The injection of sulfur into the stratosphere by explosive volcanic eruptions is the cause of significant climate variability. Based on sulfate records from a suite of ice cores from Greenland and ...Antarctica, the eVolv2k database includes estimates of the magnitudes and approximate source latitudes of major volcanic stratospheric sulfur injection (VSSI) events from 500 BCE to 1900 CE, constituting an update of prior reconstructions and an extension of the record by 1000 years. The database incorporates improvements to the ice core records (in terms of synchronisation and dating) and refinements to the methods used to estimate VSSI from ice core records, and it includes first estimates of the random uncertainties in VSSI values. VSSI estimates for many of the largest eruptions, including Samalas (1257), Tambora (1815), and Laki (1783), are within 10 % of prior estimates. A number of strong events are included in eVolv2k which are largely underestimated or not included in earlier VSSI reconstructions, including events in 540, 574, 682, and 1108 CE. The long-term annual mean VSSI from major volcanic eruptions is estimated to be ∼ 0.5 Tg S yr−1, ∼ 50 % greater than a prior reconstruction due to the identification of more events and an increase in the magnitude of many intermediate events. A long-term latitudinally and monthly resolved stratospheric aerosol optical depth (SAOD) time series is reconstructed from the eVolv2k VSSI estimates, and the resulting global mean SAOD is found to be similar (within 33 %) to a prior reconstruction for most of the largest eruptions. The long-term (500 BCE–1900 CE) average global mean SAOD estimated from the eVolv2k VSSI estimates including a constant background injection of stratospheric sulfur is ∼ 0.014, 30 % greater than a prior reconstruction. These new long-term reconstructions of past VSSI and SAOD variability give context to recent volcanic forcing, suggesting that the 20th century was a period of somewhat weaker than average volcanic forcing, with current best estimates of 20th century mean VSSI and SAOD values being 25 and 14 % less, respectively, than the mean of the 500 BCE to 1900 CE period. The reconstructed VSSI and SAOD data are available at https://doi.org/10.1594/WDCC/eVolv2k_v2.
Patients with haemophilia (PwH) suffer from chronic pain due to joint alterations induced by recurring haemorrhage.
This study aimed to investigate the relationship between structural alterations and ...pain perception at the ankle joint in PwH.
Ankle joints of 79 PwH and 57 healthy controls (Con) underwent ultrasound examination (US) and assessment of pain sensitivity via pressure pain thresholds (PPT). US discriminated between joint activity (synovitis) and joint damage (cartilage and/or bone degeneration) applying the HEAD-US protocol. Based on US-findings, five subgroups were built: PwH with activity/damage, PwH with activity/no damage, PwH with no activity/no damage, controls with activity/no damage and controls with no activity/no damage.
Joint activity and joint damage were significantly increased in ankles of PwH compared to Con (p ≤.001). Subgroup analysis revealed that structural alterations negatively impact pain perception. This is particularly evident when comparing PwH with both activity/damage to PwH with no activity/no damage at the tibiotalar joint (p = .001). At the fibulotalar joint, no significant differences were observed between PwH subgroups. Further analysis showed that both joint activity and joint damage result in an increase in pain sensitivity (p ≤.001).
The data suggest a relation between joint activity, joint damage and pain perception in PwH. Even minor changes due to synovitis appear to affect pain perception, with the effect not intensifying at higher levels of inflammation. In terms of joint damage, severe degeneration leads to a sensitised pain state most robustly, whereas initial changes do not seem to significantly affect pain perception.
•High resolution S isotopes measured over volcanic events in ice cores by MC-ICP-MS.•S isotopes in ice fingerprint stratospheric tropical and extra-tropical eruptions.•Isotope mass balance constrains ...proportion of stratospheric sulfate deposited in ice.•Method can be used to improve reconstructions of volcanic forcing of climate.
The record of volcanic forcing of climate over the past 2500 years is based primarily on sulfate concentrations in ice cores. Of particular interest are large volcanic eruptions with plumes that reached high altitudes in the stratosphere, as these afford sulfate aerosols the longest residence time in the atmosphere, and thus have the greatest impact on radiative forcing. Sulfur isotopes measured in ice cores can be used to identify these large eruptions because stratospheric sulfur is exposed to UV radiation, which imparts a time-evolving mass independent fractionation (MIF) that is preserved in the ice. However, sample size requirements of traditional measurement techniques mean that the MIF signal may be obscured, leading to an inconclusive result. Here we present a new method of measuring sulfur isotopes in ice cores by multi-collector inductively coupled plasma mass spectrometry, which reduces sample size requirements by three orders of magnitude. Our method allows us to measure samples containing as little as 10 nmol of sulfur, with a precision of 0.11‰ for δ34S and 0.10‰ for Δ33S, enabling a high-temporal resolution over ice core sulfate peaks. We tested this method on known tropical (Tambora 1815 and Samalas 1257) and extra-tropical (Katmai/Novarupta 1912) stratospheric eruptions from the Tunu2013 ice core in Greenland and the B40 ice core from Antarctica. These high-resolution sulfur isotope records suggest a distinct difference between the signatures of tropical versus extra-tropical eruptions. Furthermore, isotope mass balance on sulfate from extra-tropical eruptions provides a means to estimate the fraction of sulfate deposited that was derived from the stratosphere. This technique applied to unidentified eruptions in ice cores may thus improve the record of explosive volcanism and its forcing of climate.
The origin of two large peaks in the atmospheric radiocarbon ((14)C) concentration at AD 774/5 and 993/4 is still debated. There is consensus, however, that these features can only be explained by an ...increase in the atmospheric (14)C production rate due to an extraterrestrial event. Here we provide evidence that these peaks were most likely produced by extreme solar events, based on several new annually resolved (10)Be measurements from both Arctic and Antarctic ice cores. Using ice core (36)Cl data in pair with (10)Be, we further show that these solar events were characterized by a very hard energy spectrum with high fluxes of solar protons with energy above 100 MeV. These results imply that the larger of the two events (AD 774/5) was at least five times stronger than any instrumentally recorded solar event. Our findings highlight the importance of studying the possibility of severe solar energetic particle events.
Volcanic eruptions provide tests of human and natural system sensitivity to abrupt shocks because their repeated occurrence allows the identification of systematic relationships in the presence of ...random variability. Here we show a suppression of Nile summer flooding via the radiative and dynamical impacts of explosive volcanism on the African monsoon, using climate model output, ice-core-based volcanic forcing data, Nilometer measurements, and ancient Egyptian writings. We then examine the response of Ptolemaic Egypt (305-30 BCE), one of the best-documented ancient superpowers, to volcanically induced Nile suppression. Eruptions are associated with revolt onset against elite rule, and the cessation of Ptolemaic state warfare with their great rival, the Seleukid Empire. Eruptions are also followed by socioeconomic stress with increased hereditary land sales, and the issuance of priestly decrees to reinforce elite authority. Ptolemaic vulnerability to volcanic eruptions offers a caution for all monsoon-dependent agricultural regions, presently including 70% of world population.The degree to which human societies have responded to past climatic changes remains unclear. Here, using a novel combination of approaches, the authors show how volcanically-induced suppression of Nile summer flooding led to societal unrest in Ptolemaic Egypt (305-30 BCE).
The injection of sulfur into the stratosphere by volcanic eruptions is the dominant driver of natural climate variability on interannual to multidecadal timescales. Based on a set of continuous ...sulfate and sulfur records from a suite of ice cores from Greenland and Antarctica, the HolVol v.1.0 database includes estimates of the magnitudes and approximate source latitudes of major volcanic stratospheric sulfur injection (VSSI) events for the Holocene (from 9500 BCE or 11 500 years BP to 1900 CE), constituting an extension of the previous record by 7000 years. The database incorporates new-generation ice-core aerosol records with a sub-annual temporal resolution and a demonstrated sub-decadal dating accuracy and precision. By tightly aligning and stacking the ice-core records on the WD2014 chronology from Antarctica, we resolve long-standing inconsistencies in the dating of ancient volcanic eruptions that arise from biased (i.e., dated too old) ice-core chronologies over the Holocene for Greenland. We reconstruct a total of 850 volcanic eruptions with injections in excess of 1 teragram of sulfur (Tg S); of these eruptions, 329 (39 %) are located in the low latitudes with bipolar sulfate deposition, 426 (50 %) are located in the Northern Hemisphere extratropics (NHET) and 88 (10 %) are located in the Southern Hemisphere extratropics (SHET). The spatial distribution of the reconstructed eruption locations is in agreement with prior reconstructions for the past 2500 years. In total, these eruptions injected 7410 Tg S into the stratosphere: 70 % from tropical eruptions and 25 % from NH extratropical eruptions. A long-term latitudinally and monthly resolved stratospheric aerosol optical depth (SAOD) time series is reconstructed from the HolVol VSSI estimates, representing the first Holocene-scale reconstruction constrained by Greenland and Antarctica ice cores. These new long-term reconstructions of past VSSI and SAOD variability confirm evidence from regional volcanic eruption chronologies (e.g., from Iceland) in showing that the Early Holocene (9500–7000 BCE) experienced a higher number of volcanic eruptions (+16 %) and cumulative VSSI (+86 %) compared with the past 2500 years. This increase coincides with the rapid retreat of ice sheets during deglaciation, providing context for potential future increases in volcanic activity in regions under projected glacier melting in the 21st century. The reconstructed VSSI and SAOD data are available at https://doi.org/10.1594/PANGAEA.928646 (Sigl et al., 2021).
The mid-latitude westerly winds of the Southern Hemisphere play a central role in the global climate system via Southern Ocean upwelling.sup.1, carbon exchange with the deep ocean.sup.2, Agulhas ...leakage (transport of Indian Ocean waters into the Atlantic).sup.3 and possibly Antarctic ice-sheet stability.sup.4. Meridional shifts of the Southern Hemisphere westerly winds have been hypothesized to occur.sup.5,6 in parallel with the well-documented shifts of the intertropical convergence zone.sup.7 in response to Dansgaard-Oeschger (DO) events-- abrupt North Atlantic climate change events of the last ice age. Shifting moisture pathways to West Antarctica.sup.8 are consistent with this view but may represent a Pacific teleconnection pattern forced from the tropics.sup.9. The full response of the Southern Hemisphere atmospheric circulation to the DO cycle and its impact on Antarctic temperature remain unclear.sup.10. Here we use five ice cores synchronized via volcanic markers to show that the Antarctic temperature response to the DO cycle can be understood as the superposition of two modes: a spatially homogeneous oceanic 'bipolar seesaw' mode that lags behind Northern Hemisphere climate by about 200 years, and a spatially heterogeneous atmospheric mode that is synchronous with abrupt events in the Northern Hemisphere. Temperature anomalies of the atmospheric mode are similar to those associated with present-day Southern Annular Mode variability, rather than the Pacific-South American pattern. Moreover, deuterium-excess records suggest a zonally coherent migration of the Southern Hemisphere westerly winds over all ocean basins in phase with Northern Hemisphere climate. Our work provides a simple conceptual framework for understanding circum-Antarctic temperature variations forced by abrupt Northern Hemisphere climate change. We provide observational evidence of abrupt shifts in the Southern Hemisphere westerly winds, which have previously documented.sup.1-3 ramifications for global ocean circulation and atmospheric carbon dioxide. These coupled changes highlight the necessity of a global, rather than a purely North Atlantic, perspective on the DO cycle.
Small‐to‐moderate volcanic eruptions can lead to significant surface cooling when they occur clustered, as observed in recent decades. In this study, based on new high‐resolution ice‐core data from ...Greenland, we produce a new volcanic forcing data set that includes several small‐to‐moderate eruptions not included in prior reconstructions and investigate their climate impacts of the early 19th century through ensemble simulations with the Max Planck Institute Earth System Model. We find that clustered small‐to‐moderate eruptions produce significant additional global surface cooling (∼0.07 K) during the period 1812–1820, superposing with the cooling by large eruptions in 1809 (unidentified location) and 1815 (Tambora). This additional cooling helps explain the reconstructed long‐lasting cooling after the large eruptions, but simulated regional impacts cannot be confirmed with reconstructions due to a low signal‐to‐noise ratio. This study highlights the importance of small‐to‐moderate eruptions for climate simulations as their impacts can be comparable with that of solar irradiance changes.
Plain Language Summary
Volcanic eruptions can influence global climate through the emission of sulfuric acids shielding Earth from incoming solar radiation. Previous volcanic reconstructions based on ice‐cores from the polar regions, however, only considered very strong volcanic eruptions. In this study, based on new ice‐core measurements from Greenland, we reconstruct for the first time volcanic sulfur emissions from small to medium‐sized eruptions and investigate their impact on climate in the early 19th century through experiments with the Max Planck Institute Earth System Model (MPI‐ESM1.2‐LR). We find that clustering of small to medium‐sized eruptions can cause significant global surface cooling (∼0.07 K), which during the 1812–1820 period amplified the cooling caused by the two known large eruptions of the period (1809 unidentified and 1815 Tambora). This additional surface cooling from small eruptions helps explain the long‐lasting cooling after the two strong eruptions generally found in the reconstruction, but the simulated regional impacts cannot be fully confirmed with reconstructions that are too noisy. This study highlights the importance of including small‐to‐moderate eruptions for climate model simulations as their impacts are comparable with that of solar irradiance forcing.
Key Points
A new ice‐core based reconstruction of volcanic sulfate in the atmosphere (1733–1895) includes small‐to‐moderate eruptions
Small‐to‐moderate eruptions can induce significant surface cooling and help explain the long‐lasting cooling in the early 19th century
Regional cooling from small‐to‐moderate eruptions may be influenced by the circulation changes from the 1815 Tambora for over 10 years
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