scholarly journals North Atlantic abrupt climatic events of the Last Glacial period recorded in Ukrainian loess deposits

2010 ◽  
Vol 6 (5) ◽  
pp. 1959-1990
Author(s):  
D.-D. Rousseau ◽  
P. Antoine ◽  
N. Gerasimenko ◽  
A. Sima ◽  
M. Fuchs ◽  
...  
Keyword(s):  
Grain Size ◽  
North Atlantic ◽  
Western Europe ◽  
Climate Modeling ◽  
Ice Cores ◽  
The North ◽  
Recent Climate ◽  
Size Index ◽  
Loess Deposits ◽  
Western European

Abstract. Loess deposits are widely distributed in the Northern Hemisphere, where they have recorded not only the glacial-interglacial cycles, but also millennial-timescale changes resembling those in marine and ice cores. Such abrupt variations are clearly marked in Western European series, but have not yet been evidenced in the east of the continent. Here we present results of the high-resolution investigation of a Weichselian Upper Pleniglacial loess sequence (~38–15 ka) from Stayky, Ukraine. The stratigraphy shows an alternation of loess horizons and embryonic soils, similar to sequences from Western Europe. Similarities are also found between variations of a grain-size index (ratio between coarse and fine material fractions) in Stayky and in Western European profiles. Based on these similarities, and in agreement with the luminescence dates, the embryonic soils are associated to the Greenland interstadials (GIS) 7 to 2, and the Vytachiv paleosol at the base of the sequence, to GIS 8. Pollen analysis indicates a wetter climate for these interstadials, allowing the development of arboreal vegetation, than for the stadials, marked by loess formation. The grain-size index reaches the highest values for intervals correlated with the Heinrich events 3 and 2. Thus, it appears that the North Atlantic abrupt climate changes have extended their influence and modulated the loess sedimentation at least as far as in Eastern Europe. This result is supported by recent climate modeling experiments, and recommends the Stayky sequence as a reference for further comparisons between profiles along the Eurasian loess belt centered at 50° N.

scholarly journals North Atlantic abrupt climatic events of the last glacial period recorded in Ukrainian loess deposits

2011 ◽  
Vol 7 (1) ◽  
pp. 221-234 ◽  
Author(s):  
D.-D. Rousseau ◽  
P. Antoine ◽  
N. Gerasimenko ◽  
A. Sima ◽  
M. Fuchs ◽  
...  
Keyword(s):  
Grain Size ◽  
North Atlantic ◽  
Western Europe ◽  
Climate Modeling ◽  
Ice Cores ◽  
The North ◽  
Recent Climate ◽  
Size Index ◽  
Loess Deposits ◽  
Western European

Abstract. Loess deposits are widely distributed in the Northern Hemisphere, where they have recorded not only the glacial-interglacial cycles, but also millennial-timescale changes resembling those in marine and ice cores. Such abrupt variations are clearly marked in western European series, but have not yet been evidenced in the East of the continent. Here we present results of the high-resolution investigation of a Weichselian Upper Pleniglacial loess sequence (~38–15 ka) from Stayky, Ukraine. The stratigraphy shows an alternation of loess horizons and embryonic soils, similar to sequences from western Europe. Similarities are also found between variations of a grain-size index (ratio between coarse and fine material fractions) in Stayky and in western European profiles. Based on these similarities and in agreement with the luminescence dates, the embryonic soils are associated with the Greenland interstadials (GIS) 7 to 2, and the Vytachiv paleosol at the base of the sequence, with GIS 8. Pollen analysis indicates a wetter climate for these interstadials, allowing the development of arboreal vegetation, than for the stadials, which are marked by loess formation. The grain-size index reaches the highest values for intervals correlated with the Heinrich events 3 and 2. Thus, it appears that the North Atlantic abrupt climate changes have extended their influence and modulated the loess sedimentation at least as far as eastern Europe. This result is supported by recent climate modeling experiments and recommends the Stayky sequence as a reference for further comparisons between profiles along the Eurasian loess belt centered at 50° N.

The Last Piece of the Jigsaw: Britain and the Creation of the Western European Union, 1954

1998 ◽  
Vol 7 (2) ◽  
pp. 181-196 ◽  
Author(s):  
Anne Deighton
Keyword(s):  
European Union ◽  
Cold War ◽  
North Atlantic ◽  
Western Europe ◽  
Political Community ◽  
West Germany ◽  
International Debate ◽  
The North ◽  
Western European ◽  
European Defence Community

By 1955, the formation of a Cold War bloc in Western Europe was complete. The Western European Union (WEU), a redesigned Brussels Treaty Organisation (BTO) within the North Atlantic Treaty Organization (NATO), with West Germany and Italy as members, was created. The 1954 Paris Agreements that established WEU also enabled West Germany to become a virtually sovereign actor, and a member of NATO. The Agreements were effected on the rubble of an acrimonious four-year international debate over a proposed European Defence Community (EDC). This would have created a European army for France, the Benelux countries, Italy and West Germany on the model of the European Coal and Steel Community (ECSC), and a parallel political community for the Six.

scholarly journals The Late Quaternary Sedimentary Record of Reykjanes Ridge, North Atlantic

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 939-947 ◽  
Author(s):  
M A Prins ◽  
S R Troelstra ◽  
R W Kruk ◽  
K van der Borg ◽  
A F M de Jong ◽  
...  
Keyword(s):  
Grain Size ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Late Quaternary ◽  
Ice Cores ◽  
Deep Ocean ◽  
Reykjanes Ridge ◽  
The North ◽  
The North Atlantic ◽  
Deep Ocean Circulation

Variability in surface and deep ocean circulation in the North Atlantic is inferred from grain-size characteristics and the composition of terrigenous sediments from a deep-sea core taken on Reykjanes Ridge, south of Iceland. End-member modeling of grain size data shows that deep-ocean circulation in this area decreased significantly during periods of maximum iceberg discharge. The episodes of reduced circulation correlate with the cold and abrupt warming phases of the Dansgaard-Oeschger cycles as recognized in the Greenland ice cores.

scholarly journals Striking forest revival at the end of the Roman Period in north-western Europe

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
C. Lambert ◽  
A. Penaud ◽  
M. Vidal ◽  
C. Gandini ◽  
L. Labeyrie ◽  
...  
Keyword(s):  
North Atlantic ◽  
Western Europe ◽  
Anthropogenic Activities ◽  
Sedimentary Environment ◽  
Pollen Grains ◽  
Roman Period ◽  
Freshwater Microalgae ◽  
Environmental Signals ◽  
The North ◽  
North Western

AbstractThe Holocene period (last 11,700 years BP) has been marked by significant climate variability over decadal to millennial timescales. The underlying mechanisms are still being debated, despite ocean–atmosphere–land connections put forward in many paleo-studies. Among the main drivers, involving a cluster of spectral signatures and shaping the climate of north-western Europe, are solar activity, the North Atlantic Oscillation (NAO) varying atmospheric regimes and North Atlantic oceanic gyre dynamics. Over the last 2500 years BP, paleo-environmental signals have been strongly affected by anthropogenic activities through deforestation and land use for crops, grazing, habitations, or access to resources. Palynological proxies (especially pollen grains and marine or freshwater microalgae) help to highlight such anthropogenic imprints over natural variability. Palynological analyses conducted in a macro-estuarine sedimentary environment of north-western France over the last 2500 years BP reveal a huge and atypical 300 year-long arboreal increase between 1700 and 1400 years BP (around 250 and 550 years AD) that we refer to as the ‘1.7–1.4 ka Arboreal Pollen rise event’ or ‘1.7–1.4 ka AP event’. Interestingly, the climatic 1700–1200 years BP interval coincides with evidence for the withdrawal of coastal societies in Brittany (NW France), in an unfavourable socio-economic context. We suggest that subpolar North Atlantic gyre strengthening and related increasing recurrence of storminess extremes may have affected long-term coastal anthropogenic trajectories resulting in a local collapse of coastal agrarian societies, partly forced by climatic degradation at the end of the Roman Period.

Correlated Millennial-Scale Changes in Surface Hydrography and Terrigenous Sediment Yield Inferred from Last-Glacial Marine Deposits off Northeastern Brazil

1998 ◽  
Vol 50 (2) ◽  
pp. 157-166 ◽  
Author(s):  
Helge W. Arz ◽  
Jürgen Pätzold ◽  
Gerold Wefer
Keyword(s):  
North Atlantic ◽  
Isotope Composition ◽  
Sediment Cores ◽  
Ice Cores ◽  
Northeastern Brazil ◽  
Salt Flux ◽  
Terrigenous Sediment ◽  
The North ◽  
North Brazil ◽  
The North Atlantic

The stable isotope composition of planktonic foraminifera correlates with evidence for pulses of terrigenous sediment in a sediment core from the upper continental slope off northeastern Brazil. Stable oxygen isotope records of the planktonic foraminiferal species Globigerinoides sacculiferand Globigerinoides ruber(pink) reveal sub-Milankovitch changes in sea-surface hydrography during the last 85,000 yr. Warming of the surface water coincided with terrigenous sedimentation pulses that are inferred from high XRF intensities of Ti and Fe, and which suggest humid conditions in northeast Brazil. These tropical signals correlate with climatic oscillations recorded in Greenland ice cores (Dansgaard-Oeschger cycles) and in sediment cores from the North Atlantic (Heinrich events). Trade winds may have caused changes in the North Brazil Current that altered heat and salt flux into the North Atlantic, thus affecting the growth and decay of the large glacial ice sheets.

North Atlantic jet stream projections in the context of the past 1,250 years

2021 ◽  
Vol 118 (38) ◽  
pp. e2104105118
Author(s):  
Matthew B. Osman ◽  
Sloan Coats ◽  
Sarah B. Das ◽  
Joseph R. McConnell ◽  
Nathan Chellman
Keyword(s):  
21St Century ◽  
North Atlantic ◽  
Climate Model ◽  
Ice Cores ◽  
Natural Variability ◽  
Jet Stream ◽  
Early 21St Century ◽  
The North ◽  
North Atlantic Jet ◽  
Water Isotope

Reconstruction of the North Atlantic jet stream (NAJ) presents a critical, albeit largely unconstrained, paleoclimatic target. Models suggest northward migration and changing variance of the NAJ under 21st-century warming scenarios, but assessing the significance of such projections is hindered by a lack of long-term observations. Here, we incorporate insights from an ensemble of last-millennium water isotope–enabled climate model simulations and a wide array of mean annual water isotope (δ18O) and annually accumulated snowfall records from Greenland ice cores to reconstruct North Atlantic zonal-mean zonal winds back to the 8th century CE. Using this reconstruction we provide preobservational constraints on both annual mean NAJ position and intensity to show that late 20th- and early 21st-century NAJ variations were likely not unique relative to natural variability. Rather, insights from our 1,250 year reconstruction highlight the overwhelming role of natural variability in thus far masking the response of midlatitude atmospheric dynamics to anthropogenic forcing, consistent with recent large-ensemble transient modeling experiments. This masking is not projected to persist under high greenhouse gas emissions scenarios, however, with model projected annual mean NAJ position emerging as distinct from the range of reconstructed natural variability by as early as 2060 CE.

scholarly journals A 60 000 year Greenland stratigraphic ice core chronology

2008 ◽  
Vol 4 (1) ◽  
pp. 47-57 ◽  
Author(s):  
A. Svensson ◽  
K. K. Andersen ◽  
M. Bigler ◽  
H. B. Clausen ◽  
D. Dahl-Jensen ◽  
...  
Keyword(s):  
North Atlantic ◽  
Time Scale ◽  
Ice Core ◽  
Ice Cores ◽  
The North ◽  
Annual Layer ◽  
Zone Ii ◽  
Absolute Age ◽  
Age Estimates ◽  
New Time

Abstract. The Greenland Ice Core Chronology 2005 (GICC05) is a time scale based on annual layer counting of high-resolution records from Greenland ice cores. Whereas the Holocene part of the time scale is based on various records from the DYE-3, the GRIP, and the NorthGRIP ice cores, the glacial part is solely based on NorthGRIP records. Here we present an 18 ka extension of the time scale such that GICC05 continuously covers the past 60 ka. The new section of the time scale places the onset of Greenland Interstadial 12 (GI-12) at 46.9±1.0 ka b2k (before year AD 2000), the North Atlantic Ash Zone II layer in GI-15 at 55.4±1.2 ka b2k, and the onset of GI-17 at 59.4±1.3 ka b2k. The error estimates are derived from the accumulated number of uncertain annual layers. In the 40–60 ka interval, the new time scale has a discrepancy with the Meese-Sowers GISP2 time scale of up to 2.4 ka. Assuming that the Greenland climatic events are synchronous with those seen in the Chinese Hulu Cave speleothem record, GICC05 compares well to the time scale of that record with absolute age differences of less than 800 years throughout the 60 ka period. The new time scale is generally in close agreement with other independently dated records and reference horizons, such as the Laschamp geomagnetic excursion, the French Villars Cave and the Austrian Kleegruben Cave speleothem records, suggesting high accuracy of both event durations and absolute age estimates.

scholarly journals The North Atlantic Oscillation synchronises fruit production in western European forests

Ecography ◽  
2016 ◽  
Vol 40 (7) ◽  
pp. 864-874 ◽  
Author(s):  
Marcos Fernández-Martínez ◽  
Sara Vicca ◽  
Ivan A. Janssens ◽  
Josep Maria Espelta ◽  
Josep Peñuelas
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Fruit Production ◽  
European Forests ◽  
The North ◽  
The North Atlantic ◽  
Western European ◽  
The North Atlantic Oscillation

scholarly journals Modeling dust emission response to MIS 3 millennial climate variations from the perspective of East European loess deposits

2013 ◽  
Vol 9 (1) ◽  
pp. 143-185 ◽  
Author(s):  
A. Sima ◽  
M. Kageyama ◽  
D.-D. Rousseau ◽  
G. Ramstein ◽  
Y. Balkanski ◽  
...  
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Reference Site ◽  
Dust Emission ◽  
Dust Storms ◽  
Surface Model ◽  
Climate Signal ◽  
The North ◽  
Loess Deposits ◽  
The North Atlantic

Abstract. European loess sequences of the last glacial period (~ 100–15 kyr BP) show periods of strong dust accumulation alternating with episodes of reduced sedimentation, favoring soil development. In the western part of the loess belt centered around 50° N, these variations appear to have been caused by the North Atlantic rapid climate changes: the Dansgaard-Oeschger (DO) and Heinrich (H) events. It has been recently suggested that the North-Atlantic climate signal can be detected further east, in loess deposits from Stayky (50° 05.65' N, 30° 53.92' E), Ukraine. Here we use climate and dust emission modeling to investigate this data interpretation. We focus on the areas north and northeast of the Carpathians, where loess deposits can be found, and the corresponding main dust sources must have been located as well. The simulations, performed with the LMDZ atmospheric general circulation model and the ORCHIDEE land-surface model, represent a Greenland stadial, a DO interstadial and an H event respectively. Placed in Marine Isotope Stage 3 (~ 60–25 kyr BP) conditions, they only differ by the surface conditions imposed in the North Atlantic between 30° and 63° N. The main source for the loess deposits in the studied area is identified as a dust deflation band, with two very active spots located west–northwest from our reference site. Emissions only occur between February and June. Differences from one deflation spot to another, and from one climate state to another, are explained by analyzing the relevant meteorological and surface variables. Over most of the source region, the annual emission fluxes in the "interstadial" experiment are 30 to 50% lower than the "stadial" values; they would only be about 20% lower if the inhibition of dust uplift by the vegetation were not taken into account. Assuming that lower emissions result in reduced dust deposition leads us to the conclusion that the loess-paleosol stratigraphic succession in the Stayky area reflects indeed North-Atlantic millennial variations. In the main deflation areas of Western Europe, the vegetation effect alone determined most of the ~ 50% stadial-interstadial flux differences. Even if its impact in Eastern Europe is less pronounced, this effect remains a key factor in modulating aeolian emissions at millennial timescale. Conditions favorable to initiating particularly strong dust storms within a few hundred kilometers upwind from our reference site, simulated in the month of April of the "H event" experiment, support the identification of H events as layers of particularly coarse sedimentation in some very detailed profiles.

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