1
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Yuan T, Song H, Oreopoulos L, Wood R, Bian H, Breen K, Chin M, Yu H, Barahona D, Meyer K, Platnick S. Abrupt reduction in shipping emission as an inadvertent geoengineering termination shock produces substantial radiative warming. COMMUNICATIONS EARTH & ENVIRONMENT 2024; 5:281. [PMID: 38826490 PMCID: PMC11139642 DOI: 10.1038/s43247-024-01442-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 05/08/2024] [Indexed: 06/04/2024]
Abstract
Human activities affect the Earth's climate through modifying the composition of the atmosphere, which then creates radiative forcing that drives climate change. The warming effect of anthropogenic greenhouse gases has been partially balanced by the cooling effect of anthropogenic aerosols. In 2020, fuel regulations abruptly reduced the emission of sulfur dioxide from international shipping by about 80% and created an inadvertent geoengineering termination shock with global impact. Here we estimate the regulation leads to a radiative forcing of + 0.2 ± 0.11 Wm-2 averaged over the global ocean. The amount of radiative forcing could lead to a doubling (or more) of the warming rate in the 2020 s compared with the rate since 1980 with strong spatiotemporal heterogeneity. The warming effect is consistent with the recent observed strong warming in 2023 and expected to make the 2020 s anomalously warm. The forcing is equivalent in magnitude to 80% of the measured increase in planetary heat uptake since 2020. The radiative forcing also has strong hemispheric contrast, which has important implications for precipitation pattern changes. Our result suggests marine cloud brightening may be a viable geoengineering method in temporarily cooling the climate that has its unique challenges due to inherent spatiotemporal heterogeneity.
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Affiliation(s)
- Tianle Yuan
- GESTAR-II, University of Maryland, Baltimore County, MD USA
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
| | - Hua Song
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
- SSAI, Inc., Lanham, MD USA
| | - Lazaros Oreopoulos
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
| | - Robert Wood
- Department of Atmospheric Sciences, University of Washington, Seattle, WA USA
| | - Huisheng Bian
- GESTAR-II, University of Maryland, Baltimore County, MD USA
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
| | - Katherine Breen
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
- GESTAR-II, Morgan State University, Baltimore, MD USA
| | - Mian Chin
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
| | - Hongbin Yu
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
| | - Donifan Barahona
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
| | - Kerry Meyer
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
| | - Steven Platnick
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD USA
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2
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Feingold G, Ghate VP, Russell LM, Blossey P, Cantrell W, Christensen MW, Diamond MS, Gettelman A, Glassmeier F, Gryspeerdt E, Haywood J, Hoffmann F, Kaul CM, Lebsock M, McComiskey AC, McCoy DT, Ming Y, Mülmenstädt J, Possner A, Prabhakaran P, Quinn PK, Schmidt KS, Shaw RA, Singer CE, Sorooshian A, Toll V, Wan JS, Wood R, Yang F, Zhang J, Zheng X. Physical science research needed to evaluate the viability and risks of marine cloud brightening. SCIENCE ADVANCES 2024; 10:eadi8594. [PMID: 38507486 PMCID: PMC10954212 DOI: 10.1126/sciadv.adi8594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 02/14/2024] [Indexed: 03/22/2024]
Abstract
Marine cloud brightening (MCB) is the deliberate injection of aerosol particles into shallow marine clouds to increase their reflection of solar radiation and reduce the amount of energy absorbed by the climate system. From the physical science perspective, the consensus of a broad international group of scientists is that the viability of MCB will ultimately depend on whether observations and models can robustly assess the scale-up of local-to-global brightening in today's climate and identify strategies that will ensure an equitable geographical distribution of the benefits and risks associated with projected regional changes in temperature and precipitation. To address the physical science knowledge gaps required to assess the societal implications of MCB, we propose a substantial and targeted program of research-field and laboratory experiments, monitoring, and numerical modeling across a range of scales.
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Affiliation(s)
| | | | - Lynn M. Russell
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | | | - Will Cantrell
- Michigan Technological University, Houghton, MI, USA
| | | | | | | | | | | | | | | | | | - Matthew Lebsock
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | - Yi Ming
- Boston College, Chestnut Hill, MA, USA
| | | | | | - Prasanth Prabhakaran
- NOAA Chemical Sciences Laboratory, Boulder, CO, USA
- CIRES, University of Colorado, Boulder, CO, USA
| | | | | | | | | | | | | | - Jessica S. Wan
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | | | - Fan Yang
- National Center for Atmospheric Research, Boulder, CO, USA
| | - Jianhao Zhang
- NOAA Chemical Sciences Laboratory, Boulder, CO, USA
- CIRES, University of Colorado, Boulder, CO, USA
| | - Xue Zheng
- Lawrence Livermore National Laboratory, Livermore, CA, USA
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3
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Yuan T, Song H, Wood R, Oreopoulos L, Platnick S, Wang C, Yu H, Meyer K, Wilcox E. Observational evidence of strong forcing from aerosol effect on low cloud coverage. SCIENCE ADVANCES 2023; 9:eadh7716. [PMID: 37939179 DOI: 10.1126/sciadv.adh7716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 10/04/2023] [Indexed: 11/10/2023]
Abstract
Aerosols cool Earth's climate indirectly by increasing low cloud brightness and their coverage (Cf), constituting the aerosol indirect forcing (AIF). The forcing partially offsets the greenhouse warming and positively correlates with the climate sensitivity. However, it remains highly uncertain. Here, we show direct observational evidence for strong forcing from Cf adjustment to increased aerosols and weak forcing from cloud liquid water path adjustment. We estimate that the Cf adjustment drives between 52% and 300% of additional forcing to the Twomey effect over the ocean and a total AIF of -1.1 ± 0.8 W m-2. The Cf adjustment follows a power law as a function of background cloud droplet number concentration, Nd. It thus depends on time and location and is stronger when Nd is low. Cf only increases substantially when background clouds start to drizzle, suggesting a role for aerosol-precipitation interactions. Our findings highlight the Cf adjustment as the key process for reducing the uncertainty of AIF and thus future climate projections.
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Affiliation(s)
- Tianle Yuan
- Goddard Earth Sciences Technology and Research (GESTAR) II, University of Maryland, Baltimore County, Baltimore, MD, USA
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD, USA
| | - Hua Song
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD, USA
- SSAI Inc., Lanham, MD, USA
| | - Robert Wood
- Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
| | - Lazaros Oreopoulos
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD, USA
| | - Steven Platnick
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD, USA
| | - Chenxi Wang
- Goddard Earth Sciences Technology and Research (GESTAR) II, University of Maryland, Baltimore County, Baltimore, MD, USA
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD, USA
| | - Hongbin Yu
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD, USA
| | - Kerry Meyer
- Sciences and Exploration Directorate, Goddard Space Flight Center, Greenbelt, MD, USA
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4
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Abstract
Ship tracks have long been studied as a clear manifestation of broader anthropogenic aerosol effects, but typically only in specific regions or for relatively short periods of time. Now, with the help of a machine-learning algorithm we have detected all of the tracks across the world’s oceans over two decades—more than 1 million in total. This allows us to determine where tracks are more likely to form and the sensitivity of clouds to such perturbations. Crucially, we see a sharp reduction in tracks due to the more stringent ship emission regulations since 2020. This constitutes clear evidence of a global cloud response to environmental regulations despite no such change being observed in other cloud properties. Global shipping accounts for 13% of global emissions of SO2, which, once oxidized to sulfate aerosol, acts to cool the planet both directly by scattering sunlight and indirectly by increasing the albedo of clouds. This cooling due to sulfate aerosol offsets some of the warming effect of greenhouse gasses and is the largest uncertainty in determining the change in the Earth’s radiative balance by human activity. Ship tracks—the visible manifestation of the indirect of effect of ship emissions on clouds as quasi-linear features—have long provided an opportunity to quantify these effects. However, they have been arduous to catalog and typically studied only in particular regions for short periods of time. Using a machine-learning algorithm to automate their detection we catalog more than 1 million ship tracks to provide a global climatology. We use this to investigate the effect of stringent fuel regulations introduced by the International Maritime Organization in 2020 on their global prevalence since then, while accounting for the disruption in global commerce caused by COVID-19. We find a marked, but clearly nonlinear, decline in ship tracks globally: An 80% reduction in SOx emissions causes only a 25% reduction in the number of tracks detected.
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5
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Finding the invisible traces of shipping in marine clouds. Nature 2022:10.1038/d41586-022-03026-7. [PMID: 36198815 DOI: 10.1038/d41586-022-03026-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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6
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Manshausen P, Watson-Parris D, Christensen MW, Jalkanen JP, Stier P. Invisible ship tracks show large cloud sensitivity to aerosol. Nature 2022; 610:101-106. [PMID: 36198778 PMCID: PMC9534750 DOI: 10.1038/s41586-022-05122-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 07/19/2022] [Indexed: 11/09/2022]
Abstract
Cloud reflectivity is sensitive to atmospheric aerosol concentrations because aerosols provide the condensation nuclei on which water condenses1. Increased aerosol concentrations due to human activity affect droplet number concentration, liquid water and cloud fraction2, but these changes are subject to large uncertainties3. Ship tracks, long lines of polluted clouds that are visible in satellite images, are one of the main tools for quantifying aerosol-cloud interactions4. However, only a small fraction of the clouds polluted by shipping show ship tracks5,6. Here we show that even when no ship tracks are visible in satellite images, aerosol emissions change cloud properties substantially. We develop a new method to quantify the effect of shipping on all clouds, showing a cloud droplet number increase and a more positive liquid water response when there are no visible tracks. We directly detect shipping-induced cloud property changes in the trade cumulus regions of the Atlantic, which are known to display almost no visible tracks. Our results indicate that previous studies of ship tracks were suffering from selection biases by focusing only on visible tracks from satellite imagery. The strong liquid water path response we find translates to a larger aerosol cooling effect on the climate, potentially masking a higher climate sensitivity than observed temperature trends would otherwise suggest.
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Affiliation(s)
- Peter Manshausen
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, UK.
| | - Duncan Watson-Parris
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, UK
| | | | | | - Philip Stier
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, UK
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7
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Xu B, Zhang G, Gustafsson Ö, Kawamura K, Li J, Andersson A, Bikkina S, Kunwar B, Pokhrel A, Zhong G, Zhao S, Li J, Huang C, Cheng Z, Zhu S, Peng P, Sheng G. Large contribution of fossil-derived components to aqueous secondary organic aerosols in China. Nat Commun 2022; 13:5115. [PMID: 36045131 PMCID: PMC9433442 DOI: 10.1038/s41467-022-32863-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 08/22/2022] [Indexed: 11/09/2022] Open
Abstract
Incomplete understanding of the sources of secondary organic aerosol (SOA) leads to large uncertainty in both air quality management and in climate change assessment. Chemical reactions occurring in the atmospheric aqueous phase represent an important source of SOA mass, yet, the effects of anthropogenic emissions on the aqueous SOA (aqSOA) are not well constrained. Here we use compound-specific dual-carbon isotopic fingerprints (δ13C and Δ14C) of dominant aqSOA molecules, such as oxalic acid, to track the precursor sources and formation mechanisms of aqSOA. Substantial stable carbon isotope fractionation of aqSOA molecules provides robust evidence for extensive aqueous-phase processing. Contrary to the paradigm that these aqSOA compounds are largely biogenic, radiocarbon-based source apportionments show that fossil precursors produced over one-half of the aqSOA molecules. Large fractions of fossil-derived aqSOA contribute substantially to the total water-soluble organic aerosol load and hence impact projections of both air quality and anthropogenic radiative forcing. Our findings reveal the importance of fossil emissions for aqSOA with effects on climate and air quality.
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Affiliation(s)
- Buqing Xu
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Gan Zhang
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China. .,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China.
| | - Örjan Gustafsson
- Department of Environment Science and the Bolin Centre for Climate Research, Stockholm University, Stockholm, 10691, Sweden.
| | - Kimitaka Kawamura
- Chubu Institute for Advanced Studies, Chubu University, Kasugai, 487-8501, Japan
| | - Jun Li
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - August Andersson
- Department of Environment Science and the Bolin Centre for Climate Research, Stockholm University, Stockholm, 10691, Sweden
| | - Srinivas Bikkina
- Chubu Institute for Advanced Studies, Chubu University, Kasugai, 487-8501, Japan.,CSIR-National Institute of Oceanography, Dona Paula, 403004, Goa, India
| | - Bhagawati Kunwar
- Chubu Institute for Advanced Studies, Chubu University, Kasugai, 487-8501, Japan
| | - Ambarish Pokhrel
- Chubu Institute for Advanced Studies, Chubu University, Kasugai, 487-8501, Japan.,Institute of Science and Technology, Tribhuvan University, Kathmandu, 44600, Nepal
| | - Guangcai Zhong
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Shizhen Zhao
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Jing Li
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Chen Huang
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Zhineng Cheng
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Sanyuan Zhu
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Pingan Peng
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Guoying Sheng
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.,CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
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8
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Dagan G, Stier P, Dingley B, Williams AIL. Examining the Regional Co-Variability of the Atmospheric Water and Energy Imbalances in Different Model Configurations-Linking Clouds and Circulation. JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS 2022; 14:e2021MS002951. [PMID: 35864947 PMCID: PMC9285806 DOI: 10.1029/2021ms002951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 03/22/2022] [Accepted: 05/08/2022] [Indexed: 06/15/2023]
Abstract
Clouds are a key player in the global climate system, affecting the atmospheric water and energy budgets, and they are strongly coupled to the large-scale atmospheric circulation. Here, we examine the co-variability of the atmospheric energy and water budget imbalances in three different global model configurations-radiative-convective equilibrium, aqua-planet, and global simulations with land. The gradual increase in the level of complexity of the model configuration enables an investigation of the effects of rotation, meridional temperature gradient, land-sea contrast, and seasonal cycle on the co-variability of the water and energy imbalances. We demonstrate how this co-variability is linked to both the large-scale tropical atmospheric circulation and to cloud properties. Hence, we propose a co-variability-based framework that connects cloud properties to the large-scale tropical circulation and climate system and is directly linked to the top-down constrains on the system-the water and energy budgets. In addition, we examine how the water and energy budget imbalances co-variability depends on the temporal averaging scale, and explain its dependency on how stationary the circulation is in the different model configurations. Finally, we demonstrate the effect of an idealized global warming and convective aggregation on this co-variability.
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Affiliation(s)
- Guy Dagan
- Fredy and Nadine Herrmann Institute of Earth SciencesHebrew UniversityJerusalemIsrael
| | - Philip Stier
- Department of Physics, Atmospheric, Oceanic and Planetary PhysicsUniversity of OxfordOxfordUK
| | - Beth Dingley
- Department of Physics, Atmospheric, Oceanic and Planetary PhysicsUniversity of OxfordOxfordUK
| | - Andrew I. L. Williams
- Department of Physics, Atmospheric, Oceanic and Planetary PhysicsUniversity of OxfordOxfordUK
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9
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Mansour K, Rinaldi M, Preißler J, Decesari S, Ovadnevaite J, Ceburnis D, Paglione M, Facchini MC, O'Dowd C. Phytoplankton Impact on Marine Cloud Microphysical Properties Over the Northeast Atlantic Ocean. JOURNAL OF GEOPHYSICAL RESEARCH. ATMOSPHERES : JGR 2022; 127:e2021JD036355. [PMID: 35860437 PMCID: PMC9285769 DOI: 10.1029/2021jd036355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 04/26/2022] [Accepted: 04/30/2022] [Indexed: 05/11/2023]
Abstract
The current understanding of the impact of natural cloud condensation nuclei (CCN) variability on cloud properties in marine air is low, thus contributing to climate prediction uncertainty. By analyzing cloud remote sensing observations (2009-2015) at Mace Head (west coast of Ireland), we show the oceanic biota impact on the microphysical properties of stratiform clouds over the Northeast Atlantic Ocean. During spring to summer (seasons of enhanced oceanic biological activity), clouds typically host a higher number of smaller droplets resulting from increased aerosol number concentration in the CCN relevant-size range. The induced increase in cloud droplet number concentration (+100%) and decrease in their radius (-14%) are comparable in magnitude to that generated by the advection of anthropogenically influenced air masses over the background marine boundary layer. Cloud water content and albedo respond to marine CCN perturbations with positive adjustments, making clouds brighter as the number of droplets increases. Cloud susceptibility to marine aerosols overlaps with a large variability of cloud macrophysical and optical properties primarily affected by the meteorological conditions. The above findings suggest the existence of a potential feedback mechanism between marine biota and the marine cloud-climate system.
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Affiliation(s)
- Karam Mansour
- Italian National Research Council ‐ Institute of Atmospheric Sciences and Climate (CNR‐ISAC)BolognaItaly
- Oceanography Department, Faculty of ScienceAlexandria UniversityAlexandriaEgypt
| | - Matteo Rinaldi
- Italian National Research Council ‐ Institute of Atmospheric Sciences and Climate (CNR‐ISAC)BolognaItaly
| | | | - Stefano Decesari
- Italian National Research Council ‐ Institute of Atmospheric Sciences and Climate (CNR‐ISAC)BolognaItaly
| | - Jurgita Ovadnevaite
- School of PhysicsRyan Institute's Centre for Climate and Air Pollution StudiesNational University of Ireland GalwayGalwayIreland
| | - Darius Ceburnis
- School of PhysicsRyan Institute's Centre for Climate and Air Pollution StudiesNational University of Ireland GalwayGalwayIreland
| | - Marco Paglione
- Italian National Research Council ‐ Institute of Atmospheric Sciences and Climate (CNR‐ISAC)BolognaItaly
| | - Maria C. Facchini
- Italian National Research Council ‐ Institute of Atmospheric Sciences and Climate (CNR‐ISAC)BolognaItaly
| | - Colin O'Dowd
- School of PhysicsRyan Institute's Centre for Climate and Air Pollution StudiesNational University of Ireland GalwayGalwayIreland
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10
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Christensen MW, Gettelman A, Cermak J, Dagan G, Diamond M, Douglas A, Feingold G, Glassmeier F, Goren T, Grosvenor DP, Gryspeerdt E, Kahn R, Li Z, Ma PL, Malavelle F, McCoy IL, McCoy DT, McFarquhar G, Mülmenstädt J, Pal S, Possner A, Povey A, Quaas J, Rosenfeld D, Schmidt A, Schrödner R, Sorooshian A, Stier P, Toll V, Watson-Parris D, Wood R, Yang M, Yuan T. Opportunistic experiments to constrain aerosol effective radiative forcing. ATMOSPHERIC CHEMISTRY AND PHYSICS 2022; 22:641-674. [PMID: 35136405 PMCID: PMC8819675 DOI: 10.5194/acp-22-641-2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Aerosol-cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be challenging when meteorological variability also drives both aerosol and cloud changes independently. Natural and anthropogenic aerosol perturbations from well-defined sources provide "opportunistic experiments" (also known as natural experiments) to investigate ACI in cases where causality may be more confidently inferred. These perturbations cover a wide range of locations and spatiotemporal scales, including point sources such as volcanic eruptions or industrial sources, plumes from biomass burning or forest fires, and tracks from individual ships or shipping corridors. We review the different experimental conditions and conduct a synthesis of the available satellite datasets and field campaigns to place these opportunistic experiments on a common footing, facilitating new insights and a clearer understanding of key uncertainties in aerosol radiative forcing. Cloud albedo perturbations are strongly sensitive to background meteorological conditions. Strong liquid water path increases due to aerosol perturbations are largely ruled out by averaging across experiments. Opportunistic experiments have significantly improved process-level understanding of ACI, but it remains unclear how reliably the relationships found can be scaled to the global level, thus demonstrating a need for deeper investigation in order to improve assessments of aerosol radiative forcing and climate change.
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Affiliation(s)
- Matthew W. Christensen
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- Atmospheric Science & Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99354, Washington, USA
| | | | - Jan Cermak
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research, Karlsruhe, Germany
- Karlsruhe Institute of Technology (KIT), Institute of Photogrammetry and Remote Sensing, Karlsruhe, Germany
| | - Guy Dagan
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Michael Diamond
- Department of Atmospheric Sciences, University of Washington, Seattle, USA
- NOAA Chemical Sciences Laboratory (CSL), Boulder, Colorado, USA
- Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado, USA
| | - Alyson Douglas
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
| | - Graham Feingold
- NOAA Chemical Sciences Laboratory (CSL), Boulder, Colorado, USA
| | - Franziska Glassmeier
- Department Geoscience and Remote Sensing, Delft University of Technology, P.O. Box 5048, 2600GA Delft, the Netherlands
| | - Tom Goren
- Institute for Meteorology, Universität Leipzig, Leipzig, Germany
| | - Daniel P. Grosvenor
- National Centre for Atmospheric Sciences, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK
| | - Edward Gryspeerdt
- Space and Atmospheric Physics Group, Imperial College London, London, UK
| | - Ralph Kahn
- Earth Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Zhanqing Li
- Department of Atmospheric and Oceanic Science, University of Maryland, College Park, USA
| | - Po-Lun Ma
- Atmospheric Science & Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99354, Washington, USA
| | - Florent Malavelle
- Met Office, Atmospheric Dispersion and Air Quality, Fitzroy Rd, Exeter, EX1 3PB, UK
| | - Isabel L. McCoy
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
- Cooperative Programs for the Advancement of Earth System Science (CPAESS), University Corporation for Atmospheric Research, Boulder, CO, USA
| | - Daniel T. McCoy
- Department of Atmospheric Sciences, University of Wyoming, Laramie, USA
| | - Greg McFarquhar
- Cooperative Institute for Severe and High Impact Weather Research and Operations (CIWRO) and School of Meteorology, University of Oklahoma, Norman, OK, USA
- School of Meteorology, University of Oklahoma, Norman, OK, USA
| | - Johannes Mülmenstädt
- Atmospheric Science & Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99354, Washington, USA
| | - Sandip Pal
- Department of Geosciences, Texas Tech University, Lubbock, TX, USA
| | - Anna Possner
- Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Adam Povey
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- National Centre for Earth Observation, University of Oxford, Oxford, OX1 3PU, UK
| | - Johannes Quaas
- Institute for Meteorology, Universität Leipzig, Leipzig, Germany
| | - Daniel Rosenfeld
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Anja Schmidt
- Department of Geography, University of Cambridge, Cambridge, UK
- Department of Chemistry, University of Cambridge, Cambridge, UK
| | | | - Armin Sorooshian
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA
- Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, USA
| | - Philip Stier
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
| | - Velle Toll
- Institute of Physics, University of Tartu, Tartu, Estonia
| | - Duncan Watson-Parris
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
| | - Robert Wood
- Department of Atmospheric Sciences, University of Washington, Seattle, USA
| | - Mingxi Yang
- Plymouth Marine Laboratory, Prospect Place, Plymouth, PL1 3DH, UK
| | - Tianle Yuan
- Joint Center for Earth Systems Technologies, University of Maryland, Baltimore County, Baltimore, MD, USA
- Earth Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
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