scholarly journals No evidence for tephra in Greenland from the historic eruption of Vesuvius in 79 CE: Implications for geochronology and paleoclimatology

2021 ◽  
Author(s):  
Gill Plunkett ◽  
Michael Sigl ◽  
Hans Schwaiger ◽  
Emma Tomlinson ◽  
Matthew Toohey ◽  
...  
Keyword(s):  
Ice Core ◽  
Trace Element Composition ◽  
Climate Modelling ◽  
Volcanic Event ◽  
Proxy Records ◽  
Aleutian Arc ◽  
Polar Ice Sheets ◽  
Paleoclimate Proxy ◽  
Common Era

Abstract. Volcanic signatures archived in polar ice sheets provide important opportunities to date and correlate ice-core records as well as to investigate the environmental impacts of eruptions. Only the geochemical characterization of volcanic ash (tephra) embedded in the ice strata can confirm the source of the eruption, however, and is a requisite if historical eruption ages are to be used as valid chronological checks on annual ice layer counting. Here we report the investigation of ash particles in a Greenland ice core that are associated with a volcanic sulfuric acid layer previously attributed to the 79 CE eruption of Vesuvius. Major and trace element composition of the particles indicates that the tephra does not derive from Vesuvius but most likely originates from an unidentified eruption in the Aleutian arc. Using ash dispersal modelling, we find that only an eruption large enough to include stratospheric injection is likely to account for the sizeable (24–85 μm) ash particles observed in the Greenland ice at this time. Despite its likely explosivity, this event does not appear to have triggered significant climate perturbations, unlike some other large extra-tropical eruptions. In light of a recent re-evaluation of the Greenland ice-core chronologies, our findings further challenge the previous dating of this volcanic event to 79 CE. We highlight the need for the revised Common Era ice-core chronology to be formally accepted by the wider ice-core and climate modelling communities in order to ensure robust age linkages to precisely dated historical and paleoclimate proxy records.

scholarly journals Quantifying dating uncertainties in layer-counted paleoclimate proxy archives

2021 ◽  
Author(s):  
Eirik Myrvoll-Nilsen ◽  
Keno Riechers ◽  
Martin Wibe Rypdal ◽  
Niklas Boers
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Depth Interval ◽  
Physical Processes ◽  
Noise Component ◽  
Proxy Records ◽  
Complete Uncertainty ◽  
Multivariate Gaussian Process ◽  
Depth Relationship ◽  
Paleoclimate Proxy

Abstract. Paleoclimate proxy records have non-negligible uncertainties that arise from both the proxy measurement and the dating processes. Knowledge of the dating uncertainties is important for a rigorous propagation to further analyses; for example for identification and dating of stadial-interstadial transitions in Greenland ice core records during glacial intervals, for comparing the variability in different proxy archives, and for model-data comparisons in general. In this study we develop a statistical framework to quantify and propagate dating uncertainties in layer-counted proxy archives using the example of the Greenland Ice Core Chronology 2005 (GICC05). We express the number of layers per depth interval as the sum of a structured component that represents both underlying physical processes and biases in layer counting, described by a regression model, and a noise component that represents the fluctuations of the underlying physical processes, as well as unbiased counting errors. The age-depth relationship of the joint dating uncertainties can then be described by a multivariate Gaussian process from which realizations of the chronology can be sampled. We show how the effect of an unknown counting bias can be incorporated in our framework and present refined estimates of the occurrence times of Dansgaard-Oeschger events evidenced in Greenland ice cores together with a complete uncertainty quantification of these timings.

scholarly journals Characterization of Titan Dome, East Antarctica, and potential as an ice core target

2020 ◽  
Author(s):  
Lucas H. Beem ◽  
Duncan A. Young ◽  
Jamin S. Greenbaum ◽  
Donald D. Blankenship ◽  
Jingxue Guo ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Age ◽  
Middle Pleistocene ◽  
South Pole ◽  
Basal Ice ◽  
Core Site ◽  
Age Model ◽  
Middle Pleistocene Transition ◽  
Paleoclimate Proxy

Abstract. Titan Dome is located about 200 km from the South Pole along the 180◦ meridian within the East Antarctic Ice Sheet. Based on sparse data, it is a region that is identified as having a higher probability of containing ice that would capture the middle Pleistocene transition (1.25 to 0.7 Ma) as a paleoclimate proxy. New aerial geophysical observations collected over Titan Dome were used to characterize the region and assess its suitability as a paleoclimate ice core site. The radar coupled with an available ice core age model enabled the tracing of isochronal layers throughout the region which also served as constraints on basal ice age modeling. The results of the survey revealed new basal topographic detail, constrained the location of Titan Dome, which differs between community datasets, and suggests that the basal ice beneath Titan Dome is too young to be relevant to study of the middle Pleistocene transition.

scholarly journals Evaluation of PMIP2 and PMIP3 simulations of mid-Holocene climate in the Indo-Pacific, Australasian and Southern Ocean regions

2016 ◽  
Author(s):  
Duncan Ackerley ◽  
Jessica Reeves ◽  
Cameron Barr ◽  
Helen Bostock ◽  
Kathryn Fitzsimmons ◽  
...  
Keyword(s):  
Southern Ocean ◽  
General Circulation ◽  
Ice Core ◽  
General Circulation Models ◽  
Warm Pool ◽  
Climatic Conditions ◽  
Industrial Control ◽  
Effective Precipitation ◽  
Proxy Records ◽  
Paleoclimate Proxy

Abstract. Paleoclimate proxy reconstruction initiatives, such as the Australian component of the international paleoclimate synthesis effort: INTegration of Ice core, MArine and Terrestrial records (OZ-INTIMATE), are important as they provide evidence of past climatic conditions that are necessary to evaluate global General Circulation Models (GCMs). One of the key outputs from the OZ-INTIMATE project was the production of spatially-coherent, climatic reconstructions over the southern Maritime Continent, Australasia and the Southern Ocean. The OZ-INTIMATE results were presented as regional, "simplified patterns of temperature and effective precipitation" and those regions spanned a large enough area to contain several GCM grid boxes. Therefore, the "upscaling" of individual reconstructions (through OZ-INTIMATE) to a scale that was resolved by GCMs, presented an ideal opportunity for a direct comparison. This study uses the same "simplified patterns of temperature and effective precipitation" approach from OZ-INTIMATE on data from an ensemble of GCMs. The GCM data are taken from the Paleoclimate Modeling Intercomparison Project (PMIP) mid-Holocene (6000 years before present, 6 ka) and pre-industrial control (c1750 C.E., 0 ka) experiments. The synthesis presented here shows that, on the whole, the models and proxies agree on the differences in climate state for 6 ka relative to 0 ka, when they are insolation driven. The main disagreement between the models and proxies occurs over the Tropical West Pacific warm pool and arises from an intensification of an existing error (the "cold tongue bias"). This study also presents a mechanism whereby the strength of the Southern Hemisphere, mid-latitude westerly wind strength reduces but rainfall increases over the southern temperate zone of Australia. Such a mechanism may be useful for resolving disparities between different regional proxy records, and model simulations. Finally, after assessing the available datasets (model and proxy), opportunities for better model-proxy integrated research are presented.

scholarly journals Orbital forcings of the Earth’s climate in wavelet domain

2005 ◽  
Vol 1 (2) ◽  
pp. 193-214 ◽  
Author(s):  
A. V. Glushkov ◽  
V. N. Khokhlov ◽  
N. S. Loboda ◽  
V. D. Rusov ◽  
V. N. Vaschenko
Keyword(s):  
Wavelet Transform ◽  
Ice Core ◽  
Wavelet Domain ◽  
Local Maxima ◽  
Orbital Parameters ◽  
Proxy Records ◽  
Earth’S Climate ◽  
Almost All ◽  
Paleoclimate Proxy ◽  
The Antarctic

Abstract. We examine two paleoclimate proxy records – the temperature differences from the Antarctic Vostok ice core and the composite δ18O record from three sites (V19-30, ODP 677, and ODP 846) – in order to search for indications of orbital forcings. We demonstrate that the non-decimated wavelet transform is an appropriate tool for investigating temporarily changing spectral properties of records. Our results indicate that abrupt climate warmings with cyclicity of ~100 kiloyears during the last 400 kiloyears were caused by the combined unidirectional influences of three orbital parameters and the eccentricity can be considered as a modulator defining transitions from the Ice Ages to the periods of comparative warmings. Non-decimated wavelet transform avails discovering the possible part played in climate change by the eccentricity-forced variations. Up to approximately 1.7 million years BP, the influence of this variations of eccentricity appears in increasing for almost all local maxima of δ18O. Since the ~1.7 million years BP, minor and significant maxima alternated and this not affected as much the variations of δ18O.

Ice-Core Pollen Record of Climatic Changes in the Central Andes during the last 400 yr

2005 ◽  
Vol 64 (2) ◽  
pp. 272-278 ◽  
Author(s):  
Kam-biu Liu ◽  
Carl A. Reese ◽  
Lonnie G. Thompson
Keyword(s):  
Little Ice Age ◽  
Ice Core ◽  
Climatic Changes ◽  
Ice Age ◽  
Striking Similarity ◽  
Pollen Record ◽  
Dry Period ◽  
Proxy Records ◽  
Ice Cap ◽  
Ice Accumulation

AbstractThis paper presents a high-resolution ice-core pollen record from the Sajama Ice Cap, Bolivia, that spans the last 400 yr. The pollen record corroborates the oxygen isotopic and ice accumulation records from the Quelccaya Ice Cap and supports the scenario that the Little Ice Age (LIA) consisted of two distinct phases�"a wet period from AD 1500 to 1700, and a dry period from AD 1700 to 1880. During the dry period xerophytic shrubs expanded to replace puna grasses on the Altiplano, as suggested by a dramatic drop in the Poaceae/Asteraceae (P/A) pollen ratio. The environment around Sajama was probably similar to the desert-like shrublands of the Southern Bolivian Highlands and western Andean slopes today. The striking similarity between the Sajama and Quelccaya proxy records suggests that climatic changes during the Little Ice Age occurred synchronously across the Altiplano.

The Toba Volcanic Event and Interstadial/Stadial Climates at the Marine Isotopic Stage 5 to 4 Transition in the Northern Indian Ocean

2002 ◽  
Vol 57 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Hartmut Schulz ◽  
Kay-Christian Emeis ◽  
Helmut Erlenkeuser ◽  
Ulrich von Rad ◽  
Christian Rolf
Keyword(s):  
Arabian Sea ◽  
Water Productivity ◽  
Ice Core ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Sediment Supply ◽  
Volcanic Event ◽  
Additional Support ◽  
Marine Isotope Stage 5 ◽  
A Minor

AbstractThe Toba volcanic event, one of the largest eruptions during the Quaternary, is documented in marine sediment cores from the northeastern Arabian Sea. On the crest of the Murray Ridge and along the western Indian continental margin, we detected distinct concentration spikes and ash layers of rhyolithic volcanic shards near the marine isotope stage 5–4 boundary with the chemical composition of the “Youngest Toba Tuff.” Time series of the Uk′37-alkenone index, planktic foraminiferal species, magnetic susceptibility, and sediment accumulation rates from this interval show that the Toba event occurred between two warm periods lasting a few millennia. Using Toba as an instantaneous stratigraphic marker for correlation between the marine- and ice-core chronostratigraphies, these two Arabian Sea climatic events correspond to Greenland interstadials 20 and 19, respectively. Our data sets thus depict substantial interstadial/stadial fluctuations in sea-surface temperature and surface-water productivity. We show that variable terrigenous (eolian) sediment supply played a crucial role in transferring and preserving the productivity signal in the sediment record. Within the provided stratigraphic resolution of several decades to centennials, none of these proxies shows a particular impact of the Toba eruption. However, our results are additional support that Toba, despite its exceptional magnitude, had only a minor impact on the evolution of low-latitude monsoonal climate on centennial to millennial time scales.

scholarly journals Simulated features of the air-hydrate formation process in the Antarctic ice sheet at Vostok

1999 ◽  
Vol 29 ◽  
pp. 191-201 ◽  
Author(s):  
Andrey N. Salamatin ◽  
Vladimir Ya. Lipenkov ◽  
Takeo Hondoh ◽  
Tomoko Ikeda
Keyword(s):  
Ice Core ◽  
Hydrate Formation ◽  
Ice Cores ◽  
Air Bubbles ◽  
Air Bubble ◽  
Self Diffusion ◽  
Rate Limiting Step ◽  
Typical Time ◽  
Polar Ice Sheets ◽  
Selective Diffusion

AbstractA recently developed theory of post-nucleation conversion of an air bubble to air-hydrate crystal in ice is applied to simulate two different types of air-hydrate formation in polar ice sheets. The work is focused on interpretation of the Vostok (Antarctica) ice-core data. The hydrostatic compression of bubbles is the rate-limiting step of the phase transformation which is additionally influenced by selective diffusion of the gas components from neighboring air bubbles. The latter process leads to the gas fractionation resulting in lower (higher) N2/O2 ratios in air hydrates (coexisting bubbles) with respect to atmospheric air. The typical time of the post-nucleation conversion decreases at Vostok from 1300-200 a at the beginning to 50-3 a at the end of the transition zone. The model of the diffusive transport of the air constituents from air bubbles to hydrate crystals is constrained by the data of Raman spectra measurements. The oxygen and nitrogen self-diffusion (permeation) coefficients in ice are determined at 220 K as 4.5 × 10−8 and 9.5 × 10−8 mm2 a−1, respectively while the activation energy is estimated to be about 50 kJ mol−1. The gas-fractionation time-scale at Vostok, τF ∼300 a, appears to be two orders of magnitude less than the typical time of the air-hydrate nucleation, τz ∼30-35 ka, and thus the condition for the extreme gas fractionation, τF ≪ τz is satisfied. Application of the theory to the GRIP and GISP2 ice cores shows that on average, a significant gas fractionation cannot be expected for air hydrates in central Greenland. However, a noticeable (statistically valid) nitrogen enrichment might be observed in the last air bubbles at the end of the transition.

scholarly journals The Iso2k Database: A global compilation of paleo-δ<sup>18</sup>O and δ<sup>2</sup>H records to aid understanding of Common Era climate

2020 ◽  
Author(s):  
Bronwen L. Konecky ◽  
Nicholas P. McKay ◽  
Olga V. Churakova (Sidorova) ◽  
Laia Comas-Bru ◽  
Emilie P. Dassié ◽  
...  
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Global Environmental Change ◽  
Global Scale ◽  
Proxy Records ◽  
Global Environmental ◽  
Past 2000 Years ◽  
Wide Range ◽  
Terrestrial Sediments ◽  
Common Era

Abstract. Reconstructions of global hydroclimate during the Common Era (CE; the past ~ 2000 years) are important for providing context for current and future global environmental change. Stable isotope ratios in water are quantitative indicators of hydroclimate on regional to global scales, and these signals are encoded in a wide range of natural geologic archives. Here we present the Iso2k database, a global compilation of previously published datasets from a variety of natural archives that record the stable oxygen (δ18O) or hydrogen (δ2H) isotopic composition of environmental waters, which reflect hydroclimate changes over the CE. The Iso2k database contains 756 isotope records from the terrestrial and marine realms, including: glacier and ground ice (205); speleothems (68); corals, sclerosponges, and mollusks (145); wood (81); lake sediments and other terrestrial sediments (e.g., loess) (158); and marine sediments (99). Individual datasets have temporal resolutions ranging from sub-annual to centennial, and include chronological data where available. A fundamental feature of the database is its comprehensive metadata, which will assist both experts and non-experts in the interpretation of each record and in data synthesis. Key metadata fields have standardized vocabularies to facilitate comparisons across diverse archives and with climate model simulated fields. This is the first global-scale collection of water isotope proxy records from multiple types of geological and biological archives. It is suitable for evaluating hydroclimate processes through time and space using large-scale synthesis, model-data intercomparison and (paleo)data assimilation. The Iso2k database is available for download at: https://doi.org/10.6084/m9.figshare.11553162 (McKay and Konecky, 2020).

The Young Island Ice Core - Climate Information of a Melty Archive

2021 ◽  
Author(s):  
Dorothea Elisabeth Moser ◽  
Elizabeth R. Thomas ◽  
Sarah Jackson ◽  
Joel B. Pedro ◽  
Bradley Markle
Keyword(s):  
Ross Sea ◽  
Ice Core ◽  
Reanalysis Data ◽  
Climate Data ◽  
Antarctic Region ◽  
Paleoclimate Reconstruction ◽  
Future Studies ◽  
Proxy Records ◽  
Surface Melt ◽  
Instrumental Period

&lt;p&gt;Climate data from the sub-Antarctic region are extremely sparse, with few records available beyond the instrumental period. Here, we investigate the suitability of the first-ever ice core collected from Young Island, in the NW Ross Sea, to capture changes in climate. Despite the presence of surface melt at this maritime location, our findings indicate that stable water isotope and trace element records can still hold potential for paleoclimate reconstruction. We apply two multi-proxy dating approaches based on winter and summer signatures, develop an ice core chronology, and contextualize our findings using a local automatic weather station and reanalysis data. Subsequently, we draw first conclusions about the surface conditions at Young Island and discuss the site&amp;#8217;s potential for future studies aimed at paleoclimate reconstruction and resolving the effects of surface melt on proxy records.&lt;/p&gt;

scholarly journals Modelling the Antarctic Ice Sheet across the mid-Pleistocene transition – implications for Oldest Ice

2019 ◽  
Vol 13 (7) ◽  
pp. 2023-2041 ◽  
Author(s):  
Johannes Sutter ◽  
Hubertus Fischer ◽  
Klaus Grosfeld ◽  
Nanna B. Karlsson ◽  
Thomas Kleiner ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Sheet ◽  
Middle Pleistocene ◽  
Climate Modelling ◽  
Geothermal Heat ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Climate Conditions ◽  
West Antarctic ◽  
Pleistocene Climate

Abstract. The international endeavour to retrieve a continuous ice core, which spans the middle Pleistocene climate transition ca. 1.2–0.9 Myr ago, encompasses a multitude of field and model-based pre-site surveys. We expand on the current efforts to locate a suitable drilling site for the oldest Antarctic ice core by means of 3-D continental ice-sheet modelling. To this end, we present an ensemble of ice-sheet simulations spanning the last 2 Myr, employing transient boundary conditions derived from climate modelling and climate proxy records. We discuss the imprint of changing climate conditions, sea level and geothermal heat flux on the ice thickness, and basal conditions around previously identified sites with continuous records of old ice. Our modelling results show a range of configurational ice-sheet changes across the middle Pleistocene transition, suggesting a potential shift of the West Antarctic Ice Sheet to a marine-based configuration. Despite the middle Pleistocene climate reorganisation and associated ice-dynamic changes, we identify several regions conducive to conditions maintaining 1.5 Myr (million years) old ice, particularly around Dome Fuji, Dome C and Ridge B, which is in agreement with previous studies. This finding strengthens the notion that continuous records with such old ice do exist in previously identified regions, while we are also providing a dynamic continental ice-sheet context.

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