Quantifying the influence of natural forcing on oxygen isotope variability in alpine and polar ice core sites

2020 ◽  
Author(s):  
Kira Rehfeld ◽  
Moritz Kirschner ◽  
Max Holloway ◽  
Louise Sime
Keyword(s):  
Surface Temperature ◽  
Oxygen Isotope ◽  
Ice Core ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Isotope Ratios ◽  
Tibet Plateau ◽  
European Alps ◽  
Last Millennium ◽  
The Tibet Plateau

<p>Stable water isotope ratios are routinely used to infer past climatic conditions in palaeoclimate archives. In particular, oxygen isotope ratios in precipitation co-vary with temperature in high latitudes, and have been established as indicators for past temperature changes in ice-cores. The timescales for which this holds, and the validity of spatial/temporal regression slopes are difficult to constrain based on the observational record.</p><p>Here, surface climate and oxygen isotope ratio variability are compared across an ensemble of millennial-long simulations with the isotope-enabled version of the Hadley Centre Coupled Model version 3 (iHadCM3). The ensemble consists, amongst others, of paired experiments. One half were performed as conventional palaeoclimate equilibrium simulations for the Last Glacial Maximum (LGM, orbital and trace gas concentrations of 21kyrs BP), the mid Holocene (conditions 6kyrs BP) and the pre-industrial period (PI, 1850CE) analogously to the simulations in the Palaeoclimate Modeling Intercomparison Project. The second half of the ensemble is additionally perturbed by radiative forcing variations from solar variability and volcanic forcing as for the last millennium. Each simulation is continued for at least 1050 years.</p><p>We find that global mean surface temperature and precipitation decrease significantly in all considered climate states (LGM, 6k, PI). Post-volcanic temperature reduction is fairly consistent across the globe, but weak in Antarctica. In the PI state, we find a significant increase in the AMOC strength after eruptions. This does not occur for the LGM state. No significant responses to solar forcing were detectable in the isotopic record. Correlating precipitation-weighted δ<sup>18</sup>O (δ<sup>18</sup>O<sub>pr</sub>) at these locations with surface temperature across the globe shows strong linear relationships and teleconnections. In Greenland, δ<sup>18</sup>O<sub>pr</sub>, at the decadal scale, shows high correlations across the Northern hemisphere for the PI simulations, but this spatial representativeness is smaller in the LGM.</p><p>We finally examine the detectability of strong interannual volcanic impacts in the climate and isotope record at ice core drill sites in West and East Antarctica, Greenland, the European Alps and the Tibet Plateau. At all locations, modeled isotope and climate variance is higher in the naturally forced simulations. On annual time scales, we find only weak imprints of sub-supervolcanic eruptions in annual δ<sup>18</sup>O<sub>pr</sub> at most locations compared to interannual variability, with the exception of the Tibet plateau. We extend this epoch analysis to high-resolution ice core records to assess the consistency between modeled and measured isotope variations for prominent volcanic eruptions over the last millennium.</p><p>The inclusion of natural forcing in the simulations alleviates the discrepancy between modeled and observed isotope variability. However, the gap cannot be closed completely. This suggests that improving our understanding of the signal formation process, the dynamical origins of isotope signatures, and model biases at all latitudes is important to constrain the regional to global representativeness of stable water isotopes in ice cores.</p>

Comparison of isotopic signatures in ice core and speleothem records to an isotope enabled climate model simulation for the last millennium

2021 ◽  
Author(s):  
Yannick Heiser ◽  
Janica Bühler ◽  
Mathieu Casado ◽  
Kira Rehfeld
Keyword(s):  
Climate Variability ◽  
Climate Model ◽  
Southern Oscillation ◽  
Ice Core ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Last Millennium ◽  
Polar Ice ◽  
Geophysical Research ◽  
Ice Core Records

<div> <div> <div> <p>Stable water isotope ratios (δ18O) measured in e.g. ice-cores or speleothems have long been established as temperature proxies and are used to reconstruct past climate variability but still require more quantification on spatial and temporal scales. The high resolution ice-core archives are mainly found in polar and alpine regions, whereas the speleothem records mostly grow in caves in low to mid-latitudes. To bridge between the archives, models are needed to compare the climate variability stored in both ice-cores and speleothems, which will help to evaluate future projections of climate variability.</p> <p>Here, we compare a transient isotope enabled simulation from the Hadley Center Climate Model version 3 (iHadCM3) [1, 2] to polar ice-core records from the iso2k database [3] for the last millennium (LM, 850-1850 CE). We analyze time-averaged isotope ratios and their variability on decadal to centennial timescales to systematically evaluate the offsets and correlation patterns between simulated and recorded isotopes to specific climatic drivers. For better comparability between speleothem and ice core-archives, we also include non-polar ice core records, as well as monitored precipitation δ18O from a global database.</p> <p>We find the time-averaged δ18O offsets between the simulation and ice-core records to be fairly small for most of the polar ice-core sites, indicating a low simulation climate offset.<br>As expected, we find the simulated δ18O variability to be higher in the polar regions of ice-core locations, compared to the simulated variability at speleothem cave locations. Recorded δ18O variability is also generally higher as stored in ice-cores, compared to that stored in speleothems. Both speleothems and ice-core records show damping effects on decadal time scales, which can in part be attributed to the temporal resolution of the individual records. This comparison of different proxy archives to isotope-enabled GCM output shows a promising way to evaluate the model’s capability to resolve δ18O variability.</p> <div> <div> <div> <p>[1]  Bühler, J. C. et al. Comparison of the oxygen isotope signatures in speleothem records and iHadCM3 model simulations for the last millennium. Climate of the Past: Discussions 1–30 (2020).</p> <p>[2]  Tindall, J. C., Valdes, P. J. & Sime, L. C. Stable water isotopes in HadCM3: Isotopic signature of El Niño-Southern Oscillation and the tropical amount effect. Journal of Geophysical Research Atmospheres 114, 1–12 (2009).</p> <p>[3] Konecky, B. L. et al. The Iso2k database: A global compilation of paleo-δ18O and δ2H records to aid understanding of Common Era climate. Earth System Science Data 12, 2261–2288 (2020).</p> </div> </div> </div> </div> </div> </div>

scholarly journals Volcanic Fluxes Over the Last Millennium as Recorded in the Gv7 Ice Core (Northern Victoria Land, Antarctica)

Geosciences ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 38 ◽  
Author(s):  
Raffaello Nardin ◽  
Alessandra Amore ◽  
Silvia Becagli ◽  
Laura Caiazzo ◽  
Massimo Frezzotti ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Deposition Flux ◽  
Last Millennium ◽  
Regional Variability ◽  
High Accumulation ◽  
Continental Scale ◽  
Victoria Land

Major explosive volcanic eruptions may significantly alter the global atmosphere for about 2–3 years. During that period, volcanic products (mainly H2SO4) with high residence time, stored in the stratosphere or, for shorter times, in the troposphere are gradually deposited onto polar ice caps. Antarctic snow may thus record acidic signals providing a history of past volcanic events. The high resolution sulphate concentration profile along a 197 m long ice core drilled at GV7 (Northern Victoria land) was obtained by Ion Chromatography on around 3500 discrete samples. The relatively high accumulation rate (241 ± 13 mm we yr −1) and the 5-cm sampling resolution allowed a preliminary counted age scale. The obtained stratigraphy covers roughly the last millennium and 24 major volcanic eruptions were identified, dated, and tentatively ascribed to a source volcano. The deposition flux of volcanic sulphate was calculated for each signature and the results were compared with data from other Antarctic ice cores at regional and continental scale. Our results show that the regional variability is of the same order of magnitude as the continental one.

scholarly journals Volcanic fluxes over the last millennium as recorded in the GV7 ice core (Northern Victoria Land, Antarctica)

2020 ◽  
Author(s):  
Rita Traversi ◽  
Silvia Becagli ◽  
Mirko Severi ◽  
Raffaello Nardin ◽  
Laura Caiazzo ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Deposition Flux ◽  
Last Millennium ◽  
Regional Variability ◽  
High Accumulation ◽  
Continental Scale ◽  
Victoria Land

<p>Explosive volcanic eruptions are able to affect significantly the atmosphere for 2‐3 years. During this time, volcanic products (mainly H2SO4) with high residence 
time are stored in the stratosphere/troposphere, and eventually deposited onto polar ice caps; snow layers may thus record signals providing a history of past 
volcanic events. A high resolution sulphate concentration profile along a 197 m long ice core drilled at GV7 (Northern Victoria Land) was obtained by Ion Chromatography. The relatively high accumulation rate (241±13 mm we yr<sup>-1</sup>) and the 5‐cm resolution allowed a preliminary counted age scale. The obtained stratigraphy covers roughly the last millennium and 24 major volcanic eruptions were identified, dated and 
ascribed to a source volcano. The deposition flux of volcanic sulfate was calculated and the results were compared with data from other Antarctic ice cores at regional and continental scale. Our results show that the regional variability is of the same order of magnitude 
of the continental scale.</p>

scholarly journals Precipitation regime and stable oxygen isotopes at Dome C, East Antarctica – a comparison of two extreme years 2009 and 2010

2015 ◽  
Vol 15 (21) ◽  
pp. 30473-30509
Author(s):  
E. Schlosser ◽  
B. Stenni ◽  
M. Valt ◽  
A. Cagnati ◽  
J. G. Powers ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Ice Core ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Atmospheric Model ◽  
Stable Isotope Ratios ◽  
Stable Water Isotopes ◽  
Precipitation Regime ◽  
Meridional Transport ◽  
Measuring Period

Abstract. At the East Antarctic deep ice core drilling site Dome C, daily precipitation measurements have been initiated in 2006 and are being continued until today. The amounts and stable isotope ratios of the precipitation samples as well as crystal types are determined. Within the measuring period, the two years 2009 and 2010 showed striking contrasting temperature and precipitation anomalies, particularly in the winter seasons. The reasons for these anomalies and their relation to stable isotope ratios are analysed using data from the mesoscale atmospheric model WRF (Weather Research and Forecasting Model) run under the Antarctic Mesoscale Prediction System (AMPS). 2009 was relatively warm and moist due to frequent warm air intrusions connected to amplification of Rossby waves in the circumpolar westerlies, whereas the winter of 2010 was extremely dry and cold. It is shown that while in 2010 a strong zonal atmospheric flow was dominant, in 2009 an enhanced meridional flow prevailed, which increased the meridional transport of heat and moisture onto the East Antarctic plateau and led to a number of high-precipitation/warming events at Dome C. This was also evident in a positive (negative) SAM index and a negative (positive) ZW3 index during the winter months of 2010 (2009). Changes in the frequency or seasonality of such event-type precipitation can lead to a strong bias in the air temperature derived from stable water isotopes in ice cores.

Tephra in the Greenland Ice cores: Insights into Icelandic volcano-climate impacts

2021 ◽  
Author(s):  
Imogen Gabriel ◽  
Gill Plunkett ◽  
Peter Abbott ◽  
Bergrún Óladóttir ◽  
Joseph McConnell ◽  
...  
Keyword(s):  
High Resolution ◽  
Ice Core ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Climate Impacts ◽  
Geochemical Analysis ◽  
Volcanic Events ◽  
Societal Impacts ◽  
The Impact ◽  
Ice Core Records

<p>Volcanic eruptions are considered as one of the primary natural drivers for changes in the global climate system and understanding the impact of past eruptions on the climate is integral to adopt appropriate responses towards future volcanic eruptions.</p><p>The Greenland ice core records are dominated by Icelandic eruptions, with several volcanic systems (Katla, Hekla, Bárðarbunga-Veiðivötn and Grimsvötn) being highly active throughout the Holocene. A notable period of increased Icelandic volcanic activity occurred between 500-1250 AD and coincided with climatic changes in the North Atlantic region which may have facilitated the Viking settlement of Greenland and Iceland. However, a number of these volcanic events are poorly constrained (duration and magnitude). Consequently, the Greenland ice cores offer the opportunity to reliably reconstruct past Icelandic volcanism (duration, magnitude and frequency) due to their high-resolution, the proximity of Iceland to Greenland and subsequent increased likelihood of volcanic fallout deposits (tephra particles and sulphur aerosols) being preserved. However, both the high frequency of eruptions between 500-1250 AD and the geochemical similarity of Iceland’s volcanic centres present challenges in making the required robust geochemical correlations between the source volcano and the ice core records and ultimately reliably assessing the climatic-societal impacts of these eruptions.</p><p>To address this, we use two Greenland ice core records (TUNU2013 and B19) and undertake geochemical analysis on tephra from the volcanic events in the selected time window which have been detected and sampled using novel techniques (insoluble particle peaks and sulphur acidity peaks). Further geochemical analysis of proximal material enables robust correlations to be made between the events in the ice core records and their volcanic centres. The high-resolution of these polar archives provides a precise age for the event and when utilised alongside other proxies (i.e. sulphur aerosols), both the duration and magnitude of these eruptions can be constrained, and the climatic-societal impacts of these eruptions reliably assessed.</p>

scholarly journals A 40 Year Record in an Ice Core from the Dunde Ice Cap, China (Abstract)

1988 ◽  
Vol 10 ◽  
pp. 221 ◽  
Author(s):  
Wu Xiaoling ◽  
Lonnie G. Thompson
Keyword(s):  
Oxygen Isotope ◽  
Ice Core ◽  
Field Work ◽  
Tibet Plateau ◽  
Ice Thickness ◽  
Ice Cap ◽  
Pulse Radar ◽  
The North ◽  
Isotope Profile ◽  
Isotope Content

A cooperative glacio-climatological ice-core drilling and analysis program, administered by LIGC and BPRC, has been carried out since 1984. The major objective of this study is to extract from the Dunde ice cap records of the general environmental conditions, which include drought, volcanic activity, moisture sources, glacier net balance and possibly temperature over the last 3000 years. In 1984 a group of 18 Chinese scientists and an American scientist spent 6 weeks on the Dunde ice cap. The central objective of their research was to evaluate the potential of the ice cap to yield a lengthy ice-core climate record. Results of the 1984 field work and 1985 laboratory analysis are submitted here. The Dunde ice cap (38°96′N, 96°24.5′E) is located in the north-eastern section of the Tibet plateau, China. Its length is 10.9 km; the width varies from 2.5 to 7.5 km. The total area of the ice cap is 57 km2. A 16 m core was drilled at the first site, located on a flat part of the ice cap, 5150 m a.s.l. A 10.2 m ice core was drilled at the ice cap summit (5300 m). A series of shallow cores and 2 m pits were excavated at each of the two sites and in the lower section of the ice cap. A mono-pulse radar unit was used to determine ice thickness. The ice thickness ranged between 94 and 167 m, with an average thickness of 140 m. Using a thermistor cable, minimum temperatures of −9.1° and −9.5 °C were measured in the 16 m hole and 10.2 m hole respectively. Microparticle analysis of the ice core from the Dunde ice cap revealed a very high dust content, on average 16 × 105 particles (≥0.63 to ≤16 μ in diameter) per ml of sample, i.e. 3−4 times higher than the microparticle content in the Quelccaya ice cap, Peru, and 100 times higher than in the core from Byrd Station, Antarctica. Oxygen-isotope content ranged between −12 and −14 per mil. Initially it was anticipated that the oxygen-isotope content would produce a more negative value in the Dunde ice cap. More work is required to explain the mechanism controlling δ18o variation in the ice core from the Dunde ice cap. The microparticles, oxygen-isotope content, conductivity, and tritium measurements, together with stratigraphy, temperature and density, are presented in the figures. The 40 year net-balance record reconstructed from the ice-core and oxygen-isotope profile is in good agreement with data from precipitation and major temperature trends obtained for the last 30 years from Delingha meteorological station, which is located 160 km south-east of the ice cap.

scholarly journals Temperature and mineral dust variability recorded in two low-accumulation Alpine ice cores over the last millennium

2018 ◽  
Vol 14 (1) ◽  
pp. 21-37 ◽  
Author(s):  
Pascal Bohleber ◽  
Tobias Erhardt ◽  
Nicole Spaulding ◽  
Helene Hoffmann ◽  
Hubertus Fischer ◽  
...  
Keyword(s):  
Time Series ◽  
Mineral Dust ◽  
Ice Core ◽  
Ice Cores ◽  
Temperature Reconstruction ◽  
Relative Increase ◽  
Ice Age ◽  
European Alps ◽  
Stable Water Isotopes ◽  
Annual Layer

Abstract. Among ice core drilling sites in the European Alps, Colle Gnifetti (CG) is the only non-temperate glacier to offer climate records dating back at least 1000 years. This unique long-term archive is the result of an exceptionally low net accumulation driven by wind erosion and rapid annual layer thinning. However, the full exploitation of the CG time series has been hampered by considerable dating uncertainties and the seasonal summer bias in snow preservation. Using a new core drilled in 2013 we extend annual layer counting, for the first time at CG, over the last 1000 years and add additional constraints to the resulting age scale from radiocarbon dating. Based on this improved age scale, and using a multi-core approach with a neighbouring ice core, we explore the time series of stable water isotopes and the mineral dust proxies Ca2+ and insoluble particles. Also in our latest ice core we face the already known limitation to the quantitative use of the stable isotope variability based on a high and potentially non-stationary isotope/temperature sensitivity at CG. Decadal trends in Ca2+ reveal substantial agreement with instrumental temperature and are explored here as a potential site-specific supplement to the isotope-based temperature reconstruction. The observed coupling between temperature and Ca2+ trends likely results from snow preservation effects and the advection of dust-rich air masses coinciding with warm temperatures. We find that if calibrated against instrumental data, the Ca2+-based temperature reconstruction is in robust agreement with the latest proxy-based summer temperature reconstruction, including a “Little Ice Age” cold period as well as a medieval climate anomaly. Part of the medieval climate period around AD 1100–1200 clearly stands out through an increased occurrence of dust events, potentially resulting from a relative increase in meridional flow and/or dry conditions over the Mediterranean.

scholarly journals Mapping the suitability for ice-core drilling of glaciers in the European Alps and the Asian High Mountains

2017 ◽  
Vol 64 (243) ◽  
pp. 12-26 ◽  
Author(s):  
ROBERTO GARZONIO ◽  
BIAGIO DI MAURO ◽  
DANIELE STRIGARO ◽  
MICOL ROSSINI ◽  
ROBERTO COLOMBO ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Weight Of Evidence ◽  
European Alps ◽  
High Mountains ◽  
Mountain Glacier ◽  
Past Climate ◽  
Core Drilling ◽  
Mountain Glaciers

ABSTRACTIce cores from mid-latitude mountain glaciers provide detailed information on past climate conditions and regional environmental changes, which is essential for placing current climate change into a longer term perspective. In this context, it is important to define guidelines and create dedicated maps to identify suitable areas for future ice-core drillings. In this study, the suitability for ice-core drilling (SICD) of a mountain glacier is defined as the possibility of extracting an ice core with preserved stratigraphy suitable for reconstructing past climate. Morphometric and climatic variables related to SICD are selected through literature review and characterization of previously drilled sites. A quantitative Weight of Evidence method is proposed to combine selected variables (i.e. slope, local relief, temperature and direct solar radiation) to map the potential drilling sites in mid-latitude mountain glaciers. The method was first developed in the European Alps and then applied to the Asian High Mountains. Model performances and limitations are discussed and first indications of new potential drilling sites in the Asian High Mountains are provided. Results presented here can facilitate the selection of future drilling sites especially on unexplored Asian mountain glaciers towards the understanding of climate and environmental changes.

First continuous high-resolution aerosol record from the East Greenland Ice Core Project (EGRIP), covering the last 15,000 years

2020 ◽  
Author(s):  
Camilla Marie Jensen ◽  
Tobias Erhardt ◽  
Giulia Sinnl ◽  
Hubertus Fischer
Keyword(s):  
High Resolution ◽  
Biomass Burning ◽  
Forest Fires ◽  
Ice Core ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Background Level ◽  
Volcanic Eruptions ◽  
Atmospheric Conditions ◽  
Data Set

<p>Ice sheets are reliable archives of atmospheric impurities such as aerosols and gasses of both natural and anthropogenic origin. Impurity records from Greenland ice cores reveal much information about previous atmospheric conditions and long-range transport in the Northern hemisphere going back more than a hundred thousand years.</p><p>Here we present the data from the upper 1,411 m from the EGRIP ice core, measuring conductivity, dust, sodium, calcium, ammonium, and nitrate. These records contain information about ocean sources, transport of terrestrial dust, soil and vegetation emissions as well as biomass burning, volcanic eruptions, etc., covering approximately the past 15,000 years. This newly obtained data set is unique as it provides the first high-resolution information about several thousands of years of the mid-Holocene period in Greenland that none of the previous impurity records from the other deep Greenland ice cores had managed to cover before due to brittle ice. This will contribute to further understanding of the atmospheric conditions for the pre-industrial period.</p><p>The ammonium record contains peaks significantly higher than the background level. These peaks are caused by biomass burning or forest fires emitting plumes of ammonia large enough so that they can extend to the free troposphere and be efficiently transported all the way to the Greenland ice sheet. Here we present preliminary results of the wild fire frequency covering the entire Holocene, where the wild fires are defined as outliers in the ammonium record of annual means.</p>

A multiproxy approach to identify the Tambora volcanic fallout in 1810s from the Styx glacier in Victoria Land, Antarctica

2020 ◽  
Author(s):  
Changhee Han ◽  
Songyi Kim ◽  
Yeongcheol Han ◽  
Jangil Moon ◽  
Sang-Bum Hong ◽  
...  
Keyword(s):  
Inner Core ◽  
Major Ions ◽  
Ice Core ◽  
Ice Cores ◽  
Isotope Ratios ◽  
Depth Interval ◽  
Additional Time ◽  
Aerosol Composition ◽  
Annual Layer ◽  
Victoria Land

<p>Ice cores provide records of past aerosol composition and have been used to reconstruct the relative contribution of different emission sources changing in time. A precise age scale is essential to achieve this goal, for which annual layer counting of seasonal cycles in water stable isotope ratios (δ<sup>18</sup>O and δD) and major ion concentrations have been basically utilized. Introducing additional time markers are helpful for reducing the uncertainty of the depth-age scale, and the fallout of volcanic products has offered useful time markers when they are well-dated. Here, we report lead isotope ratios (<sup>206</sup>Pb/<sup>207</sup>Pb and <sup>208</sup>Pb/<sup>207</sup>Pb) and concentrations of thallium (Tl) and major ions in a shallow ice core from the Styx Glacier (73°51 S, 163°41 E) in the Victoria Land, Antarctica, analyzed for discriminating volcanic products of the 1815 AD Tambora eruption, Indonesia from local volcanic inputs. Mechanically decontaminated 19 inner core pieces between the depth interval 40.8 – 42.4 m were analyzed. The results show that the increases of volcanic SO<sub>4</sub><sup>2-</sup> input are accompanied by either (1) input of more-radiogenic lead (higher <sup>206</sup>Pb/<sup>207</sup>Pb) and Tl or (2) relatively <sup>208</sup>Pb enriched lead. These results suggest that the Tambora volcanic input is overprinted by local volcanic aerosol input and that the isotope-based assessment of the Pb sources can help to discriminate between remote and local components of the volcanic input signals recorded in Victoria Land glaciers.</p>

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