/10.5194/acp-22-6135-2022, https://doi.org/10.5194/acp-22-6135-2022, 2022
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Simulations are presented investigating the influence of moderately absorbing aerosol in the stratosphere to combat the impacts of climate change. A number of detrimental impacts are noted compared to sulfate aerosol, including (i) reduced cooling efficiency, (ii) increased deficits in global precipitation, (iii) delays in the recovery of the stratospheric ozone hole, and (iv) disruption of the stratospheric circulation and the wintertime storm tracks that impact European precipitation.
Ilaria Quaglia, Daniele Visioni, Giovanni Pitari, and Ben Kravitz
Atmos. Chem. Phys., 22, 5757–5773, https://doi.org/10.5194/acp-22-5757-2022, https://doi.org/10.5194/acp-22-5757-2022, 2022
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Carbonyl sulfide is a gas that mixes very well in the atmosphere and can reach the stratosphere, where it reacts with sunlight and produces aerosol. Here we propose that, by increasing surface fluxes by an order of magnitude, the number of stratospheric aerosols produced may be enough to partially offset the warming produced by greenhouse gases. We explore what effect this would have on the atmospheric composition.
Simone Tilmes, Daniele Visioni, Andy Jones, James Haywood, Roland Séférian, Pierre Nabat, Olivier Boucher, Ewa Monica Bednarz, and Ulrike Niemeier
Atmos. Chem. Phys., 22, 4557–4579, https://doi.org/10.5194/acp-22-4557-2022, https://doi.org/10.5194/acp-22-4557-2022, 2022
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This study assesses the impacts of climate interventions, using stratospheric sulfate aerosol and solar dimming on stratospheric ozone, based on three Earth system models with interactive stratospheric chemistry. The climate interventions have been applied to a high emission (baseline) scenario in order to reach global surface temperatures of a medium emission scenario. We find significant increases and decreases in total column ozone, depending on regions and seasons.
Huiying Ren, Erol Cromwell, Ben Kravitz, and Xingyuan Chen
Hydrol. Earth Syst. Sci., 26, 1727–1743, https://doi.org/10.5194/hess-26-1727-2022, https://doi.org/10.5194/hess-26-1727-2022, 2022
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We used a deep learning method called long short-term memory (LSTM) to fill gaps in data collected by hydrologic monitoring networks. LSTM accounted for correlations in space and time and nonlinear trends in data. Compared to a traditional regression-based time-series method, LSTM performed comparably when filling gaps in data with smooth patterns, while it better captured highly dynamic patterns in data. Capturing such dynamics is critical for understanding dynamic complex system behaviors.
Andy Jones, Jim M. Haywood, Adam A. Scaife, Olivier Boucher, Matthew Henry, Ben Kravitz, Thibaut Lurton, Pierre Nabat, Ulrike Niemeier, Roland Séférian, Simone Tilmes, and Daniele Visioni
Atmos. Chem. Phys., 22, 2999–3016, https://doi.org/10.5194/acp-22-2999-2022, https://doi.org/10.5194/acp-22-2999-2022, 2022
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Simulations by six Earth-system models of geoengineering by introducing sulfuric acid aerosols into the tropical stratosphere are compared. A robust impact on the northern wintertime North Atlantic Oscillation is found, exacerbating precipitation reduction over parts of southern Europe. In contrast, the models show no consistency with regard to impacts on the Quasi-Biennial Oscillation, although results do indicate a risk that the oscillation could become locked into a permanent westerly phase.
Debra K. Weisenstein, Daniele Visioni, Henning Franke, Ulrike Niemeier, Sandro Vattioni, Gabriel Chiodo, Thomas Peter, and David W. Keith
Atmos. Chem. Phys., 22, 2955–2973, https://doi.org/10.5194/acp-22-2955-2022, https://doi.org/10.5194/acp-22-2955-2022, 2022
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This paper explores a potential method of geoengineering that could be used to slow the rate of change of climate over decadal scales. We use three climate models to explore how injections of accumulation-mode sulfuric acid aerosol change the large-scale stratospheric particle size distribution and radiative forcing response for the chosen scenarios. Radiative forcing per unit sulfur injected and relative to the change in aerosol burden is larger with particulate than with SO2 injections.
Florian Haenel, Wolfgang Woiwode, Jennifer Buchmüller, Felix Friedl-Vallon, Michael Höpfner, Sören Johansson, Farahnaz Khosrawi, Oliver Kirner, Anne Kleinert, Hermann Oelhaf, Johannes Orphal, Roland Ruhnke, Björn-Martin Sinnhuber, Jörn Ungermann, Michael Weimer, and Peter Braesicke
Atmos. Chem. Phys., 22, 2843–2870, https://doi.org/10.5194/acp-22-2843-2022, https://doi.org/10.5194/acp-22-2843-2022, 2022
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We compare remote sensing observations of H2O, O3, HNO3 and clouds in the upper troposphere–lowermost stratosphere during an Arctic winter long-range research flight with simulations by two different state-of-the-art model systems. We find good agreement for dynamical structures, trace gas distributions and clouds. We investigate model biases and sensitivities, with the goal of aiding model development and improving our understanding of processes in the upper troposphere–lowermost stratosphere.
Adam A. Scaife, Mark P. Baldwin, Amy H. Butler, Andrew J. Charlton-Perez, Daniela I. V. Domeisen, Chaim I. Garfinkel, Steven C. Hardiman, Peter Haynes, Alexey Yu Karpechko, Eun-Pa Lim, Shunsuke Noguchi, Judith Perlwitz, Lorenzo Polvani, Jadwiga H. Richter, John Scinocca, Michael Sigmond, Theodore G. Shepherd, Seok-Woo Son, and David W. J. Thompson
Atmos. Chem. Phys., 22, 2601–2623, https://doi.org/10.5194/acp-22-2601-2022, https://doi.org/10.5194/acp-22-2601-2022, 2022
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Great progress has been made in computer modelling and simulation of the whole climate system, including the stratosphere. Since the late 20th century we also gained a much clearer understanding of how the stratosphere interacts with the lower atmosphere. The latest generation of numerical prediction systems now explicitly represents the stratosphere and its interaction with surface climate, and here we review its role in long-range predictions and projections from weeks to decades ahead.
Daniele Visioni, Simone Tilmes, Charles Bardeen, Michael Mills, Douglas G. MacMartin, Ben Kravitz, and Jadwiga H. Richter
Atmos. Chem. Phys., 22, 1739–1756, https://doi.org/10.5194/acp-22-1739-2022, https://doi.org/10.5194/acp-22-1739-2022, 2022
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Aerosols are simulated in a simplified way in climate models: in the model analyzed here, they are represented in every grid as described by three simple logarithmic distributions, mixing all different species together. The size can evolve when new particles are formed, particles merge together to create a larger one or particles are deposited to the surface. This approximation normally works fairly well. Here we show however that when large amounts of sulfate are simulated, there are problems.
Yan Zhang, Douglas G. MacMartin, Daniele Visioni, and Ben Kravitz
Earth Syst. Dynam., 13, 201–217, https://doi.org/10.5194/esd-13-201-2022, https://doi.org/10.5194/esd-13-201-2022, 2022
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Adding SO2 to the stratosphere could temporarily cool the planet by reflecting more sunlight back to space. However, adding SO2 at different latitude(s) and season(s) leads to significant differences in regional surface climate. This study shows that, to cool the planet by 1–1.5 °C, there are likely six to eight choices of injection latitude(s) and season(s) that lead to meaningfully different distributions of climate impacts.
Anton Laakso, Ulrike Niemeier, Daniele Visioni, Simone Tilmes, and Harri Kokkola
Atmos. Chem. Phys., 22, 93–118, https://doi.org/10.5194/acp-22-93-2022, https://doi.org/10.5194/acp-22-93-2022, 2022
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The use of different spatio-temporal sulfur injection strategies with different magnitudes to create an artificial reflective aerosol layer to cool the climate is studied using sectional and modal aerosol schemes in a climate model. There are significant differences in the results depending on the aerosol microphysical module used. Different spatio-temporal injection strategies have a significant impact on the magnitude and zonal distribution of radiative forcing and atmospheric dynamics.
Christopher J. Diekmann, Matthias Schneider, Benjamin Ertl, Frank Hase, Omaira García, Farahnaz Khosrawi, Eliezer Sepúlveda, Peter Knippertz, and Peter Braesicke
Earth Syst. Sci. Data, 13, 5273–5292, https://doi.org/10.5194/essd-13-5273-2021, https://doi.org/10.5194/essd-13-5273-2021, 2021
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The joint analysis of different stable water isotopes in water vapour is a powerful tool for investigating atmospheric moisture pathways. This paper presents a novel global and multi-annual dataset of H2O and HDO in mid-tropospheric water vapour by using data from the satellite sensor Metop/IASI. Due to its unique combination of coverage and resolution in space and time, this dataset is highly promising for studying the hydrological cycle and its representation in weather and climate models.
Zixia Liu, Martin Osborne, Karen Anderson, Jamie D. Shutler, Andy Wilson, Justin Langridge, Steve H. L. Yim, Hugh Coe, Suresh Babu, Sreedharan K. Satheesh, Paquita Zuidema, Tao Huang, Jack C. H. Cheng, and James Haywood
Atmos. Meas. Tech., 14, 6101–6118, https://doi.org/10.5194/amt-14-6101-2021, https://doi.org/10.5194/amt-14-6101-2021, 2021
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This paper first validates the performance of an advanced aerosol observation instrument POPS against a reference instrument and examines any biases introduced by operating it on a quadcopter drone. The results show the POPS performs relatively well on the ground. The impact of the UAV rotors on the POPS is small at low wind speeds, but when operating under higher wind speeds, larger discrepancies occur. It appears that the POPS measures sub-micron aerosol particles more accurately on the UAV.
Dawn L. Woodard, Alexey N. Shiklomanov, Ben Kravitz, Corinne Hartin, and Ben Bond-Lamberty
Geosci. Model Dev., 14, 4751–4767, https://doi.org/10.5194/gmd-14-4751-2021, https://doi.org/10.5194/gmd-14-4751-2021, 2021
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We have added a representation of the permafrost carbon feedback to the simple, open-source global carbon–climate model Hector and calibrated the results to be consistent with historical data and Earth system model projections. Our results closely match previous work, estimating around 0.2 °C of warming from permafrost this century. This capability will be useful to explore uncertainties in this feedback and for coupling with integrated assessment models for policy and economic analysis.
Daniele Visioni, Douglas G. MacMartin, Ben Kravitz, Olivier Boucher, Andy Jones, Thibaut Lurton, Michou Martine, Michael J. Mills, Pierre Nabat, Ulrike Niemeier, Roland Séférian, and Simone Tilmes
Atmos. Chem. Phys., 21, 10039–10063, https://doi.org/10.5194/acp-21-10039-2021, https://doi.org/10.5194/acp-21-10039-2021, 2021
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A new set of simulations is used to investigate commonalities, differences and sources of uncertainty when simulating the injection of SO2 in the stratosphere in order to mitigate the effects of climate change (solar geoengineering). The models differ in how they simulate the aerosols and how they spread around the stratosphere, resulting in differences in projected regional impacts. Overall, however, the models agree that aerosols have the potential to mitigate the warming produced by GHGs.
Michael Weimer, Jennifer Buchmüller, Lars Hoffmann, Ole Kirner, Beiping Luo, Roland Ruhnke, Michael Steiner, Ines Tritscher, and Peter Braesicke
Atmos. Chem. Phys., 21, 9515–9543, https://doi.org/10.5194/acp-21-9515-2021, https://doi.org/10.5194/acp-21-9515-2021, 2021
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We show that we are able to directly simulate polar stratospheric clouds formed locally in a mountain wave and represent their effect on the ozone chemistry with the global atmospheric chemistry model ICON-ART. Thus, we show the first simulations that close the gap between directly resolved mountain-wave-induced polar stratospheric clouds and their representation at coarse global resolutions.
Nikolas O. Aksamit, Ben Kravitz, Douglas G. MacMartin, and George Haller
Atmos. Chem. Phys., 21, 8845–8861, https://doi.org/10.5194/acp-21-8845-2021, https://doi.org/10.5194/acp-21-8845-2021, 2021
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There exist robust and influential material features evolving within turbulent fluids that behave as the skeleton for fluid transport pathways. Recent developments in applied mathematics have made the identification of these time-varying structures more rigorous and insightful than ever. Using short-range wind forecasts, we detail how and why these material features can be exploited in an effort to optimize the spread of aerosols in the stratosphere for climate geoengineering.
Henning Franke, Ulrike Niemeier, and Daniele Visioni
Atmos. Chem. Phys., 21, 8615–8635, https://doi.org/10.5194/acp-21-8615-2021, https://doi.org/10.5194/acp-21-8615-2021, 2021
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Stratospheric aerosol modification (SAM) can alter the quasi-biennial oscillation (QBO). Our simulations with two different models show that the characteristics of the QBO response are primarily determined by the meridional structure of the aerosol-induced heating. Therefore, the QBO response to SAM depends primarily on the location of injection, while injection type and rate act to scale the specific response. Our results have important implications for evaluating adverse side effects of SAM.
Ben Kravitz, Douglas G. MacMartin, Daniele Visioni, Olivier Boucher, Jason N. S. Cole, Jim Haywood, Andy Jones, Thibaut Lurton, Pierre Nabat, Ulrike Niemeier, Alan Robock, Roland Séférian, and Simone Tilmes
Atmos. Chem. Phys., 21, 4231–4247, https://doi.org/10.5194/acp-21-4231-2021, https://doi.org/10.5194/acp-21-4231-2021, 2021
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This study investigates multi-model response to idealized geoengineering (high CO2 with solar reduction) across two different generations of climate models. We find that, with the exception of a few cases, the results are unchanged between the different generations. This gives us confidence that broad conclusions about the response to idealized geoengineering are robust.
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Short summary
Building on Part 1 of this two-part study, we demonstrate the role of biases in climatological circulation and specific aspects of model microphysics in driving the differences in simulated sulfate distributions amongst three Earth system models. We then characterize the simulated changes in stratospheric and free-tropospheric temperatures, ozone, water vapor, and large-scale circulation, elucidating the role of the above aspects in the surface responses discussed in Part 1.
Building on Part 1 of this two-part study, we demonstrate the role of biases in climatological...
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