Constraints on the duration and freshwater release of Heinrich event 4 through isotope modelling

Nature ◽  
2004 ◽  
Vol 432 (7015) ◽  
pp. 379-382 ◽  
Author(s):  
D. Roche ◽  
D. Paillard ◽  
E. Cortijo
Keyword(s):  
Heinrich Event ◽  
Freshwater Release ◽  
Isotope Modelling

scholarly journals The Last Glacial Maximum and Heinrich Event 1 in terms of climate and vegetation around the Alboran Sea: a preliminary model-data comparison

2005 ◽  
Vol 337 (10-11) ◽  
pp. 983-992 ◽  
Author(s):  
Masa Kageyama ◽  
Nathalie Combourieu Nebout ◽  
Pierre Sepulchre ◽  
Odile Peyron ◽  
Gerhard Krinner ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Model Data ◽  
Last Glacial ◽  
Data Comparison ◽  
Heinrich Event ◽  
Preliminary Model ◽  
The Last Glacial Maximum ◽  
Heinrich Event 1 ◽  
The Last Glacial

The timing of deglaciation from mountain summits to cirques in Wales: 10Be and 26Al exposure dates from Cadair Idris

2021 ◽  
Author(s):  
Philip Hughes ◽  
Neil Glasser ◽  
David Fink ◽  
Jason Dortch ◽  
Reka Fülöp ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Lake Basin ◽  
Summit Area ◽  
Sheet Surface ◽  
Ice Cap ◽  
Heinrich Event ◽  
Level Ice ◽  
High Level ◽  
Exposure Ages ◽  
Later Phase

<p>Cosmogenic <sup>10</sup>Be and <sup>26</sup>Al exposure ages from 20 erratic samples collected from Cadair Idris (893 m), a mountain in southern Snowdonia, Wales, provide evidence for the timing of deglaciation from summits to cirques at the end of the Late Pleistocene. The summit of the mountain is characterised by intensely modified frost-shattered surfaces that have long been identified as a representing a former nunatak. Numerous glacially-transported quartz boulders on the highest ground indicate that ice overran the summit at some point in the Pleistocene. Two quartz boulders, one with preserved striations, sampled at c. 856 m near the summit of Cadair Idris yielded consistent <sup>10</sup>Be and <sup>26</sup>Al paired exposure ages of 75 ka to 60 ka (using a high-latitude sea level <sup>10</sup>Be spallation production rate of 4.20 at/g/y, scaled by the Lal/Stone scheme). A glacially polished bedrock quartzite outcrop at 735 m gave an age of 17.5 ka. Immediately below this, cirque and down-valley recessional moraine ages, covering an elevation of 480 m to 350 m ranged from 10 to 15 ka respectively.</p><p>These results confirm that Cadair Idris was overridden by the Welsh Ice Cap during marine isotope stage (MIS) 4, when ice was thicker than at the global last glacial maximum (LGM) in MIS 2. This is consistent with findings from northern Snowdonia. The highest Welsh summits, including Cadair Idris, emerged above a thinning Welsh Ice Cap (British Irish Ice Sheet) during the transition from MIS 4 to 3. The summit area above ~800 m then stood as nunataks above the LGM ice sheet surface in MIS 2. The Welsh Ice Cap then rapidly thinned over Cadair Idris at ~20-17 ka based on ages from high-level ice-moulded bedrockThis is supported by more new ages from high-level paired erratics and bedrock samples on several other mountains throughout Snowdonia, leading to a phase of alpine-style deglaciation. Valley glaciers initiated their retreat up-valley from ~17 to 14 ka after Heinrich Event 1. A later phase of glacier stabilisation or still stand formation produced classic cirque moraines near the rim of a present cirque lake basin (480 m elevation) yielding <sup>10</sup>Be ages of 13-10 ka during the Younger Dryas.</p>

scholarly journals Patterns of millennial variability over the last 500 ka

2010 ◽  
Vol 6 (3) ◽  
pp. 295-303 ◽  
Author(s):  
M. Siddall ◽  
E. J. Rohling ◽  
T. Blunier ◽  
R. Spahni
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Glacial Cycles ◽  
The North ◽  
The North Atlantic ◽  
Paleoclimate Records ◽  
Temperature Proxy ◽  
Freshwater Release ◽  
Glacial Periods ◽  
Climate Events

Abstract. Millennial variability is a robust feature of many paleoclimate records, at least throughout the last several glacial cycles. Here we use the mean signal from Antarctic climate events 1 to 4 to probe the EPICA Dome C temperature proxy reconstruction through the last 500 ka for similar millennial-scale events. We find that clusters of millennial events occurred in a regular fashion over half of the time during this with a mean recurrence interval of 21 kyr. We find that there is no consistent link between ice-rafted debris deposition and millennial variability. Instead we speculate that changes in the zonality of atmospheric circulation over the North Atlantic form a viable alternative to freshwater release from icebergs as a trigger for millennial variability. We suggest that millennial changes in the zonality of atmospheric circulation over the North Atlantic are linked to precession via sea-ice feedbacks and that this relationship is modified by the presence of the large, Northern Hemisphere ice sheets during glacial periods.

scholarly journals Marine productivity response to Heinrich events: a model-data comparison

2012 ◽  
Vol 8 (5) ◽  
pp. 1581-1598 ◽  
Author(s):  
V. Mariotti ◽  
L. Bopp ◽  
A. Tagliabue ◽  
M. Kageyama ◽  
D. Swingedouw
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Circulation Model ◽  
Global Ocean ◽  
Biogeochemical Model ◽  
Heinrich Events ◽  
The North ◽  
Heinrich Event ◽  
The North Atlantic ◽  
Marine Productivity

Abstract. Marine sediments records suggest large changes in marine productivity during glacial periods, with abrupt variations especially during the Heinrich events. Here, we study the response of marine biogeochemistry to such an event by using a biogeochemical model of the global ocean (PISCES) coupled to an ocean-atmosphere general circulation model (IPSL-CM4). We conduct a 400-yr-long transient simulation under glacial climate conditions with a freshwater forcing of 0.1 Sv applied to the North Atlantic to mimic a Heinrich event, alongside a glacial control simulation. To evaluate our numerical results, we have compiled the available marine productivity records covering Heinrich events. We find that simulated primary productivity and organic carbon export decrease globally (by 16% for both) during a Heinrich event, albeit with large regional variations. In our experiments, the North Atlantic displays a significant decrease, whereas the Southern Ocean shows an increase, in agreement with paleo-productivity reconstructions. In the Equatorial Pacific, the model simulates an increase in organic matter export production but decreased biogenic silica export. This antagonistic behaviour results from changes in relative uptake of carbon and silicic acid by diatoms. Reasonable agreement between model and data for the large-scale response to Heinrich events gives confidence in models used to predict future centennial changes in marine production. In addition, our model allows us to investigate the mechanisms behind the observed changes in the response to Heinrich events.

Climate and landscape during Heinrich Event 3 in south-western Europe: the small-vertebrate association from Galls Carboners cave (Mont-ral, Tarragona, north-eastern Iberia)

2014 ◽  
Vol 29 (2) ◽  
pp. 130-140 ◽  
Author(s):  
JUAN MANUEL LÓPEZ-GARCÍA ◽  
HUGUES-ALEXANDRE BLAIN ◽  
MARIA BENNÀSAR ◽  
JOSEP ANTONI ALCOVER ◽  
SANDRA BAÑULS-CARDONA ◽  
...  
Keyword(s):  
Western Europe ◽  
Heinrich Event ◽  
North Eastern ◽  
Small Vertebrate

Paleoceanographic evolution of the SW Svalbard margin (76°N) since 20,000 14C yr BP

2007 ◽  
Vol 67 (1) ◽  
pp. 100-114 ◽  
Author(s):  
Tine L. Rasmussen ◽  
Erik Thomsen ◽  
Marta A. Ślubowska ◽  
Simon Jessen ◽  
Anders Solheim ◽  
...  
Keyword(s):  
Surface Water ◽  
Water Mass ◽  
Atlantic Water ◽  
Subsurface Water ◽  
Planktic Foraminifera ◽  
Surface Conditions ◽  
Polar Surface ◽  
Warm Core ◽  
Heinrich Event ◽  
Benthic Environment

AbstractTwo cores from the southwestern shelf and slope of Storfjorden, Svalbard, taken at 389 m and 1485 m water depth have been analyzed for benthic and planktic foraminifera, oxygen isotopes, and ice-rafted debris. The results show that over the last 20,000 yr, Atlantic water has been continuously present on the southwestern Svalbard shelf. However, from 15,000 to 10,000 14C yr BP, comprising the Heinrich event H1 interval, the Bølling–Allerød interstades and the Younger Dryas stade, it flowed as a subsurface water mass below a layer of polar surface water. In the benthic environment, the shift to interglacial conditions occurred at 10,000 14C yr BP. Due to the presence of a thin upper layer of polar water, surface conditions remained cold until ca. 9000 14C yr BP, when the warm Atlantic water finally appeared at the surface. Neither extensive sea ice cover nor large inputs of meltwater stopped the inflow of Atlantic water. Its warm core was merely submerged below the cold polar surface water.

Heinrich event imprints in the Okinawa Trough: evidence from oxygen isotope and planktonic foraminifera

2001 ◽  
Vol 176 (1-4) ◽  
pp. 133-146 ◽  
Author(s):  
Tiegang Li ◽  
Zhenxia Liu ◽  
Michael A Hall ◽  
Serge Berne ◽  
Yoshi Saito ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Okinawa Trough ◽  
Planktonic Foraminifera ◽  
Heinrich Event ◽  
The Okinawa Trough
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