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

2009 ◽  
Vol 5 (1) ◽  
pp. 53-72 ◽  
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.

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

2008 ◽  
Vol 4 (2) ◽  
pp. 375-414 ◽  
Author(s):  
S. Desprat ◽  
M. F. Sánchez Goñi ◽  
J. Duprat ◽  
E. Cortijo ◽  
J. F. McManus
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 characterised by particular baseline climate states. This study enables to document the vegetation changes in 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 appears 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 appears related to changes in deep water circulation and likely to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of a 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.

The complexity of millennial-scale variability in southwestern Europe during MIS 11

2016 ◽  
Vol 86 (3) ◽  
pp. 373-387 ◽  
Author(s):  
Dulce Oliveira ◽  
Stephanie Desprat ◽  
Teresa Rodrigues ◽  
Filipa Naughton ◽  
David Hodell ◽  
...  
Keyword(s):  
Climatic Variability ◽  
Oscillation Mode ◽  
Hydrological Regime ◽  
Meridional Overturning Circulation ◽  
Ice Volume ◽  
Sst Variability ◽  
Prolonged Duration ◽  
Meridional Overturning ◽  
Baseline Climate ◽  
Millennial Scale

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.

scholarly journals Climate and vegetation changes during the Lateglacial and early–middle Holocene at Lake Ledro (southern Alps, Italy)

2013 ◽  
Vol 9 (2) ◽  
pp. 913-933 ◽  
Author(s):  
S. Joannin ◽  
B. Vannière ◽  
D. Galop ◽  
O. Peyron ◽  
J. N. Haas ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Transition Period ◽  
Southern Alps ◽  
Dominant Factor ◽  
Vegetation Changes ◽  
Pollen Record ◽  
Lake Levels ◽  
Cold Event ◽  
Middle Holocene ◽  
Erosion Processes

Abstract. Adding to the on-going debate regarding vegetation recolonisation (more particularly the timing) in Europe and climate change since the Lateglacial, this study investigates a long sediment core (LL081) from Lake Ledro (652 m a.s.l., southern Alps, Italy). Environmental changes were reconstructed using multiproxy analysis (pollen-based vegetation and climate reconstruction, lake levels, magnetic susceptibility and X-ray fluorescence (XRF) measurements) recorded climate and land-use changes during the Lateglacial and early–middle Holocene. The well-dated and high-resolution pollen record of Lake Ledro is compared with vegetation records from the southern and northern Alps to trace the history of tree species distribution. An altitude-dependent progressive time delay of the first continuous occurrence of Abies (fir) and of the Larix (larch) development has been observed since the Lateglacial in the southern Alps. This pattern suggests that the mid-altitude Lake Ledro area was not a refuge and that trees originated from lowlands or hilly areas (e.g. Euganean Hills) in northern Italy. Preboreal oscillations (ca. 11 000 cal BP), Boreal oscillations (ca. 10 200, 9300 cal BP) and the 8.2 kyr cold event suggest a centennial-scale climate forcing in the studied area. Picea (spruce) expansion occurred preferentially around 10 200 and 8200 cal BP in the south-eastern Alps, and therefore reflects the long-lasting cumulative effects of successive boreal and the 8.2 kyr cold event. The extension of Abies is contemporaneous with the 8.2 kyr event, but its development in the southern Alps benefits from the wettest interval 8200–7300 cal BP evidenced in high lake levels, flood activity and pollen-based climate reconstructions. Since ca. 7500 cal BP, a weak signal of pollen-based anthropogenic activities suggest weak human impact. The period between ca. 5700 and ca. 4100 cal BP is considered as a transition period to colder and wetter conditions (particularly during summers) that favoured a dense beech (Fagus) forest development which in return caused a distinctive yew (Taxus) decline. We conclude that climate was the dominant factor controlling vegetation changes and erosion processes during the early and middle Holocene (up to ca. 4100 cal BP).

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

2018 ◽  
Vol 14 (10) ◽  
pp. 1361-1375 ◽  
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.

Holocene annual mean temperature changes in Estonia and their relationship to solar insolation and atmospheric circulation patterns

2004 ◽  
Vol 61 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Heikki Seppä ◽  
Anneli Poska
Keyword(s):  
North Atlantic ◽  
Climatic Variability ◽  
Weighted Averaging ◽  
Coefficient Of Determination ◽  
Calibration Model ◽  
Cold Event ◽  
The North ◽  
Mean Temperature ◽  
Decadal Scale ◽  
The North Atlantic

We reconstructed annual mean temperature (Tann) trends from three radiocarbon-dated Holocene pollen stratigraphies from lake sediments in Estonia, northern Europe. The reconstructions were carried out using a North-European pollen-climate calibration model based on weighted averaging partial least-squares regression. The cross-validated prediction error of the model is 0.89°C and the coefficient of determination between observed modern Tann values and those predicted by the model is 0.88. In the reconstruction, the Holocene thermal maximum (HTM) is distinguishable at 8000–4500 cal yr B.P. with the expansion of thermophilous tree species and Tann on average 2.5°C higher than at present. The pollen-stratigraphical data reflect progressively warmer and drier summers during the HTM. Analogously with the modern decadal-scale climatic variability in North Europe, we interpret this as an indication of increasing climatic continentality due to the intensification of anticyclonic circulation and meridional air flow. Post-HTM cooling started abruptly at around 4500 cal yr B.P. All three reconstructions show a transient (ca. 300 years) cooling of 1.5–2.0°C at 8600–8000 cal yr B.P. We tentatively correlate this cold event with the North-Atlantic “8.2 ka event” at 8400–8000 cal yr B.P. Provided that the 8.2 ka event was caused by freshening of the North-Atlantic surface water, our data provide evidence of the climatic and vegetational responsiveness of the boundary of the temperate and boreal zones to the weakening of the North-Atlantic thermohaline circulation and the zonal energy transport over Europe. No other cold events of comparable magnitude are indicated during the last 8000 years.

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

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

<p>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 <em>Cedrus</em> pollen abundances, which most-likely originated from Northern Africa and were carried to Sierra Nevada by wind. Although <em>Cedrus</em> 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 <em>Cedrus</em> 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 <em>Cedrus</em> synthetic record. <em>Cedrus</em> abundance oscillations could have been produced by well-known millennial-scale climatic variability that controlled cedar abundance in montane areas of N Africa.  </p>

scholarly journals Climate and vegetation changes during the Lateglacial and Early-Mid Holocene at Lake Ledro (southern Alps, Italy)

2012 ◽  
Vol 8 (6) ◽  
pp. 5583-5632 ◽  
Author(s):  
S. Joannin ◽  
B. Vannière ◽  
D. Galop ◽  
O. Peyron ◽  
J.-N. Haas ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Transition Period ◽  
Anthropogenic Activities ◽  
Southern Alps ◽  
Dominant Factor ◽  
Vegetation Changes ◽  
Pollen Record ◽  
Lake Levels ◽  
Cold Event ◽  
Erosion Processes

Abstract. Adding to the on-going debate regarding vegetation recolonisation in Europe and climate change since the Lateglacial, this study investigates a long sediment core (LL081) from Lake Ledro (652 m a.s.l., southern Alps, Italy). Environmental changes that where reconstructed using multiproxy analysis (pollen-based vegetation and climate reconstruction, lake-levels, magnetic susceptibility and X-ray fluorescence (XRF) measurements) recorded climate and land-use changes during the Lateglacial and Early-Mid Holocene. The well-dated and high-resolution pollen record of Lake Ledro is compared with vegetation records from the southern and northern Alps to trace the history of distribution tree species. An altitude-dependent progressive time-delay of the first continuous occurrence of Abies (fir) and of the Larix (larch) development has been observed since the Lateglacial in the southern Alps. This pattern suggests that the mid-altitude Lake Ledro area was not a refuge and that trees originated from lowlands or hilly areas (e.g. Euganean Hills) in northern Italy. Preboreal oscillations (ca. 11 000 cal. BP), Boreal oscillations (ca. 10 200, 9300 cal. BP) and n.e. 8.2 kyr cold event suggest a centennial-scale short-lasting climate forcing in the studied area. Picea (spruce) expansion occurred preferentially around 10 200 cal. BP and 8200 cal. BP in the south-eastern Alps and, therefore, reflects the long-lasting cumulative effects of successive boreal and 8.2 kyr cold events. The extension of Abies is contemporaneous with the 8.2 kyr event, but its development in the southern Alps benefits from the wettest interval 8200–7300 cal. BP evidenced in high lake-levels, flood activity and pollen-based climate reconstructions. Since ca. 7500 cal. BP, low signal of pollen-based anthropogenic activities suggest a weak human impact. The period between ca. 5700 and ca. 4100 cal. BP is considered as a transition period to colder and wetter conditions (particularly during summers) that favoured a dense beech (Fagus) forest development which in return caused a distinctive yew (Taxus) decline. We conclude that climate was the dominant factor controlling vegetation changes and erosion processes during the Early and Mid Holocene (up to ca. 4100 cal. BP).

Climatic Change on the Iberian Peninsula Recorded in a 30,000-Yr Pollen Record from Lake Banyoles

1994 ◽  
Vol 41 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Ramon Pèrez-Obiol ◽  
Ramon Julià
Keyword(s):  
Iberian Peninsula ◽  
Younger Dryas ◽  
Late Glacial ◽  
Pollen Record ◽  
Cold Event ◽  
Pollen Diagram ◽  
Climatic Oscillations ◽  
The North ◽  
History Of ◽  
Younger Dryas Event

AbstractThe Banyoles lacustrine sequence shows that the vegetational history of the northeastern Iberian Peninsula during the last 30,000 yr follows the North Atlantic pattern of climatic oscillations. The Banyoles pollen diagram, supported by two calibrated 14C dates and nine U/Th dates, shows a clear interstadial event between 30,000 and 27,000 yr B.P., a Pleniglacial period with minor oscillations that ended abruptly ca. 14,420 ± 410 yr B.P., and a late-glacial sequence that records the classical stages described in Northern Europe: the Bølling-Allerød Interstade, the Younger Dryas event at 12,000 yr B.P. (U-series age), and a short warming phase between the Younger Dryas and the last cold event (dated at 11,000 yr B.P., U-series age).

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