scholarly journals Climate variability in the Spanish Pyrenees during the last 30,000 yr revealed by the El Portalet sequence

2006 ◽  
Vol 66 (1) ◽  
pp. 38-52 ◽  
Author(s):  
P. González-Sampériz ◽  
B.L. Valero-Garcés ◽  
A. Moreno ◽  
G. Jalut ◽  
J.M. García-Ruiz ◽  
...  
Keyword(s):  
High Resolution ◽  
Climate Variability ◽  
Climate Changes ◽  
Vegetation History ◽  
Ice Cores ◽  
Late Glacial ◽  
Last Glacial ◽  
The North ◽  
Isotopic Analyses ◽  
Spanish Pyrenees

AbstractPalynological, sedimentological and stable isotopic analyses of carbonates and organic matter performed on the El Portalet sequence (1802 m a.s.l., 42°48′00ʺN, 0°23′52ʺW) reflect the paleoclimatic evolution and vegetation history in the central-western Spanish Pyrenees over the last 30,000 yr, and provide a high-resolution record for the late glacial period. Our results confirm previous observations that deglaciation occurred earlier in the Pyrenees than in northern European and Alpine sites and point to a glacial readvance from 22,500 to 18,000 cal yr BP, coinciding with the global last glacial maximum. The patterns shown by the new, high-resolution pollen data from this continental sequence, chronologically constrained by 13 AMS 14C dates, seem to correlate with the rapid climate changes recorded in Greenland ice cores during the last glacial–interglacial transition. Abrupt events observed in northern latitudes (Heinrich events 3 to 1, Oldest and Older Dryas stades, Intra-Allerød Cold Period, and 8200 cal yr BP event) were also identified for the first time in a lacustrine sequence from the central-western Pyrenees as cold and arid periods. The coherent response of the vegetation and the lake system to abrupt climate changes implies an efficient translation of climate variability from the North Atlantic to mid latitudes.

scholarly journals Centennial to millennial climate variability in the far northwestern Pacific (off Kamchatka) and its linkage to the East Asian monsoon and North Atlantic from the Last Glacial Maximum to the early Holocene

2017 ◽  
Vol 13 (8) ◽  
pp. 1063-1080 ◽  
Author(s):  
Sergey A. Gorbarenko ◽  
Xuefa Shi ◽  
Galina Yu. Malakhova ◽  
Aleksandr A. Bosin ◽  
Jianjun Zou ◽  
...  
Keyword(s):  
High Resolution ◽  
Climate Variability ◽  
Last Glacial Maximum ◽  
North Atlantic ◽  
Climate Changes ◽  
East Asian ◽  
Early Holocene ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. High-resolution reconstructions based on productivity proxies and magnetic properties of core LV63-41-2 (off Kamchatka) reveal prevailing centennial productivity/climate variability in the northwestern (NW) Pacific from the Last Glacial Maximum (LGM) to the early Holocene (EH). The age model of the core is established by AMS 14C dating and by projections of AMS 14C data of the nearby core SO-201-12KL through correlation of the productivity proxies and relative paleomagnetic intensity. The resulting sequence of centennial productivity increases/climate warming events in the NW Pacific occurred synchronously with the East Asian summer monsoon (EASM) sub-interstadials during the LGM (four events), Heinrich Event 1 (HE1) (four events), Bølling–Allerød (B/A) warming (four events), and over the EH (four events). Remarkable similarity of the sequence of the NW Pacific increased-productivity events with the EASM sub-interstadials over the LGM-HE1 implies that the Siberian High is a strong and common driver. The comparison with the δ18O record from Antarctica suggests that another mechanism associated with the temperature gradient in the Southern Hemisphere may also be responsible for the EASM/NW Pacific centennial events over the LGM-HE1. During the B/A warming and resumption of the Atlantic Meridional Overturning Circulation (AMOC), clear synchronicity between the NW Pacific, EASM and Greenland sub-interstadials was mainly controlled by changes in the atmospheric circulation. During the EH the linkages between solar forcing, ocean circulation, and climate changes likely control the synchronicity of abrupt climate changes in the NW Pacific and North Atlantic. The sequence of centennial events recorded in this study is a persistent regional feature during the LGM-EH, which may serve as a template in high-resolution paleoceanography and sediment stratigraphy in the NW Pacific.

Decoupling of surface ocean hydrology and Greenland ice core records in the eastern North Atlantic during the last glacial inception 

2021 ◽  
Author(s):  
Svetlana Radionovskaya ◽  
Luke Skinner ◽  
Mervyn Greaves
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
Benthic Foraminifera ◽  
Ice Cores ◽  
Last Glacial ◽  
Surface Ocean ◽  
The North ◽  
The North Atlantic ◽  
Iberian Margin ◽  
The Last Glacial

<p>MIS 4, a key paleoclimatic interval for the last glacial inception, is characterized by a rapid CO<sub>2</sub> drop of approx. ~28ppm and a large drop in temperature (as seen in Antarctic ice cores). SSTs in the North Atlantic are thought to be coupled to AMOC strength, whereby various proxies suggest a weaker and shoaled AMOC during the transition from MIS5a to MIS4. Furthermore, several millennial events also occurred during MIS 4, including Heinrich Stadial 6 and DO events 16-19. MIS 4 is thus an ideal interval to study and eventually to disentangle, glacial-interglacial and millennial variability.</p><p>Here, we present high resolution planktonic and benthic foraminifera geochemical data from several marine sediment cores from the Iberian Margin (including stable isotope and trace element data). The Iberian Margin is a prime location to study millennial-scale climate variability as isotope records of planktonic and benthic foraminifera simultaneously recorded rapid climate change expressed in Greenland and Antarctic ice cores, respectively, during the last glacial period. However, our results so far, suggest that surface ocean response at this site does not track Greenland temperature, as would be expected for this region of the North Atlantic. Perhaps the most striking, our planktic Mg/Ca record shows a late onset of rapid MIS 4 cooling at the start of Heinrich 6, and no clear millennial variability signal. This is in agreement with SST reconstructed using alkenones (Pailler and Bard, 2002) and planktonic foraminifera faunal assemblages (Salgueiro et al., 2010) from nearby core sites. Local d18O seawater reconstructions imply major hydrological changes in the region, which is supported by the “dry event” seen in speleothems from North Eastern Iberia (Perez-Mehias et al., 2019) and Italy (Columbu et al., 2020), just before Heinrich 6. We propose that the observed changes may reflect changes in regional ocean and atmospheric circulation patterns such as the interaction of the strength and position of the Azores Current, Iberian Poleward Current and the Subtropical Gyre, which in turn could depend on the larger scale AMOC and wind driven surface ocean changes due to glacial-interglacial and millennial variability. Further links to moisture transport, ice sheet growth and carbon cycle are yet to be investigated.</p><p> </p><p><strong>References</strong></p><p>Columbu, A., Chiarini, V., Spötl, C., Benazzi, S., Hellstrom, J., Cheng, H. and De Waele, J., 2020. Speleothem record attests to stable environmental conditions during Neanderthal–modern human turnover in southern Italy. Nature Ecology & Evolution, 4(9), pp.1188-1195.</p><p>Pailler, D. and Bard, E., 2002. High frequency palaeoceanographic changes during the past 140 000 yr recorded by the organic matter in sediments of the Iberian Margin. Palaeogeography, Palaeoclimatology, Palaeoecology, 181(4), pp.431-452.</p><p>Pérez-Mejías, C., Moreno, A., Sancho, C., Martín-García, R., Spötl, C., Cacho, I., Cheng, H. and Edwards, R., 2019. Orbital-to-millennial scale climate variability during Marine Isotope Stages 5 to 3 in northeast Iberia. Quaternary Science Reviews, 224, p.105946.</p><p>Salgueiro, E., Voelker, A., de Abreu, L., Abrantes, F., Meggers, H. and Wefer, G., 2010. Temperature and productivity changes off the western Iberian margin during the last 150 ky. Quaternary Science Reviews, 29(5-6), pp.680-695.</p>

scholarly journals Eurasian contribution to the last glacial dust cycle: how are loess sequences built?

2017 ◽  
Author(s):  
Denis-Didier Rousseau ◽  
Anders Svensson ◽  
Matthias Bigler ◽  
Adriana Sima ◽  
Jorgen Peder Steffensen ◽  
...  
Keyword(s):  
Climate Variability ◽  
Northern Hemisphere ◽  
Ice Cores ◽  
Critical Study ◽  
Sea Ice Extent ◽  
Chinese Loess ◽  
Middle Latitudes ◽  
The North ◽  
Terrestrial Environments ◽  
Desert Areas

Abstract. The last 130 000 years have been marked by pronounced millennial scale climate variability, which strongly impacted the terrestrial environments of the Northern Hemisphere especially at middle latitudes. Identifying the trigger of these variations, which are most likely associated with strong couplings between the ocean and the atmosphere, still remains a key question. Here, we show that the analysis of δ18O and dust in the Greenland ice cores, and a critical study of their source variations, reconciles these records with those observed on the Eurasian continent. We demonstrate the link between European and Chinese loess sequences, dust records in Greenland, and variations of the North Atlantic sea ice extent. The sources of the emitted and transported dust material are variable and relate to different environments corresponding to present desert areas, but also hidden regions related to lower sea level stands, dry rivers, or zones close to the frontal moraines of the main Northern Hemisphere ice sheets. We anticipate our study to be at the origin of more sophisticated and elaborated investigations of millennial and sub-millennial continental climate variability on the Northern Hemisphere.

scholarly journals NALPS19: Sub-orbital scale climate variability recorded in Northern Alpine speleothems during the last glacial period

2019 ◽  
Author(s):  
Gina E. Moseley ◽  
Christoph Spötl ◽  
Susanne Brandstätter ◽  
Tobias Erhardt ◽  
Marc Luetscher ◽  
...  
Keyword(s):  
Climate Variability ◽  
Asian Monsoon ◽  
Ice Core ◽  
Ice Cores ◽  
High Elevation ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Change State ◽  
The Last Glacial

Abstract. Sub-orbital-scale climate variability of the last glacial period provides important insights into the rates that the climate can change state, the mechanisms that drive that change, and the leads, lags and synchronicity occurring across different climate zones. Such short-term climate variability has previously been investigated using speleothems from the northern rim of the Alps (NALPS), enabling direct chronological comparisons with highly similar shifts in Greenland ice cores. In this study, we present NALPS19, which includes a revision of the last glacial NALPS δ18O chronology over the interval 118.3 to 63.7 ka using eleven,newly-available, clean, precisely-dated stalagmites from five caves. Using only the most reliable and precisely dated records, this period is now 90 % complete and is comprised of 15 stalagmites from seven caves. Where speleothems grew synchronously, major transitional events between stadials and interstadials (and vice versa) are all in agreement within uncertainty. Ramp-fitting analysis further reveals good agreement between the NALPS19 speleothem δ18O record, the GICC05modelext NGRIP ice-core δ18O record, and the Asian Monsoon composite speleothem δ18O record. In contrast, NGRIP ice-core δ18O on AICC2012 appears to be considerably too young. We also propose a longer duration for the interval covering Greenland Stadial (GS) 22 to GS-21.2 in line with the Asian monsoon and NGRIP-EDML. Given the near-complete record of δ18O variability during the last glacial period in the northern Alps, we offer preliminary considerations regarding the controls on mean δ18O. We find that as expected, δ18O values became increasingly more depleted with distance from the oceanic source regions, and increasingly depleted with increasing altitude. Exceptions were found for some high-elevation sites that locally display δ18O values that are too high in comparison to lower-elevation sites, thus indicating a summer bias in the recorded signal. Finally, we propose a new mechanism for the centennial-scale stadial-level depletions in δ18O such as "pre-cursor" events GS-16.2, GS-17.2, GS-21.2, and GS-23.2, as well as the "within-interstadial" GS-24.2 event. Our new high-precision chronology shows that each of these δ18O depletions occurred shortly following rapid rises in sea level associated with increased ice-rafted debris and southward shifts in the Intertropical Convergence Zone, suggesting that influxes of meltwater from moderately-sized ice sheets may have been responsible for the cold reversals causing the AMOC to slow down similar to the Preboreal Oscillation and Older Dryas deglacial events.

scholarly journals High-resolution interpolar difference of atmospheric methane around the Last Glacial Maximum

2012 ◽  
Vol 9 (5) ◽  
pp. 5471-5508 ◽  
Author(s):  
M. Baumgartner ◽  
A. Schilt ◽  
O. Eicher ◽  
J. Schmitt ◽  
J. Schwander ◽  
...  
Keyword(s):  
High Resolution ◽  
Last Glacial Maximum ◽  
Methane Concentration ◽  
Ice Cores ◽  
Glacial Maximum ◽  
Atmospheric Methane ◽  
Before Present ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Reconstructions of past atmospheric methane concentrations are available from ice cores from both, Greenland and Antarctica. The difference observed between the two polar methane concentration levels is a valuable additional parameter which allows to constrain the geographical location of the responsible methane sources. Here we present new high-resolution methane records from the North Greenland Ice Core Project (NGRIP) and the European Project for Ice Coring in Antarctica (EPICA) Dronning Maud Land (EDML) ice cores covering Termination 1, the Last Glacial Maximum, and parts of the last glacial back to 32 000 years before present. Due to the high-resolution records the synchronisation between the ice cores from NGRIP and EDML is considerably improved and the interpolar concentration difference of methane is determined with unprecedented precision and temporal resolution. Relative to the mean methane concentration, we find a rather stable positive interpolar difference throughout the record with its minimum value of 3.7 ± 0.7 % between 21 900–21 200 years before present, which is higher than previously estimated in this interval close to the Last Glacial Maximum. This implies that Northern Hemisphere boreal wetland sources were never completely shut off during the peak glacial. Starting at 21 000 years before present, i.e. severval millenia prior to the transition into the Holocene, the relative interpolar difference becomes even more positive and stays at a fairly stable level of 6.5 ± 0.8 % during Termination 1. We hypothesise that the anti-correlation observed in the monsoon records from the Northern and Southern Hemispheres induces a methane source redistribution within lower latitudes, which could explain parts of the variations in the interpolar difference.

Climate changes in East China since the Late-glacial inferred from high-resolution mountain peat humification records

2009 ◽  
Vol 52 (1) ◽  
pp. 118-131 ◽  
Author(s):  
ChunMei Ma ◽  
Cheng Zhu ◽  
ChaoGui Zheng ◽  
Qian Yin ◽  
ZhiPing Zhao
Keyword(s):  
High Resolution ◽  
Climate Changes ◽  
Late Glacial ◽  
East China

Vegetation history in central Kentucky and Tennessee (USA) during the last glacial and deglacial periods

2012 ◽  
Vol 79 (2) ◽  
pp. 189-198 ◽  
Author(s):  
Yao Liu ◽  
Jennifer J. Andersen ◽  
John W. Williams ◽  
Stephen T. Jackson
Keyword(s):  
Vegetation Dynamics ◽  
Vegetation History ◽  
Deciduous Tree ◽  
Climatic Warming ◽  
Last Glacial ◽  
The North ◽  
Site Density ◽  
Heinrich Event ◽  
Pollen Records ◽  
The Last Glacial

AbstractKnowledge about vegetation dynamics during the last glacial and deglacial periods in southeastern North America is under-constrained owing to low site density and problematic chronologies. New pollen records from two classic sites, Anderson Pond, TN, and Jackson Pond, KY, supported by AMS 14C age models, span 25.2–13.7 ka and 31.0–15.4 ka, respectively. A transition from Pinus dominance to Picea dominance is recorded at Jackson Pond ca. 26.2 ka, ~ coincident with Heinrich Event H2. Anderson and Jackson Ponds record a transition from conifer to deciduous-tree dominance ~ 15.9 and 15.4 ka, respectively, marking the development of no-analog vegetation characterized by moderate to high abundances of Picea, Quercus, Carya, Ulmus, Fraxinus, Ostrya/Carpinus, Cyperaceae, and Poaceae, and preceding by ~ 2000 yr the advent of similar no-analog vegetation in glaciated terrain to the north. No-analog vegetation developed as a time-transgressive, south-to-north pattern, mediated by climatic warming. Sporormiella abundances are consistently low throughout the Jackson and Anderson Pond records, suggesting that megafaunal abundances and effects on vegetation varied regionally or possibly that the Sporormiella signal was not well-expressed at these sites. Additional records with well-constrained chronologies are necessary to assess patterns and mechanisms of vegetation dynamics during the last glacial and deglacial periods.

scholarly journals Late glacial and Holocene vegetation and regional climate variability evidenced in high-resolution pollen records from Lake Baikal

2005 ◽  
Vol 46 (1-4) ◽  
pp. 255-279 ◽  
Author(s):  
Dieter Demske ◽  
Georg Heumann ◽  
Wojciech Granoszewski ◽  
Małgorzata Nita ◽  
Kazimiera Mamakowa ◽  
...  
Keyword(s):  
High Resolution ◽  
Climate Variability ◽  
Lake Baikal ◽  
Regional Climate ◽  
Late Glacial ◽  
Late Glacial And Holocene ◽  
Pollen Records
Sign in / Sign up

Export Citation Format

Share Document