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Evidence of general instability of past climate from a 250-kyr ice-core record

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Dansgaard WS
Dansgaard WS
Dansgaard WS
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S. J. Johnsen
S. J. Johnsen
S. J. Johnsen
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H. B. Clausen
H. B. Clausen
H. B. Clausen
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Dorthe Dahl-Jensen at University of Copenhagen
Dorthe Dahl-Jensen
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Abstract

A detailed stable-isotope record is presented for the full length of the Greenland Ice-core Project Summit ice core covering the last 250,000 years according to a graduated timescale. It appears that the climatic stability of the Holocene is the exception rather than the rule; the last interglacial is also noted to have lasted longer than is implied by the deep-sea SPECMAP record. This discrepancy may be accounted for if the climate instability at the outset of the last interglacial delayed the melting of the Saalean ice sheets in America and Eurasia.
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© 1993Nature Publishing Group
© 1993Nature Publishing Group
© 1993Nature Publishing Group

Supplementary resource (1)

GRIP Oxygen Isotopes
Data
January 1999
Sigfus J Johnsen
... The sub-Antarctic zone controlled the study area, which corresponded to the high abundance of cold-water species during the MIS 3 period. This is corroborated by two ice cores drilled in central Greenland, where oxygen isotope records show that MIS3 was not a classical interglacial; cold stadial climatic conditions are abrupt transitions to a mild interstadial, eventually followed by a return to cold stadial conditions (Dansgaard et al., 1993). In addition, the polar planktic foraminifera are abundant, and their isotopic ratios correspond with a cold and turbulent climate in the North Atlantic Ocean during MIS 3 (Bond and Lotti, 1995). ...
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The Agulhas Return Current (ARC) transports warm tropical and subtropical waters eastward into the southern Indian Ocean. It plays a crucial role in the oceanographic connections between the Indian, Atlantic, and Southern oceans. Modern oceanographic observations show that the latitudinal position of the ARC varies interannually. However, its historical positional variations remain poorly understood. Calcareous nannofossils can be a good indicator of ancient current migration, although their record in the Southwest Indian Ocean is poorly studied. This research aims to understand the characteristics and downcore variation of the calcareous nannofossil assemblages and trace the record of the ancient ARC. To achieve these goals, this study analyzed pelagic sediments of multicore 34IV-SWIR-S021MC03, 34IV-SWIR-S032MC04, and 34IV-SWIR-S040MC05 from the Southwest Indian Ocean. A total of 13 nannofossil species have been identified. The assemblages belong to the subtropical convergence zone regime. They are characterized by warm and cold water species, dominated by Emiliania huxleyi , Calcidiscus leptoporus , Gephyrocapsa muellerae, and Florisphaera profunda . According to the AMS ¹⁴ C age model and phytoplankton ecological signatures, this study establishes a calcareous nannofossil indicator to trace the migration of the ancient ARC during the last 40 kyr. The result shows three periods of migration: 40–22 kyr, the ancient ARC was in the far north and was moving southward; 22–14 kyr, a transitional period, the ancient ARC was moving northward; 14–3 kyr, the ARC was moving southward. This further suggests that the migration of the ancient ARC is more complex than the two recognized phases, and there were essential turning points around the last glacial maximum period. It also acknowledges that the ancient ARC is sensitive to interglacial periods and can be influenced simultaneously by the Southern Hemisphere monsoon and westerly winds.
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... in Greenland (Andersen et al., 2004;Dansgaard et al., 1993;Wolff et al., 2010). In general, decreased Greenland air temperatures during stadials (more negative δ 18 O values in ice cores) are associated with a southward shift of the Intertropical Convergence Zone (ITCZ) resulting in a weakening of the Indian summer monsoon reflected by an increase in aeolian contribution and grain size in sediments from the northeastern Arabian Sea (Deplazes et al., 2014). ...
The Toba Eruption 74,000 Years ago Strengthened the Indian Winter Monsoon‐Evidence From Coccolithophores
Article
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The global impact of the Youngest Toba Tuff (YTT) supereruption is still heavily debated, ranging from having little effects on climate to significantly affecting modern human evolution. Climate models and proxy records show that the eruption may have caused cooling of the Asian landmass, thus impacting regional climate such as the Indian monsoon system. However, the immediate effect of the eruption on the Indian monsoon has not been indisputably demonstrated in any proxy record. Here, we present a paleo‐primary productivity (PP) record in core SO130‐289KL from the northeastern Arabian Sea based on the coccolithophore species Florisphaera profunda transfer function. Florisphaera profunda decreased from ∼30% before the YTT eruption to ∼8% right after the YTT eruption, which translates to an increase in PP by ∼65% from a long‐term average of ∼200 gC/m²/yr for about 8–19 years after the eruption. The duration was estimated using a new error‐weighted mean age of the YTT eruption (73.9 ± 0.1 ka, 2σ uncertainties) based on recent age estimates from ice cores, radiometric dating, and speleothem records. The elevated PP is most likely linked to the deepening of the surface ocean mixed layer driven by strengthened northeasterly Indian winter monsoon winds. This hypothesis is supported by stable oxygen isotope records from speleothem and ice cores, which show indications of a strengthening of the Indian winter monsoon during times of increased PP. Our results support previous modeling studies and provide unequivocal evidence from a marine record for an Indian monsoon response to the supereruption.
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... However, orbitaland millennial-scale climate variability remains poorly constrained across the iNHG, especially within continental interior settings that host much of the present global population. Millennial variability in mean annual air temperature oscillations throughout the last glacial cycle is reconstructed from Greenland ice cores (i.e., Dansgaard-Oeschger cycles) 12 and from multiple centennialresolution records from the North Atlantic Ocean, Mediterranean, Iberian margin, Balkan Peninsula (Lake Ohrid), and Chinese Loess Plateau (CLP) throughout the last 1.5 million years (Myr) [13][14][15][16] . However, millennial climate variability before 1.5 Ma remains underexplored in both oceanic and terrestrial settings. ...
Orbital- and millennial-scale Asian winter monsoon variability across the Pliocene–Pleistocene glacial intensification
Article
Full-text available
  • Apr 2024
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New Insights Into the Surface‐Ocean Dynamics of the Northeastern Atlantic Ocean Across the Marine Isotope Stage 7
Article
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  • May 2024
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Glacial-interglacial sedimentation control on gas seepage exemplified by Vestnesa Ridge off NW Svalbard margin
Article
Full-text available
  • Apr 2024
Vestnesa Ridge is built-up of thick contourites mainly deposited during the last ∼5 million years. Methane leaks from deep gas reservoirs creating pockmarks on its crest, and which have been the focus of numerous studies. Sedimentation patterns in relation to the pronounced changes in oceanography and climate of the last glacial-interglacial cycles and its possible impact of seepage of gas have rarely been studied. Here, we present a detailed history of contourite development covering the last ∼130,000 years with most details for the last 60,000 years. The study is based on 43 marine sediment cores and 1,430 km of shallow seismic lines covering the ridge including methane seep sites, with the purpose of reconstructing changes in depositional patterns in relation to paleoceanographical changes on glacial, interglacial, and millennial time scale in relation to activity of seepage of gas. The results show that thick Holocene deposits occurred below ∼1,250 m water depth in the western part of the ridge. Both in pockmarks at western and eastern Vestnesa Ridge, seepage decreased at ∼10–9 ka in the early Holocene. The fine Holocene mud likely reduced seepage to a slow diffusion of gas and microbial oxidation probably prevented escape from the seafloor. Results also showed that seepage of gas was highly variable during the glacial, and low to moderate during the cold Heinrich stadial H1 (19–15 ka) and Younger Dryas stadial (13–12 ka). Seepage reached a maximum during the deglaciation in the Bølling and Allerød interstadials 15–13 ka and early Holocene 12–10 ka. The deglaciation was a period of rapid climatic, oceanographic, and environmental changes. Seepage of gas varied closely with these events indicating that slower tectonic/isostatic movements probably played a minor role in these millennial scale rapid fluctuations in gas emission.
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Causes of Uncertainties in Paleoclimatic Reconstructions Based on the Oxygen Isotope Composition of Glacier Ice on Elbrus (Western Plateau)
Article
  • Oct 2023
Received July 28, 2023; revised September 2, 2023; accepted October 2, 2023A study of the isotope signature of glacial ice in the Western Elbrus Plateau (the Caucasus) was made on the basis of five ice cores obtained in different years with high resolution. It was shown that the isotopic characteristics of ice are associated with the processes of accumulation and wind scouring of snow. Three ice cores were obtained in 2013 (C–1, C–2 and C–3), one in 2017 (C–4) and one more in 2018 (C–5). Core sampling was performed with a resolution of 5 cm. Isotopic analysis was done at the CERL laboratory (AARI) using a Picarro L2130-i isotope analyzer, the accuracy was 0.06‰ for δ18О and 0.30‰ for δ2Н. The values of δ18О and δ2Н of the ice of the Western Plateau generally vary from –5 to –30‰ and from –18.7 to –225.8‰, respectively, with well-defined seasonality. Comparison of the isotope record for all cores showed that the differences in accumulation for individual seasons reach 0.3 m w. eq., differences in accumulation for individual seasons averaged over 5 years is approximately 0.2 m w.eq. The absolute differences in the average seasonal values of δ18O associated with wind scouring and spatial redistribution of snow (deposition noise), averaged over 5 years, reached 1.38‰. The irregularity of precipitation amount within the season and errors in core dating are an additional contribution to non-climate variance (noise of definition). The absolute difference in the average seasonal values of δ18О associated with this type of noise averaged over 5 years is 1.7‰. Thus, the total uncertainty for two different types of noise can be estimated at 2.2‰, which is about 20% of the annual seasonal amplitude of δ18O values of the glacier ice in the Western Plateau (the average difference between the δ18O values of warm and cold seasons is ~10–11‰). One of the problems of linking the isotope record to the annual temperature record at the weather station was solved by using ammonium concentrations for dating the C-1 ice core and calculating the “ideal” annual variation of δ18O values by a cosine function of the annual amplitude. Using ammonium ion (\({\text{NH}}_{4}^{ + }\)) concentration each annual layer in C-1 ice core was divided into two parts associated to snow deposition in winter and in summer. It also showed δ18O values associated to change of seasons. The calculation of the cosine function showed the simplified δ18O values for each month of a particular year, due to which the δ18O values of the season boundaries in the ice core were linked to calendar months. This assimilation allowed us to compare the obtained average seasonal values of δ18О from the core with instrumental observations at the Klukhorskiy Pass meteorological station. The δ18O values of winter seasons have a weak relationship with surface temperatures, not only due to wind erosion, but also due to the high interannual variability of snow accumulation. At the same time, the average δ18O values of the warm seasons are significantly positive correlated with surface temperature (r = 0.7, p = 0.1), so ice core δ18O records can be used as a temperature proxy of the warm period.
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The origin of Arctic precipitation under present and glacial conditions
Article
Full-text available
  • Sep 1989
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Climate instability during the last Interglacial period recorded in the GRIP ice core
Article
Full-text available
  • Jul 1993
Isotope and chemical analyses of the GRIP ice core from Summit, central Greenland, reveal that climate in Greenland during the last interglacial period was characterized by a series of severe cold periods, which began extremely rapidly and lasted from decades to centuries. As the last interglacial seems to have been slightly warmer than the present one, its unstable climate raises questions about the effects of future global warming.
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Abrupt Color Changes in Isotope Stage 5 in North Atlantic Deep Sea Cores: Implications for Rapid Change of Climate-Driven Events
Chapter
  • Jan 1992
Digitized records of optical density in many North Atlantic cores exhibit rapid changes from lighter to darker extremes, typically within less than 200 years, at the 5d/5e, 5b/5c and 4/5 boundaries. In cores from DSDP site 609 the changes from lighter to darker color coincide with increases in relative abundance of N. pachyderma (l. c.), with increases in abundances of lithic grains and with decreases in carbonate content. The rapid changes to dark color, therefore, are climate-driven and correspond to a lowering of sea surface temperatures and to increases in amounts of ice rafted debris relative to biogenic carbonate. At the 5d/5c boundary, δ18O in N. pachvderma (l.c.) increases abruptly with the change to darker sediment as expected for cooler sea surface temperatures. At the 4/5 boundary, however, δ18O decreases with the change to darker sediment and cooler sea surface temperatures, suggesting that a layer of fresh surface water was present in the North Atlantic at that time.
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A Battery Powered, Instrumented Deep Ice Core Drill for Liquid Filled Holes
Article
  • Jan 1985
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The ‘flickering switch’ of Late Pleistocene climate change
Article
  • Feb 1993
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Speculation about the Next Glaciation
Article
  • Nov 1972
A spectacular 10‰ drop in the ratio (δ) in precipitation indicative of rapid cooling occurred at Camp Century, Greenland, 89,500 y.a. The timing is based upon an assumption of δ periodicity being constant in time. Onset of the Wisconsin pleniglacial is reflected by 6‰ δ drop at 73,000 BP. Similar event might have occurred 109,000 y.a., but the core at corresponding depth is missing. Could it also happen today?
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Maximum Entropy Spectral Analysis and Autoregressive Decomposition
Article
  • Feb 1975
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Description and ESR dating of the Holsteinian Interglaciation
Article
  • Dec 1985
  • QUATERNARY SCI REV
The classical region of the Holsteinian interglacial is in the vicinity of Hamburg and the Lower Elbe. It is defined on the basis of pollen and is clearly distinguishable from the Eemian interglacial (Hallik, 1960; Müller, 1974). The Holsteinian interglacial is represented by a sequence of sediments up to 100 m in thickness. These consist of limnic, fluvial, and marine beds and show a transgression up to the height of present sea-level. Twenty-seven molluscs from Holsteinian deposits were used for ESR dating. The ages show that the Holsteinian may be correlated with stage 7 of the deep sea record V28-238 (Shackleton and Opdyke, 1973).
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Late-Glacial Climate History from Ice Cores
Article
  • Jan 1984
Ice cores contain information on climatic variations and their causes. Recent results obtained on the new deep ice core drilled in 1981 at Dye 3, South Greenland, in the frame of the US-Danish-Swiss Greenland Ice Sheet Program are: Comparison of the δ 180 variations in the Greenland ice cores with those in European lake carbonate exhibits strong similarities and provides time marks (13,000, 11,000, 10,000 B.P.) for the Late-Glacial section of the ice cores; CO2 concentration measurements in the occluded air indicate low (180–200 ppm) CO2 concentrations 30,000 to 15,000 B.P. and an increase to ca. 300 ppm around 13,000 B.P.,. The CO2 increase might reflect a change in the ocean circulation at the end of the last glaciation and could have contributed to the establishment of the Holocene environmental conditions; 10Be concentration measurements on samples covering the last 50,000 yaers show a correlation with δ 180, low δ 180 values corresponding to high 10Be concentrations (atoms per g of ice). Probably this mainly reflects changes in the rate of precipitation in the northern hemisphere. Based on the ice core information climatic events during the Glacial-Postglacial transition are discussed.
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Irregular glacial interstadials recorded in a new Greenland ice core
Article
  • Sep 1992
  • NATURE
Profiles of O-18/O-16 ratios along three previous deep Greenland ice cores seemed to reveal irregular but well-defined episodes of relatively mild climate conditions (interstadials) during the mid and late parts of the last glaciation. Results are presented from a new deep ice core drilled at the summit of the Greenland ice sheet, where the depositional environment and the flow pattern of the ice are close to ideal for core recovery and analysis. The results reproduce the previous findings to such a degree that the existence of the interstadial episodes can no longer be in doubt. According to a preliminary timescale based on stratigraphic studies, the interstadials lasted from 500 to 2000 yrs; their irregular occurrence suggests complexity in the behavior of the North Atlantic ocean circulation.
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