scholarly journals Millennial-scale iceberg discharges in the Irminger Basin during the Last Glacial Period: Relationship with the Heinrich events and environmental settings

1998 ◽  
Vol 13 (5) ◽  
pp. 433-446 ◽  
Author(s):  
Mary Elliot ◽  
Laurent Labeyrie ◽  
Gerard Bond ◽  
Elsa Cortijo ◽  
Jean-Louis Turon ◽  
...  
Keyword(s):  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Heinrich Events ◽  
The Last Glacial ◽  
Millennial Scale

scholarly journals <i>δ</i><sup>13</sup>C decreases in the upper western South Atlantic during Heinrich Stadials 3 and 2

2017 ◽  
Vol 13 (4) ◽  
pp. 345-358 ◽  
Author(s):  
Marília C. Campos ◽  
Cristiano M. Chiessi ◽  
Ines Voigt ◽  
Alberto R. Piola ◽  
Henning Kuhnert ◽  
...  
Keyword(s):  
Climate Change ◽  
South Atlantic ◽  
Meridional Overturning Circulation ◽  
Glacial Period ◽  
Last Deglaciation ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Change Events ◽  
The Last Glacial ◽  
Millennial Scale

Abstract. Abrupt millennial-scale climate change events of the last deglaciation (i.e. Heinrich Stadial 1 and the Younger Dryas) were accompanied by marked increases in atmospheric CO2 (CO2atm) and decreases in its stable carbon isotopic ratios (δ13C), i.e. δ13CO2atm, presumably due to outgassing from the ocean. However, information on the preceding Heinrich Stadials during the last glacial period is scarce. Here we present δ13C records from two species of planktonic foraminifera from the western South Atlantic that reveal major decreases (up to 1 ‰) during Heinrich Stadials 3 and 2. These δ13C decreases are most likely related to millennial-scale periods of weakening of the Atlantic meridional overturning circulation and the consequent increase (decrease) in CO2atm (δ13CO2atm). We hypothesise two mechanisms that could account for the decreases observed in our records, namely strengthening of Southern Ocean deep-water ventilation and weakening of the biological pump. Additionally, we suggest that air–sea gas exchange could have contributed to the observed δ13C decreases. Together with other lines of evidence, our data are consistent with the hypothesis that the CO2 added to the atmosphere during abrupt millennial-scale climate change events of the last glacial period also originated in the ocean and reached the atmosphere by outgassing. The temporal evolution of δ13C during Heinrich Stadials 3 and 2 in our records is characterized by two relative minima separated by a relative maximum. This w structure is also found in North Atlantic and South American records, further suggesting that such a structure is a pervasive feature of Heinrich Stadial 2 and, possibly, also Heinrich Stadial 3.

scholarly journals Controls on Millennial-Scale Atmospheric CO2 Variability During the Last Glacial Period

2018 ◽  
Vol 45 (15) ◽  
pp. 7731-7740 ◽  
Author(s):  
T. K. Bauska ◽  
E. J. Brook ◽  
S. A. Marcott ◽  
D. Baggenstos ◽  
S. Shackleton ◽  
...  
Keyword(s):  
Atmospheric Co2 ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
The Last Glacial ◽  
Millennial Scale

Link between the North and South Atlantic during the Heinrich events of the last glacial period

1999 ◽  
Vol 15 (12) ◽  
pp. 909-919 ◽  
Author(s):  
L. Vidal ◽  
R.R. Schneider ◽  
O. Marchal ◽  
T. Bickert ◽  
T.F. Stocker ◽  
...  
Keyword(s):  
South Atlantic ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Heinrich Events ◽  
The North ◽  
North And South ◽  
The Last Glacial

Millennial-scale oscillations of the westerly jet path during the last glacial period

2011 ◽  
Vol 40 (6) ◽  
pp. 1214-1220 ◽  
Author(s):  
Kana Nagashima ◽  
Ryuji Tada ◽  
Atsushi Tani ◽  
Youbin Sun ◽  
Yuko Isozaki ◽  
...  
Keyword(s):  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Westerly Jet ◽  
The Last Glacial ◽  
Millennial Scale

scholarly journals Millennial-scale climate variability during the Last Glacial period in the tropical Andes

2010 ◽  
Vol 29 (7-8) ◽  
pp. 1017-1024 ◽  
Author(s):  
S.C. Fritz ◽  
P.A. Baker ◽  
E. Ekdahl ◽  
G.O. Seltzer ◽  
L.R. Stevens
Keyword(s):  
Climate Variability ◽  
Glacial Period ◽  
Tropical Andes ◽  
Last Glacial Period ◽  
Last Glacial ◽  
The Last Glacial ◽  
Millennial Scale

scholarly journals Oceanic forcing of the Eurasian Ice Sheet on millennial time scales during the Last Glacial Period

2018 ◽  
Author(s):  
Jorge Alvarez-Solas ◽  
Rubén Banderas ◽  
Alexander Robinson ◽  
Marisa Montoya
Keyword(s):  
Time Scales ◽  
North Atlantic ◽  
Climate Changes ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
The Last Glacial ◽  
Millennial Scale

Abstract. The last glacial period (LGP; ca.110–10 ka BP) was marked by the existence of two types of abrupt climatic changes, Dansgaard-Oeschger (DO) and Heinrich (H) events. Although the mechanisms behind these are not fully understood, it is generally accepted that the presence of ice sheets played an important role in their occurrence. While an important effort has been made to investigate the dynamics and evolution of the Laurentide Ice Sheet (LIS) during this period, the Eurasian Ice Sheet (EIS) has not received much attention, in particular from a modeling perspective. However, meltwater discharge from this and other ice sheets surrounding the Nordic Seas is often implied as a potential cause of ocean instabilities that lead to glacial abrupt climate changes. Thus, a better understanding of its variations during the LGP is important to understand its role in glacial abrupt climate changes. Here we investigate the response of the EIS to millennial-scale climate variability during the LGP. We use a hybrid, three-dimensional, thermomechanical ice-sheet model that includes ice shelves and ice streams. The model is forced offline through a novel perturbative approach that includes the effect of both atmospheric and oceanic variations and provides a more realistic treatment of millennial-scale climatic variability than conventional methods. Our results show that the EIS responds with enhanced ice discharge in phase with interstadial warming in the North Atlantic when forced with surface ocean temperatures. Conversely, when subsurface ocean temperatures are used, enhanced ice discharge occurs both during stadials and at the beginning of the interstadials. Separating the atmospheric and oceanic effects demonstrates the major role of the ocean in controlling the dynamics of the EIS on millennial time scales. While the atmospheric forcing alone is only able to produce modest iceberg discharges, warming of the ocean leads to higher rates of iceberg discharges as a result of relatively strong basal melting at the margins of the ice sheet. Together with previous work, our results provide a consistent explanation for the response of the LIS and the EIS to glacial abrupt climate changes, and highlight the need for stronger constraints on the local North Atlantic behavior in order to improve our understanding of the ice sheet's glacial dynamics.

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

2010 ◽  
Vol 6 (1) ◽  
pp. 135-183 ◽  
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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