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6. PalVol v1: a proxy-based semi-stochastic ensemble reconstruction of volcanic stratospheric sulfur injection for the last glacial cycle (140 000–50 BP)

Author

Schindlbeck-Belo, Julie Christin, Toohey, Matthew, Jegen, Marion, Kutterolf, Steffen, Rehfeld, Kira, Schindlbeck-Belo, Julie Christin, Toohey, Matthew, Jegen, Marion, Kutterolf, Steffen, and Rehfeld, Kira

Abstract

Perturbations in stratospheric aerosol due to explosive volcanic eruptions are a primary contributor to natural climate variability. Observations of stratospheric aerosol are available for the past decades, and information from ice cores has been used to derive estimates of stratospheric sulfur injections and aerosol optical depth over the Holocene (approximately 10 000 BP to present) and into the last glacial period, extending back to 60 000 BP. Tephra records of past volcanism, compared to ice cores, are less complete but extend much further into the past. To support model studies of the potential impacts of explosive volcanism on climate variability across timescales, we present here an ensemble reconstruction of volcanic stratospheric sulfur injection (VSSI) over the last 140 000 years that is based primarily on terrestrial and marine tephra records. VSSI values are computed as a simple function of eruption magnitude based on VSSI estimates from ice cores and satellite observations for identified eruptions. To correct for the incompleteness of the tephra record, we include stochastically generated synthetic eruptions assuming a constant background eruption frequency from the ice core Holocene record. While the reconstruction often differs from ice core estimates for specific eruptions due to uncertainties in the data used and reconstruction method, it shows good agreement with an ice-core-based VSSI reconstruction in terms of millennial-scale cumulative VSSI variations over the Holocene. The PalVol reconstruction provides a new basis to test the contributions of forced vs. unforced natural variability to the spectrum of climate and the mechanisms leading to abrupt transitions in the palaeoclimate record with low- to high-complexity climate models. The PalVol volcanic forcing reconstruction is available at https://doi.org/10.26050/WDCC/PalVolv1 (Toohey and Schindlbeck-Belo, 2023).

Published
2024
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7. Why does stratospheric aerosol forcing strongly cool the warm pool?

Author

Günther, Moritz, Schmidt, Hauke, Timmreck, Claudia, and Toohey, Matthew

Subjects
STRATOSPHERIC aerosols, OZONE layer, SURFACE forces, SURFACE temperature, CARBON dioxide, AEROSOLS
Abstract

Previous research has shown that stratospheric aerosol causes only a small temperature change per unit forcing because they produce stronger cooling in the tropical Indian Ocean and the western Pacific Ocean than in the global mean. The enhanced temperature change in this so-called "warm-pool" region activates strongly negative local and remote feedbacks, which dampen the global mean temperature response. This paper addresses the question of why stratospheric aerosol forcing affects warm-pool temperatures more strongly than CO 2 forcing, using idealized MPI-ESM simulations. We show that the aerosol's enhanced effective forcing at the top of the atmosphere (TOA) over the warm pool contributes to the warm-pool-intensified temperature change but is not sufficient to explain the effect. Instead, the pattern of surface effective forcing, which is substantially different from the effective forcing at the TOA, is more closely linked to the temperature pattern. Independent of surface temperature changes, the aerosol heats the tropical stratosphere, accelerating the Brewer–Dobson circulation. The intensified Brewer–Dobson circulation exports additional energy from the tropics to the extratropics, which leads to a particularly strong negative forcing at the tropical surface. These results show how forced circulation changes can affect the climate response by altering the surface forcing pattern. Furthermore, they indicate that the established approach of diagnosing effective forcing at the TOA is useful for global means, but a surface perspective on the forcing must be adopted to understand the evolution of temperature patterns. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Initial atmospheric conditions control transport of volcanic volatiles, forcing and impacts.

Author

Zhuo, Zhihong, Fuglestvedt, Herman F., Toohey, Matthew, and Krüger, Kirstin

Subjects
WEATHER, VOLCANIC eruptions, SULFATE aerosols, OZONE layer depletion, SURFACE temperature
Abstract

Volcanic eruptions impact the climate and environment. The volcanic forcing is determined by eruption source parameters, including the mass and composition of volcanic volatiles, eruption season, eruption latitude, and injection altitude. Moreover, initial atmospheric conditions of the climate system play an important role in shaping the volcanic forcing and response. However, our understanding of the combination of these factors, the distinctions between tropical and extratropical volcanic eruptions, and the co-injection of sulfur and halogens remains limited. Here, we perform ensemble simulations of volcanic eruptions at 15 and 64° N in January, injecting 17 Mt of SO 2 together with HCl and HBr at 24 km altitude. Our findings reveal that initial atmospheric conditions control the transport of volcanic volatiles from the first month and modulate the subsequent latitudinal distribution of sulfate aerosols and halogens. This results in different volcanic forcing, surface temperature and ozone responses over the globe and Northern Hemisphere extratropics (NHET) among the model ensemble members with different initial atmospheric conditions. NH extratropical eruptions exhibit a larger NHET mean volcanic forcing, surface cooling and ozone depletion compared with tropical eruptions. However, tropical eruptions lead to more prolonged impacts compared with NH extratropical eruptions, both globally and in the NHET. The sensitivity of volcanic forcing to varying eruption source parameters and model dependency is discussed, emphasizing the need for future multi-model studies to consider the influence of initial conditions and eruption source parameters on volcanic forcing and subsequent impacts. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Initial conditions control transport of volcanic volatiles, forcing and impacts.

Author

Zhihong Zhuo, Fuglestvedt, Herman F., Toohey, Matthew, and Krüger, Kirstin

Abstract

Volcanic eruptions impact the climate and environment. The volcanic forcing is determined by eruption source parameters, including mass and composition of volcanic volatiles, eruption season, eruption latitude and injection altitude. Moreover, initial conditions of the climate system play an important role in shaping the volcanic response. However, our understanding of the combination of these factors, the distinctions between tropical and extratropical volcanic eruptions and the co-injection of sulfur and halogens remains limited. Here, we perform ensemble simulations of volcanic eruptions at 15° N and 64° N in January, injecting 17 Mt of SO2 together with HCl and HBr at 24 km altitude, considering different initial conditions of the El Niño-Southern Oscillation, Quasi-Biennial Oscillation, and polar vortex. Our findings reveal that initial conditions control the transport of volcanic volatiles from the first month and modulate the subsequent latitudinal distribution of sulfate aerosols and halogens. This results in different volcanic forcing, surface temperature and ozone responses over the globe and Northern Hemisphere Extratropics (NHET) among the model ensemble members with different initial conditions. NH extratropical eruptions exhibit a larger NHET mean volcanic forcing, surface cooling and ozone depletion compared to tropical eruptions. However, tropical eruptions lead to more prolonged impacts compared to NH extratropical eruptions, both globally and in the NHET. The sensitivity of volcanic forcing to varying eruption source parameters and model dependency is discussed, emphasizing the need for future multi-model studies to consider the influence of initial conditions and eruption source parameters on volcanic forcing and subsequent impacts. [ABSTRACT FROM AUTHOR]

Published
2023
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18. Initial conditions control transport of volcanic volatiles, forcing and impacts.

Author

Zhuo, Zhihong, Fuglestvedt, Herman F., Toohey, Matthew, and Krüger, Kirstin

Subjects
VOLCANIC eruptions, SULFATE aerosols, POLAR vortex, OZONE layer depletion, SURFACE temperature, HALOGENS
Abstract

Volcanic eruptions impact the climate and environment. The volcanic forcing is determined by eruption source parameters, including mass and composition of volcanic volatiles, eruption season, eruption latitude and injection altitude. Moreover, initial conditions of the climate system play an important role in shaping the volcanic response. However, our understanding of the combination of these factors, the distinctions between tropical and extratropical volcanic eruptions and the co–injection of sulfur and halogens remains limited. Here, we perform ensemble simulations of volcanic eruptions at 15° N and 64° N in January, injecting 17 Mt of SO2 together with HCl and HBr at 24 km altitude, considering different initial conditions of the El Niño–Southern Oscillation, Quasi–Biennial Oscillation, and polar vortex. Our findings reveal that initial conditions control the transport of volcanic volatiles from the rst month and modulate the subsequent latitudinal distribution of sulfate aerosols and halogens. This results in different volcanic forcing, surface temperature and ozone responses over the globe and Northern Hemisphere Extratropics (NHET) among the model ensemble members with different initial conditions. NH extratropical eruptions exhibit a larger NHET mean volcanic forcing, surface cooling and ozone depletion compared to tropical eruptions. However, tropical eruptions lead to more prolonged impacts compared to NH extratropical eruptions, both globally and in the NHET. The sensitivity of volcanic forcing to varying eruption source parameters and model dependency is discussed, emphasizing the need for future multi–model studies to consider the influence of initial conditions and eruption source parameters on volcanic forcing and subsequent impacts. [ABSTRACT FROM AUTHOR]

Published
2023
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21. PalVol v1: A proxy-based semi-stochastic ensemble reconstruction of volcanic stratospheric sulfur injection for the last glacial cycle (130,000–50 BP)

Author

Schindlbeck-Belo, Julie Christin, Toohey, Matthew, Jegen, Marion, Kutterolf, Steffen, Rehfeld, Kira, Schindlbeck-Belo, Julie Christin, Toohey, Matthew, Jegen, Marion, Kutterolf, Steffen, and Rehfeld, Kira

Abstract

Perturbations in stratospheric aerosol due to explosive volcanic eruptions are a primary contributor to natural climate variability. Observations of stratospheric aerosol are available for the past decades, and information from ice cores has been used to derive estimates of stratospheric sulfur injections and aerosol optical depth over the Holocene (approximately 10,000 BP to present) and into the last glacial period, extending back to 60,000 BP. Tephra records of past volcanism, compared to ice cores, are less complete, but extend much further into the past. To support model studies of the potential impacts of explosive volcanism on climate variability over across timescales, we present here an ensemble reconstruction of volcanic stratospheric sulfur injection (VSSI) over the last 130,000 years that is based primarily on terrestrial and marine tephra records. VSSI values are computed as a simple function of eruption magnitude, based on VSSI estimates from ice cores and satellite observations for identified eruptions. To correct for the incompleteness of the tephra record we include stochastically generated synthetic eruptions, assuming a constant background eruption frequency from the ice core Holocene record. While the reconstruction often differs from ice core estimates for specific eruptions due to uncertainties in the data used and reconstruction method, it shows good agreement with an ice core based VSSI reconstruction in terms of millennial-scale cumulative VSSI variations over the Holocene. The PalVol reconstruction provides a new basis to test the contributions of forced vs. unforced natural variability to the spectrum of climate, and the mechanisms leading to abrupt transitions in the palaeoclimate record with low-to-high complexity climate models. The PalVol volcanic forcing reconstruction is available at https://doi.org/10.26050/WDCC/PalVolv1 (Toohey, Schindlbeck-Belo, 2023).

Published
2023
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22. On the lack of stratospheric dynamical variability in low-top versions of the CMIP5 models

Author

Charlton-Perez, Andrew J., Baldwin, Mark P., Birner, Thomas, Black, Robert X., Butler, Amy H., Calvo Fernández, Natalia, Davis, Nicholas A., Gerber, Edwin P., Gillett, Nathan, Hardiman, Steven, Kim, Junsu, Krüger, Kirstin, Lee, Yun-Young, Manzini, Elisa, McDaniel, Brent A., Polvani, Lorenzo, Reichler, Thomas, Shaw, Tiffany A., Sigmond, Michael, Son, Seok-Woo, Toohey, Matthew, Wilcox, Laura, Yoden, Shigeo, Christiansen, Bo, Lott, François, Shindell, Drew, Yukimoto, Seiji, Watanabe, Shingo, Charlton-Perez, Andrew J., Baldwin, Mark P., Birner, Thomas, Black, Robert X., Butler, Amy H., Calvo Fernández, Natalia, Davis, Nicholas A., Gerber, Edwin P., Gillett, Nathan, Hardiman, Steven, Kim, Junsu, Krüger, Kirstin, Lee, Yun-Young, Manzini, Elisa, McDaniel, Brent A., Polvani, Lorenzo, Reichler, Thomas, Shaw, Tiffany A., Sigmond, Michael, Son, Seok-Woo, Toohey, Matthew, Wilcox, Laura, Yoden, Shigeo, Christiansen, Bo, Lott, François, Shindell, Drew, Yukimoto, Seiji, and Watanabe, Shingo

Abstract

© 2013 American Geophysical Union. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups for producing and making available the model output listed in Table 1. For CMIP the U.S. Department of Energy's Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. A. J. C.-P. and L. J. W. were supported by an National Centre for Atmospheric Science CMIP5 grant. M. P. B. was funded by NSF under the US CLIVAR program and the Office of Polar Programs. T. B. and N. A. D. acknowledge support by the U.S. National Science Foundation. The research efforts of R. X. B., B. A. M. & Y.-Y. L. were conducted under support by the U.S. Department of Energy, Office of Biological and Environmental Research, Award No. DE-FOA000024 and by the National Science Foundation Grant, ARC-1107384. N. C. was supported by the Spanish Ministry of Science and Innovation (MCINN) through the CGL2008-05968-C02-01 project. E. P. G. was supported by the National Science Foundation. The work of M. T. and K. K. contributes to the BMBF joint research project MiKlip within the project ALARM through the grant 01LP1130B. The work of S. C. H. was supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). We also acknowledge the European Commission's 7th Framework Programme, under Grant Agreement number 226520, COMBINE project which supplied some data not available from the CMIP5 archive. We also thank Gerard Devine (NCAS-CMS) for help with accessing and parsing meta-data information from the models., We describe the main differences in simulations of stratospheric climate and variability by models within the fifth Coupled Model Intercomparison Project (CMIP5) that have a model top above the stratopause and relatively fine stratospheric vertical resolution (high-top), and those that have a model top below the stratopause (low-top). Although the simulation of mean stratospheric climate by the two model ensembles is similar, the low-top model ensemble has very weak stratospheric variability on daily and interannual time scales. The frequency of major sudden stratospheric warming events is strongly underestimated by the low-top models with less than half the frequency of events observed in the reanalysis data and high-top models. The lack of stratospheric variability in the low-top models affects their stratosphere-troposphere coupling, resulting in short-lived anomalies in the Northern Annular Mode, which do not produce long-lasting tropospheric impacts, as seen in observations. The lack of stratospheric variability, however, does not appear to have any impact on the ability of the low-top models to reproduce past stratospheric temperature trends. We find little improvement in the simulation of decadal variability for the high-top models compared to the low-top, which is likely related to the fact that neither ensemble produces a realistic dynamical response to volcanic eruptions., National Centre for Atmospheric Science, NSF under the US CLIVAR program, U.S. National Science Foundation, U.S. Department of Energy, Office of Biological and Environmental Research, National Science Foundation, Spanish Ministry of Science and Innovation (MCINN), National Science Foundation, BMBF, Joint DECC/Defra Met Office Hadley Centre Climate Programme, European Commission, NSF under Office of Polar Program, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

30. Multi-model Comparison of the Volcanic Sulfate Deposition from the 1815 Eruption of Mt. Tambora

Author

Marshall, Lauren, Schmidt, Anja, Toohey, Matthew, Carslaw, Ken S, Mann, Graham W, Sigl, Michael, Khodri, Myriam, Timmreck, Claudia, Zanchettin, Davide, Ball, William T, Bekki, Slimane, Brooke, James S. A, Dhomse, Sandip, Johnson, Colin, Lamarque, Jean-Francois, LeGrande, Allegra N, Mills, Michael J, Niemeier, Ulrike, Pope, James O, Poulain, Virginie, Robock, Alan, Rozanov, Eugene, Stenke, Andrea, Sukhodolov, Timofei, Tilmes, Simone, Tsigaridis, Kostas, and Tummon, Fiona

Subjects
Geophysics
Abstract

The eruption of Mt. Tambora in 1815 was the largest volcanic eruption of the past 500 years. The eruption had significant climatic impacts, leading to the 1816 "year without a summer", and remains a valuable event from which to understand the climatic effects of large stratospheric volcanic sulfur dioxide injections. The eruption also resulted in one of the strongest and most easily identifiable volcanic sulfate signals in polar ice cores, which are widely used to reconstruct the timing and atmospheric sulfate loading of past eruptions. As part of the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP), five state-of-the-art global aerosol models simulated this eruption. We analyze both simulated background (no Tambora) and volcanic (with Tambora) sulfate deposition to polar regions and compare to ice core records. The models simulate overall similar patterns of background sulfate deposition, although there are differences in regional details and magnitude. However, the volcanic sulfate deposition varies considerably between the models with differences in timing, spatial pattern and magnitude. Mean simulated deposited sulfate on Antarctica ranges from 19 to 264 kgkm-2 and on Greenland from 31 to 194 kgkm-2, as compared to the mean ice-core derived estimates of roughly 50 kgkm-2 for both Greenland and Antarctica. The ratio of the hemispheric atmospheric sulfate aerosol burden after the eruption to the average ice sheet deposited sulfate varies between models by up to a factor of 15. Sources of this inter-model variability include differences in both the formation and the transport of sulfate aerosol. Our results suggest that deriving relationships between sulfate deposited on ice sheets and atmospheric sulfate burdens from model simulations may be associated with greater uncertainties than previously thought.

Published
2018
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33. The 852/3 CE Mount Churchill eruption: examining the potential climatic and societal impacts and the timing of the Medieval Climate Anomaly in the North Atlantic region

Author

Mackay, Helen, primary, Plunkett, Gill, additional, Jensen, Britta J. L., additional, Aubry, Thomas J., additional, Corona, Christophe, additional, Kim, Woon Mi, additional, Toohey, Matthew, additional, Sigl, Michael, additional, Stoffel, Markus, additional, Anchukaitis, Kevin J., additional, Raible, Christoph, additional, Bolton, Matthew S. M., additional, Manning, Joseph G., additional, Newfield, Timothy P., additional, Di Cosmo, Nicola, additional, Ludlow, Francis, additional, Kostick, Conor, additional, Yang, Zhen, additional, Coyle McClung, Lisa, additional, Amesbury, Matthew, additional, Monteath, Alistair, additional, Hughes, Paul D. M., additional, Langdon, Pete G., additional, Charman, Dan, additional, Booth, Robert, additional, Davies, Kimberley L., additional, Blundell, Antony, additional, and Swindles, Graeme T., additional

Published
2022
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34. Temperature and precipitation distribution changes in response to global warming – results from transient simulations of the Last Deglaciation from a hierarchy of climate models

Author

Ziegler, Elisa, primary, Wirths, Christian, additional, Andres, Heather, additional, Gregoire, Lauren, additional, Ivanovic, Ruza, additional, Kapsch, Marie-Luise, additional, Kutterolf, Steffen, additional, Mikolajewicz, Uwe, additional, Schindlbeck-Belo, Julie Christin, additional, Toohey, Matthew, additional, Valdes, Paul J., additional, Weitzel, Nils, additional, and Rehfeld, Kira, additional

Published
2022
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35. Effects of forcing differences and initial conditions on inter-model agreement in the VolMIP volc-pinatubo-full experiment

Author

Zanchettin, Davide, primary, Timmreck, Claudia, additional, Khodri, Myriam, additional, Schmidt, Anja, additional, Toohey, Matthew, additional, Abe, Manabu, additional, Bekki, Slimane, additional, Cole, Jason, additional, Fang, Shih-Wei, additional, Feng, Wuhu, additional, Hegerl, Gabriele, additional, Johnson, Ben, additional, Lebas, Nicolas, additional, LeGrande, Allegra N., additional, Mann, Graham W., additional, Marshall, Lauren, additional, Rieger, Landon, additional, Robock, Alan, additional, Rubinetti, Sara, additional, Tsigaridis, Kostas, additional, and Weierbach, Helen, additional

Published
2022
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36. The 853 CE Mount Churchill eruption: examining the potential climatic and societal impacts and the timing of the Medieval Climate Anomaly in the North Atlantic Region

Author

Mackay, Helen, Plunkett, Gill, Jensen, Britta, Aubry, Thomas, Corona, Christophe, Kim, Woon Mi, Toohey, Matthew, Sigl, Michael, Stoffel, Markus, Anchukaitis, Kevin, Raible, Christoph, Bolton, Matthew, Manning, Joesph, Newfield, Timothy, Di Cosmo, Nicola, Ludlow, Francis, Kostick, Conor, Yang, Zhen, Coyle McClung, Lisa, Amesbury, Matthew, Monteath, Alistair, Hughes, Paul, Langdon, Pete, Charman, Dan, Booth, Robert, Davies, Kimberley, Blundell, Antony, and Swindles, Graeme

Abstract

The 852/3 CE eruption of Mount Churchill, Alaska, was one of the largest first-millennium volcanic events, with a magnitude of 6.7 (VEI 6) and a tephra volume of 39.4–61.9 km3 (95 % confidence). The spatial extent of the ash fallout from this event is considerable and the cryptotephra (White River Ash east; WRAe) extends as far as Finland and Poland. Proximal ecosystem and societal disturbances have been linked with this eruption; however, wider eruption impacts on climate and society are unknown. Greenland ice core records show that the eruption occurred in winter 852/3 ± 1 CE and that the eruption is associated with a relatively moderate sulfate aerosol loading but large abundances of volcanic ash and chlorine. Here we assess the potential broader impact of this eruption using palaeoenvironmental reconstructions, historical records and climate model simulations. We also use the fortuitous timing of the 852/3 CE Churchill eruption and its extensively widespread tephra deposition of the White River Ash (east) (WRAe) to examine the climatic expression of the warm Medieval Climate Anomaly period (MCA; ca. 950–1250 CE) from precisely linked peatlands in the North Atlantic region. The reconstructed climate forcing potential of the 852/3 CE Churchill eruption is moderate compared with the eruption magnitude, but tree-ring-inferred temperatures report a significant atmospheric cooling of 0.8 ∘C in summer 853 CE. Modelled climate scenarios also show a cooling in 853 CE, although the average magnitude of cooling is smaller (0.3 ∘C). The simulated spatial patterns of cooling are generally similar to those generated using the tree-ring-inferred temperature reconstructions. Tree-ring-inferred cooling begins prior to the date of the eruption suggesting that natural internal climate variability may have increased the climate system's susceptibility to further cooling. The magnitude of the reconstructed cooling could also suggest that the climate forcing potential of this eruption may be underestimated, thereby highlighting the need for greater insight into, and consideration of, the role of halogens and volcanic ash when estimating eruption climate forcing potential. Precise comparisons of palaeoenvironmental records from peatlands across North America and Europe, facilitated by the presence of the WRAe isochron, reveal no consistent MCA signal. These findings contribute to the growing body of evidence that characterises the MCA hydroclimate as time-transgressive and heterogeneous rather than a well-defined climatic period. The presence of the WRAe isochron also demonstrates that no long-term (multidecadal) climatic or societal impacts from the 852/3 CE Churchill eruption were identified beyond areas proximal to the eruption. Historical evidence in Europe for subsistence crises demonstrate a degree of temporal correspondence on interannual timescales, but similar events were reported outside of the eruption period and were common in the 9th century. The 852/3 CE Churchill eruption exemplifies the difficulties of identifying and confirming volcanic impacts for a single eruption, even when the eruption has a small age uncertainty.

Published
2022
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42. The 852/3 CE Mount Churchill eruption: examining the potential climatic and societal impacts and the timing of the Medieval Climate Anomaly in the North Atlantic Region

Author

Mackay, Helen, primary, Plunkett, Gill, additional, Jensen, Britta, additional, Aubry, Thomas, additional, Corona, Christophe, additional, Kim, Woon Mi, additional, Toohey, Matthew, additional, Sigl, Michael, additional, Stoffel, Markus, additional, Anchukaitis, Kevin, additional, Raible, Christoph, additional, Bolton, Matthew, additional, Manning, Joesph, additional, Newfield, Timothy, additional, Di Cosmo, Nicola, additional, Ludlow, Francis, additional, Kostick, Conor, additional, Yang, Zhen, additional, Coyle McClung, Lisa, additional, Amesbury, Matthew, additional, Monteath, Alistair, additional, Hughes, Paul, additional, Langdon, Pete, additional, Charman, Dan, additional, Booth, Robert, additional, Davies, Kimberley, additional, Blundell, Antony, additional, and Swindles, Graeme, additional

Published
2021
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44. How Did Climate and Humans Respond to Past Volcanic Eruptions?

Author

Toohey, Matthew, Ludlow, Francis, and Legrande, Allegra N

Subjects
Meteorology And Climatology
Abstract

To predict and prepare for future climate change, scientists are striving to understand how global-scale climatic change manifests itself on regional scales and also how societies adapt or don't to sometimes subtle and complex climatic changes. In this regard, the strongest volcanic eruptions of the past are powerful test cases, showcasing how the broad climate system responds to sudden changes in radiative forcing and how societies have responded to the resulting climatic shocks. These issues were at the heart of the inaugural workshop of the Volcanic Impacts on Climate and Society (VICS) Working Group, convened in June 2016 at the Lamont-Doherty Earth Observatory of Columbia University in Palisades, N.Y. The 3-day meeting gathered approximately 50 researchers, who presented work intertwining the history of volcanic eruptions and the physical processes that connect eruptions with human and natural systems on a global scale.

Published
2016
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45. The Model Intercomparison Project on the Climatic Response to Volcanic Forcing (VolMIP): Experimental Design and Forcing Input Data for CMIP6

Author

Zanchettin, Davide, Khodri, Myriam, Timmreck, Claudia, Toohey, Matthew, Schmidt, Anja, Gerber, Edwin P, Hegerl, Gabriele, Robock, Alan, Pausata, Francesco, Ball, William T, Bauer, Susanne E, LeGrande, Allegra N, and Tsigaridis, Kostas

Subjects
Meteorology And Climatology
Abstract

The enhancement of the stratospheric aerosol layer by volcanic eruptions induces a complex set of responses causing global and regional climate effects on a broad range of timescales. Uncertainties exist regarding the climatic response to strong volcanic forcing identified in coupled climate simulations that contributed to the fifth phase of the Coupled Model Intercomparison Project (CMIP5). In order to better understand the sources of these model diversities, the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) has defined a coordinated set of idealized volcanic perturbation experiments to be carried out in alignment with the CMIP6 protocol. VolMIP provides a common stratospheric aerosol data set for each experiment to minimize differences in the applied volcanic forcing. It defines a set of initial conditions to assess how internal climate variability contributes to determining the response. VolMIP will assess to what extent volcanically forced responses of the coupled ocean-atmosphere system are robustly simulated by state-of-the-art coupled climate models and identify the causes that limit robust simulated behavior, especially differences in the treatment of physical processes. This paper illustrates the design of the idealized volcanic perturbation experiments in the VolMIP protocol and describes the common aerosol forcing input data sets to be used.

Published
2016
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46. Stratospheric Aerosol--Observations, Processes, and Impact on Climate

Author

Kresmer, Stefanie, Thomason, Larry W, von Hobe, Marc, Hermann, Markus, Deshler, Terry, Timmreck, Claudia, Toohey, Matthew, Stenke, Andrea, Schwarz, Joshua P, Weigel, Ralf, Fueglistaler, Stephan, Prata, Fred J, Vernier, Jean-Paul, Schlager, Hans, Barnes, John E, Antuna-Marrero, Juan-Carlos, Fairlie, Duncan, Palm, Mathias, Mahieu, Emmanuel, Notholt, Justus, Rex, Markus, Bingen, Christine, Vanhellemont, Filip, Bourassa, Adam, Plane, John M. C, Klocke, Daniel, Carn, Simon A, Clarisse, Lieven, Trickl, Thomas, Neeley, Ryan, James, Alexander D, Rieger, Landon, Wilson, James C, and Meland, Brian

Subjects
Meteorology And Climatology
Abstract

Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfatematter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes.

Published
2016
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47. Future global climate: scenario-based projections and near-term information

Author

Lee, June-Yi, Marotzke, Jochem, Bala, Govindasamy, Cao, Long, Corti, Susanna, Dunne, John P., Engelbrecht, Francois, Fischer, Erich, Fyfe, John C., Jones, Christopher, Maycock, Amanda, Mutemi, Joseph, Ndiaye, Ousmane, Panickal, Swapna, Zhou, Tianjun, Milinski, Sebastian, Yun, Kyung-Sook, Armour, Kyle, Bellouin, Nicolas, Bethke, Ingo, Byrne, Michael P., Cassou, Christophe, Chen, Deliang, Cherchi, Annalisa, Christensen, Hannah M., Connors, Sarah L., Di Luca, Alejandro, Drijfhout, Sybren S., Fletcher, Christopher G., Forster, Piers, Garcia-Serrano, Javier, Gillett, Nathan P., Kaufmann, Darrell S., Keller, David P., Kravitz, Ben, Li, Hongmei, Liang, Yongxiao, MacDougall, Andrew H., Malinina, Elizaveta, Menary, Matthew, Merryfield, William J., Min, Seung-Ki, Nicholls, Zebedee R. J., Notz, Dirk, Pearson, Brodie, Priestley, Matthew D. K., Quaas, Johannes, Ribes, Aurelien, Ruane, Alex C., Sallee, Jean-Baptiste, Sanchez-Gomez, Emilia, Seneviratne, Sonia I., Slangen, Aimee B. A., Smith, Chris, Stuecker, Malte F., Swaminathan, Ranjini, Thorne, Peter W., Tokarska, Katarzyna B., Toohey, Matthew, Turner, Andrew, Volpi, Danila, Xiao, Cunde, Zappa, Giuseppe, Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S. L., Pean, C., Berger, S., Caud, N., Chen, Y., Goldfarb, L., Gomis, M. I., Huang, M., Leitzell, K., Lonnoy, E., Matthews, J. B. R., Maycock, T. K., Waterfield, T., Yelekçi, O., Yu, R., and Zhou, B.

Published
2021

48. Supplementary material to "Effects of forcing differences and initial conditions on inter-model agreement in the VolMIP volc-pinatubo-full experiment"

Author

Zanchettin, Davide, primary, Timmreck, Claudia, additional, Khodri, Myriam, additional, Schmidt, Anja, additional, Toohey, Matthew, additional, Abe, Manabu, additional, Bekki, Slimane, additional, Cole, Jason, additional, Fang, Shih-Wei, additional, Feng, Wuhu, additional, Hegerl, Gabriele, additional, Johnson, Ben, additional, Lebas, Nicolas, additional, LeGrande, Allegra N., additional, Mann, Graham W., additional, Marshall, Lauren, additional, Rieger, Landon, additional, Robock, Alan, additional, Rubinetti, Sara, additional, Tsigaridis, Kostas, additional, and Weierbach, Helen, additional

Published
2021
Full Text
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49. Effects of forcing differences and initial conditions on inter-model agreement in the VolMIP volc-pinatubo-full experiment

Author

Zanchettin, Davide, primary, Timmreck, Claudia, additional, Khodri, Myriam, additional, Schmidt, Anja, additional, Toohey, Matthew, additional, Abe, Manabu, additional, Bekki, Slimane, additional, Cole, Jason, additional, Fang, Shih-Wei, additional, Feng, Wuhu, additional, Hegerl, Gabriele, additional, Johnson, Ben, additional, Lebas, Nicolas, additional, LeGrande, Allegra N., additional, Mann, Graham W., additional, Marshall, Lauren, additional, Rieger, Landon, additional, Robock, Alan, additional, Rubinetti, Sara, additional, Tsigaridis, Kostas, additional, and Weierbach, Helen, additional

Published
2021
Full Text
View/download PDF

50. Overview and update of the SPARC Data Initiative:\ud comparison of stratospheric composition\ud measurements from satellite limb sounders

Author

Hegglin, Michaela I., Tegtmeier, Susann, Anderson, John, Bourassa, Adam E., Brohede, Samuel, Degenstein, Doug, Froidevaux, Lucien, Funke, Bernd, Gille, John, Kasai, Yasuko, Kyrola, Erkki T., Lumpe, Jerry, Murtagh, Donal, Neu, Jessica L., Perot, Kristell, Remsberg, Ellis E., Rozanov, Alexei, Toohey, Matthew, Urban, Joachim, von Clarmann, Thomas, Walker, Kaley A., Wang, Hsiang-Jui, Arosio, Carlo, Damadeo, Robert, Fuller, Ryan A., Lingenfelser, Gretchen, McLinden, Christopher, Pendlebury, Diane, Roth, Chris, Ryan, Niall J., Sioris, Christopher, Smith, Lesley, and Weigel, Katja

Abstract

The Stratosphere-troposphere Processes and their Role in Climate (SPARC) Data Initiative (SPARC, 2017) performed the first comprehensive assessment of currently available stratospheric composition measurements obtained from an international suite of space-based limb sounders. The initiative's main objectives were (1) to assess the state of data availability, (2) to compile time series of vertically resolved, zonal monthly mean trace gas and aerosol fields, and (3) to perform a detailed intercomparison of these time series, summarizing useful information and highlighting differences among datasets. The datasets extend over the region from the upper troposphere to the lower mesosphere (300–0.1 hPa) and are provided on a common latitude–pressure grid. They cover 26 different atmospheric constituents including the stratospheric trace gases of primary interest, ozone (O3) and water vapor (H2O), major long-lived trace gases (SF6, N2O, HF, CCl3F, CCl2F2, NOy), trace gases with intermediate lifetimes (HCl, CH4, CO, HNO3), and shorter-lived trace gases important to stratospheric chemistry including nitrogen-containing species (NO, NO2, NOx, N2O5, HNO4), halogens (BrO, ClO, ClONO2, HOCl), and other minor species (OH, HO2, CH2O, CH3CN), and aerosol. This overview of the SPARC Data Initiative introduces the updated versions of the SPARC Data Initiative time series for the extended time period 1979–2018 and provides information on the satellite instruments included in the assessment: LIMS, SAGE I/II/III, HALOE, UARS-MLS, POAM II/III, OSIRIS, SMR, MIPAS, GOMOS, SCIAMACHY, ACE-FTS, ACE-MAESTRO, Aura-MLS, HIRDLS, SMILES, and OMPS-LP. It describes the Data Initiative's top-down climatological validation approach to compare stratospheric composition measurements based on zonal monthly mean fields, which provides upper bounds to relative inter-instrument biases and an assessment of how well the instruments are able to capture geophysical features of the stratosphere. An update to previously published evaluations of O3 and H2O monthly mean time series is provided. In addition, example trace gas evaluations of methane (CH4), carbon monoxide (CO), a set of nitrogen species (NO, NO2, and HNO3), the reactive nitrogen family (NOy), and hydroperoxyl (HO2) are presented. The results highlight the quality, strengths and weaknesses, and representativeness of the different datasets. As a summary, the current state of our knowledge of stratospheric composition and variability is provided based on the overall consistency between the datasets. As such, the SPARC Data Initiative datasets and evaluations can serve as an atlas or reference of stratospheric composition and variability during the “golden age” of atmospheric limb sounding. The updated SPARC Data Initiative zonal monthly mean time series for each instrument are publicly available and accessible via the Zenodo data archive (Hegglin et al., 2020).

Published
2021

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