Neandertal extinction and the millennial scale climatic variability of OIS 3

AbstractClimatic variability of Marine Isotope Stage (MIS) 11 is examined using a new high-resolution direct land—sea comparison from the SW Iberian margin Site U1385. This study, based on pollen and biomarker analyses, documents regional vegetation, terrestrial climate and sea surface temperature (SST) variability. Suborbital climate variability is revealed by a series of forest decline events suggesting repeated cooling and drying episodes in SW Iberia throughout MIS 11. Only the most severe events on land are coeval with SST decreases, under larger ice volume conditions. Our study shows that the diverse expression (magnitude, character and duration) of the millennial-scale cooling events in SW Europe relies on atmospheric and oceanic processes whose predominant role likely depends on baseline climate states. Repeated atmospheric shifts recalling the positive North Atlantic Oscillation mode, inducing dryness in SW Iberia without systematical SST changes, would prevail during low ice volume conditions. In contrast, disruption of the Atlantic meridional overturning circulation (AMOC), related to iceberg discharges, colder SST and increased hydrological regime, would be responsible for the coldest and driest episodes of prolonged duration in SW Europe.

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Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period

Climate of the Past Discussions ◽

10.5194/cpd-6-135-2010 ◽

2010 ◽

Vol 6 (1) ◽

pp. 135-183 ◽

Cited By ~ 6

Author(s):

E. Capron ◽

A. Landais ◽

J. Chappellaz ◽

A. Schilt ◽

D. Buiron ◽

...

Keyword(s):

Climatic Variability ◽

Ice Sheets ◽

Ice Cores ◽

Glacial Period ◽

Last Glacial Period ◽

Last Glacial ◽

Dronning Maud Land ◽

Mis 5 ◽

The Last Glacial ◽

Millennial Scale

Abstract. Since its discovery in Greenland ice cores, the millennial scale climatic variability of the last glacial period has been increasingly documented at all latitudes with studies focusing mainly on Marine Isotopic Stage 3 (MIS 3; 28–60 thousand of years before present, hereafter ka) and characterized by short Dansgaard-Oeschger (DO) events. Recent and new results obtained on the EPICA and NorthGRIP ice cores now precisely describe the rapid variations of Antarctic and Greenland temperature during MIS 5 (73.5–123 ka), a time period corresponding to relatively high sea level. The results display a succession of long DO events enabling us to highlight a sub-millennial scale climatic variability depicted by i) short-lived and abrupt warming events preceding some Greenland InterStadial (GIS) (precursor-type events) and ii) abrupt warming events at the end of some GIS (rebound-type events). The occurrence of these secondary events is suggested to be driven by the Northern Hemisphere summertime insolation at 65° N together with the internal forcing of ice sheets. Thanks to a recent NorthGRIP-EPICA Dronning Maud Land (EDML) common timescale over MIS 5, the bipolar sequence of climatic events can be established at millennial to sub-millennial timescale. This provides evidence that a linear relationship is not satisfactory in explaining the link between Antarctic warming amplitudes and the duration of their concurrent Greenland Stadial (GS) for the entire glacial period. The conceptual model for a thermal bipolar seesaw permits a reconstruction of the Antarctic response to the northern millennial and sub-millennial scale variability over MIS 5. However, we show that when ice sheets are extensive, Antarctica does not necessarily warm during the whole GS as the thermal bipolar seesaw model would predict.

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Last interglacial ocean changes in the Bahamas: climate teleconnections between low and high latitudes

Climate of the Past ◽

10.5194/cp-14-1361-2018 ◽

2018 ◽

Vol 14 (10) ◽

pp. 1361-1375 ◽

Cited By ~ 1

Author(s):

Anastasia Zhuravleva ◽

Henning A. Bauch

Keyword(s):

Climatic Variability ◽

Meridional Overturning Circulation ◽

Interglacial Period ◽

Subtropical Climate ◽

High Latitudes ◽

Last Interglacial ◽

The Bahamas ◽

Foraminiferal Assemblage ◽

Mis 5E ◽

Millennial Scale

Abstract. Paleorecords and modeling studies suggest that instabilities in the Atlantic Meridional Overturning Circulation (AMOC) strongly affect the low-latitude climate, namely via feedbacks on the Atlantic Intertropical Convergence Zone (ITCZ). Despite the pronounced millennial-scale overturning and climatic variability documented in the subpolar North Atlantic during the last interglacial period (MIS 5e), studies on cross-latitudinal teleconnections remain very limited. This precludes a full understanding of the mechanisms controlling subtropical climate evolution across the last warm cycle. Here, we present new planktic foraminiferal assemblage data combined with δ18O values in surface and thermocline-dwelling foraminifera from the Bahamas, a region ideally suited to studying past changes in the subtropical ocean and atmosphere. Our data reveal that the peak sea surface warmth during early MIS 5e was intersected by an abrupt millennial-scale cooling/salinification event, which was possibly associated with a sudden southward displacement of the mean annual ITCZ position. This atmospheric shift is, in turn, ascribed to the transitional climatic regime of early MIS 5e, which was characterized by persistent ocean freshening in the high latitudes and an unstable AMOC mode.

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Millennial-scale climatic variability between 340 000 and 270 000 years ago in SW Europe: evidence from a NW Iberian margin pollen sequence

Climate of the Past ◽

10.5194/cp-5-53-2009 ◽

2009 ◽

Vol 5 (1) ◽

pp. 53-72 ◽

Cited By ~ 35

Author(s):

S. Desprat ◽

M. F. Sánchez Goñi ◽

J. F. McManus ◽

J. Duprat ◽

E. Cortijo

Keyword(s):

Climatic Variability ◽

Interglacial Period ◽

Vegetation Changes ◽

Pollen Record ◽

Cold Event ◽

Ice Volume ◽

The North ◽

Nw Iberia ◽

Iberian Margin ◽

Millennial Scale

Abstract. We present a new high-resolution marine pollen record from NW Iberian margin sediments (core MD03-2697) covering the interval between 340 000 and 270 000 years ago, a time period centred on Marine Isotope Stage (MIS) 9 and characterized by particular baseline climate states. This study enables the documentation of vegetation changes in the north-western Iberian Peninsula and therefore the terrestrial climatic variability at orbital and in particular at millennial scales during MIS 9, directly on a marine stratigraphy. Suborbital vegetation changes in NW Iberia in response to cool/cold events are detected throughout the studied interval even during MIS 9e ice volume minimum. However, they appear more frequent and of higher amplitude during the 30 000 years following the MIS 9e interglacial period and during the MIS 9a-8 transition, which correspond to intervals of an intermediate to high ice volume and mainly periods of ice growth. Each suborbital cold event detected in NW Iberia has a counterpart in the Southern Iberian margin SST record. High to moderate amplitude cold episodes detected on land and in the ocean appear to be related to changes in deep water circulation and probably to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of pervasive millennial-scale climatic variability in the North Atlantic borderlands throughout past climatic cycles of the Late Pleistocene, regardless of glacial state. However, ice volume might have an indirect influence on the amplitude of the millennial climatic changes in Southern Europe.

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Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period

Climate of the Past ◽

10.5194/cp-6-345-2010 ◽

2010 ◽

Vol 6 (3) ◽

pp. 345-365 ◽

Cited By ~ 113

Author(s):

E. Capron ◽

A. Landais ◽

J. Chappellaz ◽

A. Schilt ◽

D. Buiron ◽

...

Keyword(s):

Climatic Variability ◽

Ice Core ◽

Ice Sheets ◽

Ice Cores ◽

Glacial Period ◽

Last Glacial Period ◽

Last Glacial ◽

Mis 5 ◽

The Last Glacial ◽

Millennial Scale

Abstract. Since its discovery in Greenland ice cores, the millennial scale climatic variability of the last glacial period has been increasingly documented at all latitudes with studies focusing mainly on Marine Isotopic Stage 3 (MIS 3; 28–60 thousand of years before present, hereafter ka) and characterized by short Dansgaard-Oeschger (DO) events. Recent and new results obtained on the EPICA and NorthGRIP ice cores now precisely describe the rapid variations of Antarctic and Greenland temperature during MIS 5 (73.5–123 ka), a time period corresponding to relatively high sea level. The results display a succession of abrupt events associated with long Greenland InterStadial phases (GIS) enabling us to highlight a sub-millennial scale climatic variability depicted by (i) short-lived and abrupt warming events preceding some GIS (precursor-type events) and (ii) abrupt warming events at the end of some GIS (rebound-type events). The occurrence of these sub-millennial scale events is suggested to be driven by the insolation at high northern latitudes together with the internal forcing of ice sheets. Thanks to a recent NorthGRIP-EPICA Dronning Maud Land (EDML) common timescale over MIS 5, the bipolar sequence of climatic events can be established at millennial to sub-millennial timescale. This shows that for extraordinary long stadial durations the accompanying Antarctic warming amplitude cannot be described by a simple linear relationship between the two as expected from the bipolar seesaw concept. We also show that when ice sheets are extensive, Antarctica does not necessarily warm during the whole GS as the thermal bipolar seesaw model would predict, questioning the Greenland ice core temperature records as a proxy for AMOC changes throughout the glacial period.

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A window into mid-latitudinal Early Eocene environmental variability: a high-resolution palynological analysis of the Falkland site, Okanagan Highlands, British Columbia, Canada

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2015-0167 ◽

2016 ◽

Vol 53 (6) ◽

pp. 605-613 ◽

Cited By ~ 6

Author(s):

Patrick T. Moss ◽

Robin Y. Smith ◽

David R. Greenwood

Keyword(s):

British Columbia ◽

High Resolution ◽

Vegetation Change ◽

Volcanic Ash ◽

Environmental Variability ◽

Climatic Variability ◽

Volcanic Eruptions ◽

Early Eocene ◽

Okanagan Highlands ◽

Millennial Scale

A series of Eocene lake shale deposits from British Columbia, coined the Okanagan Highlands, are dated from associated volcanic ash as mostly from the Early Eocene Climatic Optimum (EECO), the longest persisting of the early Paleogene hyperthermals. In this report we focus on high-resolution palynological sampling of short sequences for the Falkland site to determine if they record centennial- or millennial-scale vegetation change during the EECO. The Falkland shales consist of alternating dark- and light-coloured irregular laminae, along with interleaved tephras from volcanic eruptions. At this site it is apparent that deposition occurred over several millennia. Pollen grains were counted under light microscopy using a standard transect method, with clustering analysis determining whether the data show any long-term trends in plant representation and abundance. Our data show that regional vegetation was impacted by millennial- to centennial-scale climatic variability, as well as the effects of volcanic eruptions. At Falkland there appears to be alterations in vegetation assemblages (birch – golden larch association to fir–spruce) that reflect longer-term (centennial to millennial) climatic transitions (warm/wet to cool/dry). Within this sequence, a period of environmental disturbance (reflected in the presence of multiple volcanic ash layers, wave ripple marks, and a fish-kill layer) has a marked impact on vegetation representation, with a dramatic increase in Abies and Picea pollen at the expense of Alnus and Betula, which do eventually recover. These results suggest mid-latitude millennial-scale climate oscillations in the waning period of the EECO of a similar magnitude to Holocene variability.

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The Holocene Cedrus pollen record from Sierra Nevada (S Spain), a proxy for climate change in N Africa

10.5194/egusphere-egu2020-14958 ◽

2020 ◽

Author(s):

Gonzalo Jiménez-Moreno ◽

R. Scott Anderson ◽

María J. Ramos-Román ◽

Jon Camuera ◽

Jose Manuel Mesa-Fernández ◽

...

Keyword(s):

Sierra Nevada ◽

Climatic Variability ◽

Mediterranean Area ◽

Western Mediterranean ◽

Northern Africa ◽

Pollen Record ◽

North African ◽

The Holocene ◽

Middle And Late Holocene ◽

Millennial Scale

In this study, we synthesized pollen data from seven sites from the Sierra Nevada in southern Spain to investigate the response of forests in the western Mediterranean area to centennial- and millennial-scale climate changes and to human impact during the Holocene. In particular, here we focused in Cedrus pollen abundances, which most-likely originated from Northern Africa and were carried to Sierra Nevada by wind. Although Cedrus abundances are generally lower than 1% in the studied pollen samples, a comparison with North African pollen records shows similar trends at long- and short-term time-scales. Therefore, this record could be used as a proxy for changes in this forest species in North Africa. A Middle and Late Holocene Cedrus pollen increasing trend has been observed in the Sierra Nevada synthetic record, which seems to be the result of decreasing summer insolation. This would have produced overall cooler annual temperatures in Northern Africa (Atlas and Rif Mountains), benefiting the growth of this cool-adapted montane tree species, and lower summer evaporation, increasing available moisture during the summer, which is critical for this water-demanding species. Millennial- and centennial-scale variability also characterize the Sierra Nevada Cedrus synthetic record. Cedrus abundance oscillations could have been produced by well-known millennial-scale climatic variability that controlled cedar abundance in montane areas of N Africa.&#160;&#160;

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