Atmospheric Lead in Antarctic Ice during the Last Climatic Cycle

Concentrations of lead (Pb) have been measured by the ultra-clean isotope dilution mass spectrometry technique in various sections of the Antarctic Dome C and Vostok deep ice cores, whose ages range from 3.85 to 155 ka B.P., in order to assess the natural, pre-human, sources of this toxic heavy metal in the global troposphere. Pb concentrations were very low, as low as about 0.3 pg Pb/g during the Holocene and probably during the last interglacial and part of the last ice age. On the other hand, they were quite high, up to about 40 pg Pb/g, during the Last Glacial Maximum and at the end of the penultimate ice age. Wind-blown dust from crustal rock and soil appears to be the main natural source of Pb in the global troposphere. Pb contribution from volcanoes is significant during periods of low Pb only. Contribution from the oceans is insignificant.

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Enhanced Moisture Delivery into Victoria Land, East Antarctica During the Early Last Interglacial: Implications for West Antarctic Ice Sheet Stability

10.5194/cp-2021-7 ◽

2021 ◽

Author(s):

Yuzhen Yan ◽

Nicole E. Spaulding ◽

Michael L. Bender ◽

Edward J. Brook ◽

John A. Higgins ◽

...

Keyword(s):

Accumulation Rate ◽

Ice Cores ◽

Snow Accumulation ◽

East Antarctica ◽

Ice Age ◽

Accumulation Rates ◽

Last Interglacial ◽

Ice Shelf ◽

Ross Ice Shelf ◽

Victoria Land

Abstract. The S27 ice core, drilled in the Allan Hills Blue Ice Area of East Antarctica, is located in Southern Victoria Land ~80 km away from the present-day northern edge of the Ross Ice Shelf. Here, we utilize the reconstructed accumulation rate of S27 covering the Last Interglacial (LIG) period between 129 and 116 thousand years before present (ka) to infer moisture transport into the region. The accumulation rate is based on the ice age-gas age differences calculated from the ice chronology, which is constrained by the stable water isotopes of the ice, and an improved gas chronology based on measurements of oxygen isotopes of O2 in the trapped gases. The peak accumulation rate in S27 occurred at 128.2 ka, near the peak LIG warming in Antarctica. Even the most conservative estimate yields a six-fold increase in the accumulation rate in the LIG, whereas other Antarctic ice cores are typically characterized by a glacial-interglacial difference of a factor of two to three. While part of the increase in S27 accumulation rates must originate from changes in the large-scale atmospheric circulation, additional mechanisms are needed to explain the large changes. We hypothesize that the exceptionally high snow accumulation recorded in S27 reflects open-ocean conditions in the Ross Sea, created by reduced sea ice extent and increased polynya size, and perhaps by a southward retreat of the Ross Ice Shelf relative to its present-day position near the onset of LIG. The proposed ice shelf retreat would also be compatible with a sea-level high stand around 129 ka significantly sourced from West Antarctica. The peak in S27 accumulation rates is transient, suggesting that if the Ross Ice Shelf had indeed retreated during the early LIG, it would have re-advanced by 125 ka.

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When Will the Present Interglacial End?

Quaternary Research ◽

10.1016/0033-5894(72)90056-7 ◽

1972 ◽

Vol 2 (3) ◽

pp. 341-349 ◽

Cited By ~ 17

Author(s):

Nils-Axel Mörner

Keyword(s):

Climatic Conditions ◽

Ice Age ◽

Last Interglacial ◽

The Third ◽

The Future ◽

Last Ice Age

We are now living under interglacial climatic conditions, the Present Interglacial or Flandrian Interglacial Age. It will certainly be followed by the Future Ice Age. The major cold/warm changes seem to have a cyclicity of 10,500 yr. We have been in the second cycle (characterized by cooler climate) after the Last Ice Age for 2200 yr and will continue to be so for another 8300 yr. By analogy with the conditions during the Last Interglacial it is concluded that this cycle will remain moderately warm. With the end of the third cycle at about 18,800 years AP, the Present Interglacial will end and the First Future Glacial Age begin. Further information about the climatic conditions during the “cold” cycle 117,700–107,200 y. a. is necessary, however, before a really well-founded prediction can be made.

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10Be Concentrations in Antarctic Ice

Annals of Glaciology ◽

10.3189/s0260305500004456 ◽

1988 ◽

Vol 10 ◽

pp. 200-200

Author(s):

J. Beer ◽

H. Oeschger ◽

G. Bonani ◽

M. Suter ◽

W. Wölfli

Keyword(s):

Production Rate ◽

Atmospheric Circulation ◽

Ice Cores ◽

Ice Age ◽

Solar Modulation ◽

Short Term ◽

Cosmogenic Isotope ◽

Last Ice Age ◽

Low Precipitation ◽

Good Agreement

Measurements of the cosmogenic isotope 10Be (T½ = 1.5 Ma) on Greenland ice cores produced interesting results. Variations in the 10Be concentrations can be interpreted in terms of changes in the production rate and in atmospheric circulation and deposition. During the Holocene, good agreement between short-term variations in 10Be and 14C indicates that the production rate of both isotopes was changing, probably due to solar modulation.During the last ice age, periods with significantly higher 10Be concentrations are observed. The good anti-correlation between 10Be and δ18O suggests that these intervals correspond to periods of low precipitation rates.Work on Antarctic ice cores is in progress, but only relatively few 10Be data have been published yet. 10 Be results from Antarctic ice cores are presented and compared with data from Greenland.

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Ice cores and climatic change

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1977.0103 ◽

1977 ◽

Vol 280 (972) ◽

pp. 143-168 ◽

Cited By ~ 141

Keyword(s):

Ice Sheets ◽

Ice Cores ◽

Ice Age ◽

Isotopic Ratios ◽

Temperature Profiles ◽

Physical Processes ◽

Similar Relation ◽

Stable Isotopic ◽

Last Ice Age ◽

Glacial Periods

The paper deals primarily with the use of stable isotopic ratios to determine the former climate of ice sheets. Studies of temperature profiles throughout ice sheets have shown that for at least several thousand years, changes of isotopic δ ratios have been proportional to changes of surface temperatures; this relationship is discussed in terms of the physical processes involved. It is considered reasonable to use a similar relation for earlier periods in Antarctica, but in Greenland the relation may have varied with time. When determining past climates from the isotopic record, allowances have to be made for changes in the flow and thickness of ice sheets during major glacial periods. These factors are considered in relation to major ice cores from Vostok and Byrd stations in Antarctica and from Camp Century in Greenland. Vostok is the simplest case glaciologically, Camp Century the most complex. On purely glaciological grounds it appears that the ice age gave way to present-day climates some 10 000 ± 1000 a B.P., the coldest period being 20 000 + 3000 a B.P., when the climate in Antarctica was 6-8 °C colder than at present. Glaciological data suggest a duration of 50 000 to 100 000 years for the last ice age. Before this period, climates in Greenland and Antarctica appear to have been around 2-3 °C warmer than at present.

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A Detailed Analysis of the Rapid Changes in Ice-Core Parameters During the last Ice Age

Annals of Glaciology ◽

10.3189/s0260305500004377 ◽

1988 ◽

Vol 10 ◽

pp. 167-170 ◽

Cited By ~ 2

Author(s):

T. Staffelbach ◽

B. Stauffer ◽

H. Oeschger

Keyword(s):

Molecular Diffusion ◽

Ice Core ◽

Ice Cores ◽

Ice Age ◽

Small Scale ◽

Last Glaciation ◽

Rapid Changes ◽

Last Ice Age ◽

Most Probable Explanation ◽

Equal Density

Results from deep Greenland ice cores show rapid changes in several parameters in the deepest part. The most probable explanation for these variations is a fast-changing climate during part of the last glaciation. The question arises, however, of whether the observed changes in the ice cores could also be due to, or at least be influenced by, discontinuities in the stratigraphy. We present new CO2 and δ18O data from the Camp Century and Dye 3 deep ice cores. The data show rapid changes in CO2 and δ18O in both cores. One transition which was investigated in detail seems to be more rapid in the ice core from Dye 3 than in the Camp Century core. The broadening of a sharp δ18O transition due to molecular diffusion is discussed. Since this broadening is larger than the observed width of the transition, we discuss the possibility of a mechanism that can produce stratigraphic disturbances on a small scale. This mechanism is based on a calculation of the compression of horizontal layers which have equal density but different viscosities.

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Zur Entstehung des Talkessels von La Paz/Bolivien und Umgebung

Geographica Helvetica ◽

10.5194/gh-34-43-1979 ◽

1979 ◽

Vol 34 (1) ◽

pp. 43-49 ◽

Cited By ~ 3

Author(s):

C. Villarroel ◽

K. Graf

Keyword(s):

Ice Age ◽

Interglacial Period ◽

Mountain Range ◽

Last Interglacial ◽

La Paz ◽

Late Pliocene ◽

Last Interglacial Period ◽

Last Ice Age ◽

Landscape Units ◽

The Town

Abstract. The town of La Paz is situated between the Bolivian Highland (Altiplano) and the Central Mountain Range. These two landscape units were mostly formed during the Tertiary. But at their intermediate bordering zone, geomorphological forms have 'later been reshaped. At the end of the Pliocene, a peneplain was formed (the Altiplano of today) and got covered by volcanic ashes. Since the fossilization of mammals (Posnanskytherium) in the late Pliocene, a tektonical uplift of about 3300 ft. has taken place, and huge moraines built up covering the whole city area of today. The enormous La Paz Valley was eroded above all during the last interglacial period. During the last ice age, the glaciers reached the present upper city border only and melted away very rapidly 9800 years ago at the latest.

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Antarctic Winds: Pacemaker of Global Warming, Global Cooling, and the Collapse of Civilizations

Climate ◽

10.3390/cli8110130 ◽

2020 ◽

Vol 8 (11) ◽

pp. 130

Author(s):

W. Davis ◽

W. Davis

Keyword(s):

Global Warming ◽

Little Ice Age ◽

Ice Cores ◽

Ice Age ◽

Temperature Cycle ◽

Wind Pattern ◽

The Past ◽

Global Cooling ◽

Wind Cycle ◽

The Antarctic

We report a natural wind cycle, the Antarctic Centennial Wind Oscillation (ACWO), whose properties explain milestones of climate and human civilization, including contemporary global warming. We explored the wind/temperature relationship in Antarctica over the past 226 millennia using dust flux in ice cores from the European Project for Ice Coring in Antarctica (EPICA) Dome C (EDC) drill site as a wind proxy and stable isotopes of hydrogen and oxygen in ice cores from EDC and ten additional Antarctic drill sites as temperature proxies. The ACWO wind cycle is coupled 1:1 with the temperature cycle of the Antarctic Centennial Oscillation (ACO), the paleoclimate precursor of the contemporary Antarctic Oscillation (AAO), at all eleven drill sites over all time periods evaluated. Such tight coupling suggests that ACWO wind cycles force ACO/AAO temperature cycles. The ACWO is modulated in phase with the millennial-scale Antarctic Isotope Maximum (AIM) temperature cycle. Each AIM cycle encompasses several ACWOs that increase in frequency and amplitude to a Wind Terminus, the last and largest ACWO of every AIM cycle. This historic wind pattern, and the heat and gas exchange it forces with the Southern Ocean (SO), explains climate milestones including the Medieval Warm Period and the Little Ice Age. Contemporary global warming is explained by venting of heat and carbon dioxide from the SO forced by the maximal winds of the current positive phase of the ACO/AAO cycle. The largest 20 human civilizations of the past four millennia collapsed during or near the Little Ice Age or its earlier recurrent homologs. The Eddy Cycle of sunspot activity oscillates in phase with the AIM temperature cycle and therefore may force the internal climate cycles documented here. Climate forecasts based on the historic ACWO wind pattern project imminent global cooling and in ~4 centuries a recurrent homolog of the Little Ice Age. Our study provides a theoretically-unified explanation of contemporary global warming and other climate milestones based on natural climate cycles driven by the Sun, confirms a dominant role for climate in shaping human history, invites reconsideration of climate policy, and offers a method to project future climate.

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10Be Concentrations in Antarctic Ice

Annals of Glaciology ◽

10.1017/s0260305500004456 ◽

1988 ◽

Vol 10 ◽

pp. 200

Author(s):

J. Beer ◽

H. Oeschger ◽

G. Bonani ◽

M. Suter ◽

W. Wölfli

Keyword(s):

Production Rate ◽

Atmospheric Circulation ◽

Ice Cores ◽

Ice Age ◽

Solar Modulation ◽

Short Term ◽

Cosmogenic Isotope ◽

Last Ice Age ◽

Low Precipitation ◽

Good Agreement

Measurements of the cosmogenic isotope 10Be (T½ = 1.5 Ma) on Greenland ice cores produced interesting results. Variations in the 10Be concentrations can be interpreted in terms of changes in the production rate and in atmospheric circulation and deposition. During the Holocene, good agreement between short-term variations in 10Be and 14C indicates that the production rate of both isotopes was changing, probably due to solar modulation. During the last ice age, periods with significantly higher 10Be concentrations are observed. The good anti-correlation between 10Be and δ18O suggests that these intervals correspond to periods of low precipitation rates. Work on Antarctic ice cores is in progress, but only relatively few 10Be data have been published yet. 10 Be results from Antarctic ice cores are presented and compared with data from Greenland.

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