Radiocarbon data from North Atlantic marine sediments directly linked to millennial-scale climate variability through the last glacial period

2012 ◽  
Vol 279-280 ◽  
pp. 29
Author(s):  
William Austin
Keyword(s):  
Climate Variability ◽  
Marine Sediments ◽  
North Atlantic ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Radiocarbon Data ◽  
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.

North Atlantic forcing of millennial-scale Indo-Australian monsoon dynamics during the Last Glacial period

2013 ◽  
Vol 72 ◽  
pp. 159-168 ◽  
Author(s):  
Rhawn F. Denniston ◽  
Karl-Heinz Wyrwoll ◽  
Yemane Asmerom ◽  
Victor J. Polyak ◽  
William F. Humphreys ◽  
...  
Keyword(s):  
North Atlantic ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Australian Monsoon ◽  
Last Glacial ◽  
Monsoon Dynamics ◽  
The Last Glacial ◽  
Millennial Scale

Corrigendum to “North Atlantic forcing of millennial-scale Indo-Australian monsoon dynamics during the Last Glacial period” [Quat. Sci. Rev. 72 (2013) 159–168]

2017 ◽  
Vol 161 ◽  
pp. 134
Author(s):  
Rhawn F. Denniston ◽  
Karl-Heinz Wyrwoll ◽  
Yemane Asmerom ◽  
Victor J. Polyak ◽  
William F. Humphreys ◽  
...  
Keyword(s):  
North Atlantic ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Australian Monsoon ◽  
Last Glacial ◽  
Monsoon Dynamics ◽  
The Last Glacial ◽  
Millennial Scale

scholarly journals Ocean-driven millennial-scale variability of the Eurasian ice sheet during the last glacial period simulated with a hybrid ice-sheet–shelf model

2019 ◽  
Vol 15 (3) ◽  
pp. 957-979 ◽  
Author(s):  
Jorge Alvarez-Solas ◽  
Rubén Banderas ◽  
Alexander Robinson ◽  
Marisa Montoya
Keyword(s):  
Climate Variability ◽  
Climate Changes ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Perturbative Approach ◽  
Last Glacial ◽  
The Last Glacial ◽  
Millennial Scale

Abstract. The last glacial period (LGP; ca. 110–10 kyr 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 comprehension of the evolution of the EIS 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 off-line via a novel perturbative approach that, as opposed to conventional methods, clearly differentiates between the spatial patterns of millennial-scale and orbital-scale climate variability. Thus, it provides a more realistic treatment of the forcing at millennial timescales. The effect of both atmospheric and oceanic variations are included. 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 timescales. 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. Our results clearly show the capability of the EIS to react to glacial abrupt climate changes, and highlight the need for stronger constraints on the ice sheet's glacial dynamics and climate–ocean interactions.

Ecological thresholds and patterns of millennial-scale climate variability: The response of vegetation in Greece during the last glacial period

Geology ◽  
2004 ◽  
Vol 32 (2) ◽  
pp. 109 ◽  
Author(s):  
P.C. Tzedakis ◽  
M.R. Frogley ◽  
I.T. Lawson ◽  
R.C. Preece ◽  
I. Cacho ◽  
...  
Keyword(s):  
Climate Variability ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Ecological Thresholds ◽  
Last Glacial ◽  
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.

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