Articles | Volume 23, issue 14
https://doi.org/10.5194/acp-23-8259-2023
© 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-23-8259-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
ACP Letters
| Highlight paper
| 
25 Jul 2023
ACP Letters | Highlight paper |
| 25 Jul 2023
| 25 Jul 2023
Detection of large-scale cloud microphysical changes within a major shipping corridor after implementation of the International Maritime Organization 2020 fuel sulfur regulations
Department of Earth, Ocean and Atmospheric Science, Florida State
University, Tallahassee, FL 32306, USA
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Cited
52 citations as recorded by crossref.
- Key Gaps in Models' Physical Representation of Climate Intervention and Its Impacts S. Eastham et al. https://doi.org/10.1029/2024MS004872
- Detection of large-scale cloud microphysical changes within a major shipping corridor after implementation of the International Maritime Organization 2020 fuel sulfur regulations M. Diamond https://doi.org/10.5194/acp-23-8259-2023
- Planetary albedo and reflected shortwave flux: Basic characteristics, mechanisms of change and future projections R. Li et al. https://doi.org/10.1016/j.earscirev.2025.105274
- Physical science research needed to evaluate the viability and risks of marine cloud brightening G. Feingold et al. https://doi.org/10.1126/sciadv.adi8594
- Atmospheric patterns drive marine heatwaves in the North Atlantic and Mediterranean Sea during summer 2023 L. Behr et al. https://doi.org/10.1088/1748-9326/ae0055
- Quantification of the influence of anthropogenic and natural factors on the record-high temperatures in 2023 and 2024 E. Farago et al. https://doi.org/10.5194/esd-17-451-2026
- Drivers of the extreme North Atlantic marine heatwave during 2023 M. England et al. https://doi.org/10.1038/s41586-025-08903-5
- Analysis of ship emission effects on clouds over the southeastern Atlantic using geostationary satellite observations N. Benas et al. https://doi.org/10.5194/acp-25-6957-2025
- Recent global temperature surge intensified by record-low planetary albedo H. Goessling et al. https://doi.org/10.1126/science.adq7280
- Conflict-induced ship traffic disruptions constrain cloud sensitivity to stricter marine pollution regulations M. Diamond & L. Boss https://doi.org/10.5194/acp-25-16401-2025
- The high-resolution global shipping emission inventory by the Shipping Emission Inventory Model (SEIM) W. Yi et al. https://doi.org/10.5194/essd-17-277-2025
- World Climate Research Programme lighthouse activity: an assessment of major research gaps in solar radiation modification research J. Haywood et al. https://doi.org/10.3389/fclim.2025.1507479
- Mixing State, Morphology, and Chemical Composition of Ship-Emitted Soot Revealed by UAV-Based Plume Observations S. Bie et al. https://doi.org/10.1021/acs.est.6c00632
- Cutting ships’ pollution has climate downside https://doi.org/10.1038/d41586-023-02430-x
- Decomposing the global and regional aerosol effective radiative forcing associated with strong versus weak air quality policies by Mid-21st century R. Allen et al. https://doi.org/10.1088/2752-5295/ae5418
- Lightning declines over shipping lanes following regulation of fuel sulfur emissions C. Wright et al. https://doi.org/10.5194/acp-25-2937-2025
- Global and regional drivers for exceptional climate extremes in 2023-2024: beyond the new normal S. Minobe et al. https://doi.org/10.1038/s41612-025-00996-z
- Radiative forcing from the 2020 shipping fuel regulation is large but hard to detect J. Zhang et al. https://doi.org/10.1038/s43247-024-01911-9
- Observational evidence of reduced Bay of Bengal lightning since 2020 linked to cloud responses to shipping emission regulations Q. Jin et al. https://doi.org/10.1038/s41612-025-01256-w
- Rent-seeking behavior of ship sulfur emission detection based on evolutionary game theory J. Liang et al. https://doi.org/10.1016/j.rsma.2025.104060
- Multi-model effective radiative forcing of the 2020 sulfur cap for shipping R. Skeie et al. https://doi.org/10.5194/acp-24-13361-2024
- G6-1.5K-MCB: Marine Cloud Brightening scenario design for the Geoengineering Model Intercomparison Project (GeoMIP) in CESM2.1, E3SMv2.0, and UKESM1.1 H. Hirasawa et al. https://doi.org/10.5194/gmd-19-3257-2026
- Identifying when thresholds from the Paris Agreement are breached: the minmax average, a novel smoothing approach M. Van Vyve https://doi.org/10.1093/oxfclm/kgae009
- Impact of Ship Emission Control Area Policies on Port Air Quality—A Case Study of Ningbo Port, China S. Lu & F. Zhou https://doi.org/10.3390/su16093659
- Detectable ship tracks account for just 5% of aerosol indirect forcing from ship emissions T. Yuan et al. https://doi.org/10.1038/s43247-025-02825-w
- Modifications on the coastal atmospheric sulfur and cloud condensation nuclei along the Eastern China seas by shipping fuel transition J. Mao et al. https://doi.org/10.1016/j.scitotenv.2024.173142
- Jump in Tropospheric Methane Concentrations in 2020–2021 and Slowdown in 2022–2024: New Hypotheses on Causation T. Ming et al. https://doi.org/10.3390/atmos16040406
- Abrupt reduction in shipping emission as an inadvertent geoengineering termination shock produces substantial radiative warming T. Yuan et al. https://doi.org/10.1038/s43247-024-01442-3
- Addressing the urgent need for direct climate cooling: Rationale and options R. Baiman et al. https://doi.org/10.1093/oxfclm/kgae014
- Highly light-absorbing particle emissions from low-sulfur marine fuels T. Kokkola et al. https://doi.org/10.1038/s41612-026-01369-w
- Observational Assessment of Changes in Earth’s Energy Imbalance Since 2000 N. Loeb et al. https://doi.org/10.1007/s10712-024-09838-8
- Lightning response to temperature and aerosols X. Qie et al. https://doi.org/10.1088/1748-9326/ad63bf
- A global overview of marine heatwaves in a changing climate A. Capotondi et al. https://doi.org/10.1038/s43247-024-01806-9
- Global Black Carbon Aerosol: Spatiotemporal Distributions, Drivers, and Health Impacts H. Yu et al. https://doi.org/10.1016/j.jhazmat.2026.142933
- Spatiotemporal and sectoral dynamics of air pollutants and greenhouse gas emissions in Nigeria (1970–2023) D. Omokpariola https://doi.org/10.1007/s44274-026-00821-1
- Recent Advances in the Observation and Modeling of Aerosol-Cloud Interactions, Cloud Feedbacks, and Earth’s Energy Imbalance: A Review T. Michibata et al. https://doi.org/10.1007/s40726-025-00382-6
- The HTAP_v3.2 emission mosaic: merging regional and global monthly emissions (2000–2020) to support air quality modelling and policies D. Guizzardi et al. https://doi.org/10.5194/essd-17-5915-2025
- An Entropy Generation Rate Model for Tropospheric Behavior That Includes Cloud Evolution J. Sekhar https://doi.org/10.3390/e25121625
- Ship emission variations during the COVID-19 from global and continental perspectives W. Yi et al. https://doi.org/10.1016/j.scitotenv.2024.176633
- Impact on cloud properties of reduced-sulphur shipping fuel in the Eastern North Atlantic G. Mace et al. https://doi.org/10.5194/acp-26-1041-2026
- Global warming in the pipeline J. Hansen et al. https://doi.org/10.1093/oxfclm/kgad008
- Scenario aware multi pollutant emissions forecasting for India using hybrid ridge-VARX and gradient boosting with inequality aware reconciliation G. Kannaiyan et al. https://doi.org/10.1088/2515-7620/ae44ea
- Darkening clouds after restrictions in maritime sulfur emissions E. Scott https://doi.org/10.1038/s43017-023-00490-1
- An intercomparison of aircraft sulfur dioxide measurements in clean and polluted marine environments L. Temple et al. https://doi.org/10.5194/amt-19-1165-2026
- Impact of fuel sulfur regulations on carbonaceous particle emission from a marine engine M. Bauer et al. https://doi.org/10.1038/s41612-024-00838-4
- Climate warming could weaken aerosol-cloud interactions in subtropical marine stratocumulus H. Sun et al. https://doi.org/10.1038/s41612-026-01357-0
- Surface temperature effects of recent reductions in shipping SO2 emissions are within internal variability D. Watson-Parris et al. https://doi.org/10.5194/acp-25-4443-2025
- Effects of intermittent aerosol forcing on the stratocumulus-to-cumulus transition P. Prabhakaran et al. https://doi.org/10.5194/acp-24-1919-2024
- Reconciling Earth’s growing energy imbalance with ocean warming R. Allan & C. Merchant https://doi.org/10.1088/1748-9326/adb448
- Evaluating simulations of ship tracks in a km-scale model A. Tippett et al. https://doi.org/10.5194/acp-26-4251-2026
- Rapid saturation of cloud water adjustments to shipping emissions P. Manshausen et al. https://doi.org/10.5194/acp-23-12545-2023
- An open letter to the IMO supporting maritime transport that cools the atmosphere while preserving air quality benefits R. Baiman et al. https://doi.org/10.1093/oxfclm/kgae008
52 citations as recorded by crossref.
- Key Gaps in Models' Physical Representation of Climate Intervention and Its Impacts S. Eastham et al. https://doi.org/10.1029/2024MS004872
- Detection of large-scale cloud microphysical changes within a major shipping corridor after implementation of the International Maritime Organization 2020 fuel sulfur regulations M. Diamond https://doi.org/10.5194/acp-23-8259-2023
- Planetary albedo and reflected shortwave flux: Basic characteristics, mechanisms of change and future projections R. Li et al. https://doi.org/10.1016/j.earscirev.2025.105274
- Physical science research needed to evaluate the viability and risks of marine cloud brightening G. Feingold et al. https://doi.org/10.1126/sciadv.adi8594
- Atmospheric patterns drive marine heatwaves in the North Atlantic and Mediterranean Sea during summer 2023 L. Behr et al. https://doi.org/10.1088/1748-9326/ae0055
- Quantification of the influence of anthropogenic and natural factors on the record-high temperatures in 2023 and 2024 E. Farago et al. https://doi.org/10.5194/esd-17-451-2026
- Drivers of the extreme North Atlantic marine heatwave during 2023 M. England et al. https://doi.org/10.1038/s41586-025-08903-5
- Analysis of ship emission effects on clouds over the southeastern Atlantic using geostationary satellite observations N. Benas et al. https://doi.org/10.5194/acp-25-6957-2025
- Recent global temperature surge intensified by record-low planetary albedo H. Goessling et al. https://doi.org/10.1126/science.adq7280
- Conflict-induced ship traffic disruptions constrain cloud sensitivity to stricter marine pollution regulations M. Diamond & L. Boss https://doi.org/10.5194/acp-25-16401-2025
- The high-resolution global shipping emission inventory by the Shipping Emission Inventory Model (SEIM) W. Yi et al. https://doi.org/10.5194/essd-17-277-2025
- World Climate Research Programme lighthouse activity: an assessment of major research gaps in solar radiation modification research J. Haywood et al. https://doi.org/10.3389/fclim.2025.1507479
- Mixing State, Morphology, and Chemical Composition of Ship-Emitted Soot Revealed by UAV-Based Plume Observations S. Bie et al. https://doi.org/10.1021/acs.est.6c00632
- Cutting ships’ pollution has climate downside https://doi.org/10.1038/d41586-023-02430-x
- Decomposing the global and regional aerosol effective radiative forcing associated with strong versus weak air quality policies by Mid-21st century R. Allen et al. https://doi.org/10.1088/2752-5295/ae5418
- Lightning declines over shipping lanes following regulation of fuel sulfur emissions C. Wright et al. https://doi.org/10.5194/acp-25-2937-2025
- Global and regional drivers for exceptional climate extremes in 2023-2024: beyond the new normal S. Minobe et al. https://doi.org/10.1038/s41612-025-00996-z
- Radiative forcing from the 2020 shipping fuel regulation is large but hard to detect J. Zhang et al. https://doi.org/10.1038/s43247-024-01911-9
- Observational evidence of reduced Bay of Bengal lightning since 2020 linked to cloud responses to shipping emission regulations Q. Jin et al. https://doi.org/10.1038/s41612-025-01256-w
- Rent-seeking behavior of ship sulfur emission detection based on evolutionary game theory J. Liang et al. https://doi.org/10.1016/j.rsma.2025.104060
- Multi-model effective radiative forcing of the 2020 sulfur cap for shipping R. Skeie et al. https://doi.org/10.5194/acp-24-13361-2024
- G6-1.5K-MCB: Marine Cloud Brightening scenario design for the Geoengineering Model Intercomparison Project (GeoMIP) in CESM2.1, E3SMv2.0, and UKESM1.1 H. Hirasawa et al. https://doi.org/10.5194/gmd-19-3257-2026
- Identifying when thresholds from the Paris Agreement are breached: the minmax average, a novel smoothing approach M. Van Vyve https://doi.org/10.1093/oxfclm/kgae009
- Impact of Ship Emission Control Area Policies on Port Air Quality—A Case Study of Ningbo Port, China S. Lu & F. Zhou https://doi.org/10.3390/su16093659
- Detectable ship tracks account for just 5% of aerosol indirect forcing from ship emissions T. Yuan et al. https://doi.org/10.1038/s43247-025-02825-w
- Modifications on the coastal atmospheric sulfur and cloud condensation nuclei along the Eastern China seas by shipping fuel transition J. Mao et al. https://doi.org/10.1016/j.scitotenv.2024.173142
- Jump in Tropospheric Methane Concentrations in 2020–2021 and Slowdown in 2022–2024: New Hypotheses on Causation T. Ming et al. https://doi.org/10.3390/atmos16040406
- Abrupt reduction in shipping emission as an inadvertent geoengineering termination shock produces substantial radiative warming T. Yuan et al. https://doi.org/10.1038/s43247-024-01442-3
- Addressing the urgent need for direct climate cooling: Rationale and options R. Baiman et al. https://doi.org/10.1093/oxfclm/kgae014
- Highly light-absorbing particle emissions from low-sulfur marine fuels T. Kokkola et al. https://doi.org/10.1038/s41612-026-01369-w
- Observational Assessment of Changes in Earth’s Energy Imbalance Since 2000 N. Loeb et al. https://doi.org/10.1007/s10712-024-09838-8
- Lightning response to temperature and aerosols X. Qie et al. https://doi.org/10.1088/1748-9326/ad63bf
- A global overview of marine heatwaves in a changing climate A. Capotondi et al. https://doi.org/10.1038/s43247-024-01806-9
- Global Black Carbon Aerosol: Spatiotemporal Distributions, Drivers, and Health Impacts H. Yu et al. https://doi.org/10.1016/j.jhazmat.2026.142933
- Spatiotemporal and sectoral dynamics of air pollutants and greenhouse gas emissions in Nigeria (1970–2023) D. Omokpariola https://doi.org/10.1007/s44274-026-00821-1
- Recent Advances in the Observation and Modeling of Aerosol-Cloud Interactions, Cloud Feedbacks, and Earth’s Energy Imbalance: A Review T. Michibata et al. https://doi.org/10.1007/s40726-025-00382-6
- The HTAP_v3.2 emission mosaic: merging regional and global monthly emissions (2000–2020) to support air quality modelling and policies D. Guizzardi et al. https://doi.org/10.5194/essd-17-5915-2025
- An Entropy Generation Rate Model for Tropospheric Behavior That Includes Cloud Evolution J. Sekhar https://doi.org/10.3390/e25121625
- Ship emission variations during the COVID-19 from global and continental perspectives W. Yi et al. https://doi.org/10.1016/j.scitotenv.2024.176633
- Impact on cloud properties of reduced-sulphur shipping fuel in the Eastern North Atlantic G. Mace et al. https://doi.org/10.5194/acp-26-1041-2026
- Global warming in the pipeline J. Hansen et al. https://doi.org/10.1093/oxfclm/kgad008
- Scenario aware multi pollutant emissions forecasting for India using hybrid ridge-VARX and gradient boosting with inequality aware reconciliation G. Kannaiyan et al. https://doi.org/10.1088/2515-7620/ae44ea
- Darkening clouds after restrictions in maritime sulfur emissions E. Scott https://doi.org/10.1038/s43017-023-00490-1
- An intercomparison of aircraft sulfur dioxide measurements in clean and polluted marine environments L. Temple et al. https://doi.org/10.5194/amt-19-1165-2026
- Impact of fuel sulfur regulations on carbonaceous particle emission from a marine engine M. Bauer et al. https://doi.org/10.1038/s41612-024-00838-4
- Climate warming could weaken aerosol-cloud interactions in subtropical marine stratocumulus H. Sun et al. https://doi.org/10.1038/s41612-026-01357-0
- Surface temperature effects of recent reductions in shipping SO2 emissions are within internal variability D. Watson-Parris et al. https://doi.org/10.5194/acp-25-4443-2025
- Effects of intermittent aerosol forcing on the stratocumulus-to-cumulus transition P. Prabhakaran et al. https://doi.org/10.5194/acp-24-1919-2024
- Reconciling Earth’s growing energy imbalance with ocean warming R. Allan & C. Merchant https://doi.org/10.1088/1748-9326/adb448
- Evaluating simulations of ship tracks in a km-scale model A. Tippett et al. https://doi.org/10.5194/acp-26-4251-2026
- Rapid saturation of cloud water adjustments to shipping emissions P. Manshausen et al. https://doi.org/10.5194/acp-23-12545-2023
- An open letter to the IMO supporting maritime transport that cools the atmosphere while preserving air quality benefits R. Baiman et al. https://doi.org/10.1093/oxfclm/kgae008
Saved (final revised paper)
Latest update: 19 Jul 2026
Editorial statement
In 2020, a new international law was imposed that placed strong restrictions on sulfur emissions from the international shipping industry. In addition to reducing air pollution, an anticipated side effect was reduction of the climate cooling effect that is often associated with "ship-tracks". Aerosol pollutant emissions from ships, when they rise into overlying clouds, lead to higher cloud droplet number concentrations, smaller cloud droplet sizes, and clouds that are more reflective to incoming sunlight, easily seen in satellite imagery as long bright lines downwind of ships. Past studies into whether the new law has led to darker clouds have been equivocal. For this study, the authors used sophisticated statistical techniques to compare cloud droplet size and reflectivity before and after the law was implemented focusing on a shipping corridor in the southeast Atlantic. They found strong evidence that droplet sizes have indeed increased, and that clouds have darkened with a significant local climate warming. Globally, the impact is much smaller, but may still represent an important consideration for assessments of the total summed effect of aerosols on climate.
In 2020, a new international law was imposed that placed strong restrictions on sulfur emissions...
Short summary
Fuel sulfur regulations were implemented for ships in 2020 to improve air quality but may also accelerate global warming. We use spatial statistics and satellite retrievals to detect changes in the size of cloud droplets and find evidence for a resulting decrease in cloud brightness within a major shipping corridor after the sulfur limits went into effect. Our results confirm both that the regulations are being followed and that they are having a warming influence via their effect on clouds.
Fuel sulfur regulations were implemented for ships in 2020 to improve air quality but may also...
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