Unknown Eruption Source Parameters Cause Large Uncertainty in Historical Volcanic Radiative Forcing Reconstructions

Marshall, Lauren; Schmidt, Anja; Johnson, Jill S.; Mann, Graham; Lee, Lindsay; Rigby, Richard; Carslaw, K. S.

doi:10.1029/2020jd033578

Cited by 14 publications

(8 citation statements)

References 113 publications

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“…Although reconstructions of past volcanic forcing have improved (Toohey and Sigl 2017), there is uncertainty in the conversion between volcanic sulfate deposition and the stratospheric sulfur burden, with modelling studies demonstrating that this depends on the properties of an eruption (Marshall et al 2021;Toohey et al 2013) and the model itself (Marshall et al 2018). Uncertainties in past volcanic forcing underpin many model-data discrepancies (e.g.…”

Section: Reconstructing Past Volcanic Forcingmentioning

confidence: 99%

Volcanic effects on climate: recent advances and future avenues

et al. 2022

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Volcanic eruptions have long been studied for their wide range of climatic effects. Although global-scale climatic impacts following the formation of stratospheric sulfate aerosol are well understood, many aspects of the evolution of the early volcanic aerosol cloud and regional impacts are uncertain. In the last twenty years, several advances have been made, mainly due to improved satellite measurements and observations enabling the effects of small-magnitude eruptions to be quantified, new proxy reconstructions used to investigate the impact of past eruptions, and state-of-the-art aerosol-climate modelling that has led to new insights on how volcanic eruptions affect the climate. Looking to the future, knowledge gaps include the role of co-emissions in volcanic plumes, the impact of eruptions on tropical hydroclimate and Northern Hemisphere winter climate, and the role of eruptions in long-term climate change. Future model development, dedicated model intercomparison projects, interdisciplinary collaborations, and the application of advanced statistical techniques will facilitate more complex and detailed studies. Ensuring that the next large-magnitude explosive eruption is well observed will be critical in providing invaluable observations that will bridge remaining gaps in our understanding.

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Section: Reconstructing Past Volcanic Forcingmentioning

confidence: 99%

Volcanic effects on climate: recent advances and future avenues

et al. 2022

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“…Importantly, our simulations can provide insights about and estimates of the uncertainties associated with L G which originate from both atmospheric variability and unknown eruption source parameters. Our estimates build upon previous assessments of uncertainties [47,48], aiming to offer additional insight as well as improve our understanding of intermodel disagreements.…”

Section: Modelled Sulphate Deposition and Implications For Volcanic F...mentioning

confidence: 80%

“…To obtain a reliable estimate of the random error of L G resulting from unknown eruption source parameters, it is necessary to sample a wide distribution of eruption source parameters that are representative of real volcanic eruptions. Recent studies applying statistical emulation [48,58] have demonstrated the potential of alternative approaches for evaluating how eruption source parameters impact both radiative forcing and sulphate deposition.…”

Section: Limitations and Future Workmentioning

confidence: 99%

Revisiting the volcanic forcing of high-latitude Northern Hemisphere eruptions

Fuglestvedt

Zhuo

Toohey

et al. 2023

Preprint

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High-latitude explosive volcanic eruptions can cause substantial cooling on a hemispheric scale. However, our current understanding of these events remains limited. In this study, we employ a whole atmosphere chemistry-climate model with prognostic stratospheric aerosols to simulate Northern Hemisphere (NH) high-latitude explosive volcanic eruptions of similar magnitude to the 1991 eruption of Mt. Pinatubo. Our simulations reveal that the lifetime of sulphur dioxide and the growth of volcanic sulphate aerosols are strongly influenced by the initial state of the NH polar vortex. The stability of the polar vortex during the first weeks after an eruption determines the latitudinal dispersion of the injected gases within the stratosphere. Consequently, interannual variability of the polar vortex stability introduces a variability in the modelled cumulative radiative forcing of more than 20 %. We also test the aerosol evolution’s sensitivity to co-injection of sulphur and halogens, injection season, and injection altitude, and show how processes related to aerosol formation, lifetime, and growth impact the resulting radiative forcing. Notably, several of the sensitivities are of similar magnitude to the variability stemming from initial conditions, highlighting the significant influence of atmospheric variability. Finally, we compare the modelled volcanic sulphate deposition over the Greenland ice sheet with the relationship assumed in reconstructions of past NH extratropical eruptions. Our analysis yields an estimated Greenland transfer function for NH extratropical eruptions of 0.44 × 10⁹ km² . If applied to ice core data, this value would produce volcanic stratospheric sulphur injections from NH extratopical eruptions 23 % smaller than in currently used volcanic forcing reconstructions. Furthermore, the uncertainty attached to the Greenland transfer function for NH extratropical eruptions, which propagates into the estimate of volcanic stratospheric sulphur injection, needs to be at least doubled to account for both atmospheric variability and unknown eruption source parameters. Our results offer insights into the complex dynamics shaping the impacts of both historical and future NH high-latitude eruptions. Furthermore, they underscore the need for more accurate representation of these events in existing volcanic forcing reconstructions, with the aim of improving our understanding of their climatic impacts.

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“…Sulfate concentrations in ice cores have been used to estimate stratospheric sulfur loading, relying on the transport and deposition of volcanic sulfate aerosols to ice sheets 1–2 years post‐eruption (Toohey & Sigl, 2017). While this strategy is useful for identifying the timing of large eruptions and their relative magnitudes, it does not provide source constraints nor does it distinguish stratospheric fall‐out versus sulfur transported through the troposphere (Marshall et al., 2021). In Figure 3b, we compare petrological estimates of sulfur load and ice core estimates over the past 2,500 years, and find that petrologic estimates are systematically higher than the modeled ice core deposition.…”

Section: Multi‐methods Assessment Of Stratospheric S Injectionmentioning

confidence: 99%

A New Multi‐Method Assessment of Stratospheric Sulfur Load From the Okmok II Caldera‐Forming Eruption of 43 BCE

Peccia,

Moussallam,

Plank

et al. 2023

Geophysical Research Letters

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The 43 BCE eruption of Okmok Volcano has been proposed to have had a significant climate cooling impact in the Northern Hemisphere. In this study, we quantify the climate cooling potential of the Okmok II eruption by measuring sulfur concentration in melt inclusions (up to 1,606 ppm) and matrix glasses and estimate a total of 62 ± 16 Tg S released. The proportion reaching the stratosphere (2.5%–25%, i.e., 1.5–15.5 Tg S) was constrained by physical modeling of the caldera‐collapse eruption. Using the NASA Goddard Institute for Space Studies E2.2 climate model we found a linear response between cooling and stratospheric sulfur load (0.05–0.08°C/Tg S). Thus, the 1–2°C of cooling derived from proxy records would require 16–32 Tg sulfur injection. This study underscores the importance of combining approaches to estimate stratospheric S load. For Okmok II, we find all methods are consistent with a range of 15–16 Tg S.

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Unknown Eruption Source Parameters Cause Large Uncertainty in Historical Volcanic Radiative Forcing Reconstructions

Cited by 14 publications

References 113 publications

Volcanic effects on climate: recent advances and future avenues

Volcanic effects on climate: recent advances and future avenues

Revisiting the volcanic forcing of high-latitude Northern Hemisphere eruptions

A New Multi‐Method Assessment of Stratospheric Sulfur Load From the Okmok II Caldera‐Forming Eruption of 43 BCE

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