Unstable ice stream in Greenland during the Younger Dryas cold event

Geology ◽  
2014 ◽  
Vol 42 (9) ◽  
pp. 759-762 ◽  
Author(s):  
Vincent Rinterknecht ◽  
Vincent Jomelli ◽  
Daniel Brunstein ◽  
Vincent Favier ◽  
Valérie Masson-Delmotte ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Cold Event ◽  
Ice Stream

Timing and duration of North American glacial lake discharges and the Younger Dryas climate reversal

2011 ◽  
Vol 75 (3) ◽  
pp. 541-551 ◽  
Author(s):  
John A. Rayburn ◽  
Thomas M. Cronin ◽  
David A. Franzi ◽  
Peter L.K. Knuepfer ◽  
Debra A. Willard
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North American ◽  
Younger Dryas ◽  
Ice Cores ◽  
Cold Event ◽  
Lawrence Estuary ◽  
The North ◽  
The North Atlantic ◽  
Proglacial Lake

AbstractRadiocarbon-dated sediment cores from the Champlain Valley (northeastern USA) contain stratigraphic and micropaleontologic evidence for multiple, high-magnitude, freshwater discharges from North American proglacial lakes to the North Atlantic. Of particular interest are two large, closely spaced outflows that entered the North Atlantic Ocean via the St. Lawrence estuary about 13,200–12,900 cal yr BP, near the beginning of the Younger Dryas cold event. We estimate from varve chronology, sedimentation rates and proglacial lake volumes that the duration of the first outflow was less than 1 yr and its discharge was approximately 0.1 Sv (1 Sverdrup = 106 m3 s−1). The second outflow lasted about a century with a sustained discharge sufficient to keep the Champlain Sea relatively fresh for its duration. According to climate models, both outflows may have had sufficient discharge, duration and timing to affect meridional ocean circulation and climate. In this report we compare the proglacial lake discharge record in the Champlain and St. Lawrence valleys to paleoclimate records from Greenland Ice cores and Cariaco Basin and discuss the two-step nature of the inception of the Younger Dryas.

Eyed Bone Needles from a Younger Dryas Paleoindian Component at Tule Lake Rock Shelter, Northern California

2014 ◽  
Vol 79 (4) ◽  
pp. 776-781 ◽  
Author(s):  
Jon M. Erlandson ◽  
Douglas J. Kennett ◽  
Brendan J. Culleton ◽  
Ted Goebel ◽  
Greg C. Nelson ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Northern California ◽  
Cold Event ◽  
Rock Shelter ◽  
Terminal Pleistocene ◽  
Klamath Basin ◽  
High Desert ◽  
Tule Lake ◽  
Basin Area ◽  
Small Bone

AbstractThe geographic and chronological distribution of eyed bone needles in North American Paleoindian sites led Osborn (2014) to propose that these distinctive artifacts date primarily to the Terminal Pleistocene Younger Dryas Cold Event and were essential to making close-fitting clothes needed to survive frigid winter conditions. Our study of a museum collection from Tule Lake Rock Shelter (CA-SIS-218A) in the high Klamath Basin area supports Osborn’s argument. We present nine high-precision accelerator mass spectrometry (AMS) radiocarbon assays from a 2.5 m deep cultural sequence, demonstrating that Paleoindians occupied the site primarily during the Younger Dryas. Although only about .5 m3of the Paleoindian deposits at CA-SIS-218A were excavated, fragments of four small bone needles were recovered, three of which contain whole or partial eyes. Two fragments of large mammal cortical bone from the same levels contain remnants of “groove and snap” fractures that may be related to the production of needle blanks. The bone needles from Tule Lake Rock Shelter extend the geographic range of these distinctive Paleoindian artifacts into the high desert region of Northern California.

scholarly journals Radiocarbon Age of the Laacher See Tephra: 11,230 ± 40 BP

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 149-154 ◽  
Author(s):  
Irena Hajdas ◽  
Susan D. Ivy-Ochs ◽  
Georges Bonani ◽  
André F. Loiter ◽  
Bernd Zolitschka ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Younger Dryas ◽  
Cold Event ◽  
Time Marker ◽  
Terrestrial Plant ◽  
Plant Macrofossil ◽  
Radiocarbon Age ◽  
Ash Layer ◽  
Laacher See Tephra

The Laacher Sec Tephra (LST) layer provides a unique and invaluable time marker in European sediments with increasing importance because it occurs just before the onset of the Younger Dryas (YD) cold event. As the YD begins ca. 200 calendar years after the LST was deposited, accurate determination of the radiocarbon age of this ash layer will lead to a more accurate age assignment for the beginning of the YD. On the basis of 12 terrestrial plant macrofossil 14C ages derived from sediments from Soppensee, Holzmaar and Schlakenmehrener Maar, we found an age of at least 11,230 ± 40 bp for the LST event. This is ca. 200 yr older than the often reported age of 11,000 ± 50 bp (van den Bogaard and Schmincke 1985).

Tephrochronological evidence of a later Younger Dryas ice-sheet maximum in central Norway

2021 ◽  
Author(s):  
Simon A. Larsson ◽  
Stefan Wastegård ◽  
Fredrik Høgaas
Keyword(s):  
Radiocarbon Dating ◽  
Ice Sheet ◽  
Younger Dryas ◽  
Coastal Lake ◽  
Cold Event ◽  
Western Norway ◽  
Scandinavian Ice Sheet ◽  
Marine Fossils ◽  
Ice Sheet Dynamics ◽  
Southern Norway

<p>The Scandinavian Ice Sheet responded time-transgressively to the Younger Dryas (Greenland Stadial 1) cold event with large regional variations. Around Trondheimsfjorden in central Norway, the Tautra Moraines and the Hoklingen Moraines have long been assumed to have formed by glacial readvances during this event, as they have been dated to c. 12.7 and 11.6 cal. ka BP respectively (Olsen et al., 2015), mainly based on radiocarbon dating of often marine fossils. The Tautra Moraines, being the outer ridges of the two, should thus represent the maximum ice-sheet extent in this region during the Younger Dryas.</p><p>This ice-front position established a pro-glacial lake west of present-day Leksvik village on the Fosen peninsula (Selnes, 1982), which covered the Lomtjønnin lakes and Lomtjønnmyran fens, and drained through a spillway via Lake Rørtjønna. Some 20 km inland (northeast) from this location, inside the Tautra Moraines, the location of the Damåsmyran bog was covered by the ice sheet at that time.</p><p>By examining sediments from these sites for occurrences of volcanic ashes (visible and cryptotephra), combined with radiocarbon dating, we find that the ice front remained at the Tautra Moraines until the late Younger Dryas, contrary to the previous chronology (and overriding the suggested formation age of the Hoklingen Moraines). These findings comply with several recent reconstructions of the deglaciation at other sites in western (Lohne et al., 2012; Mangerud et al., 2016) and southern Norway (Romundset et al., 2019) and are a strong example of the usefulness of tephrochronology in the reconstruction of past ice-sheet dynamics.</p><p> </p><p><strong>References</strong></p><p>Lohne, Ø.S., Mangerud, J. & Svendsen, J.I. (2012) Timing of the Younger Dryas glacial maximum in Western Norway. <em>Journal of Quaternary Science</em>, vol. 27, pp. 81–88.</p><p>Mangerud, J., Aarseth, I., et al. (2016) A major re-growth of the Scandinavian Ice Sheet in western Norway during Allerød–Younger Dryas. <em>Quaternary Science Reviews</em>, vol. 132, pp. 175–205.</p><p>Olsen, L., Høgaas, F. & Sveian, H. (2015) Age of the Younger Dryas ice-marginal substages in Mid-Norway—Tautra and Hoklingen, based on a compilation of 14C-dates. <em>Norges geologiske undersøkelse Bulletin</em>, vol. 454, pp. 1–13.</p><p>Romundset, A., Lakeman, T.R. & Høgaas, F. (2019) Coastal lake records add constraints to the age and magnitude of the Younger Dryas ice-front oscillation along the Skagerrak coastline in southern Norway. <em>Journal of Quaternary Science</em>, vol. 34, pp. 112–124.</p><p>Selnes, H. (1982) Paleo-økologiske undersøkelser omkring israndavsetninger på Fosenhalvøya, Midt-Norge. Thesis at the Department of Botany, University of Trondheim.</p>

Numerical modelling provides evidence of a Baltic Ice Stream during the Younger Dryas

Boreas ◽  
2008 ◽  
Vol 22 (2) ◽  
pp. 77-86 ◽  
Author(s):  
PER HOLMLUND ◽  
JAMES FASTOOK
Keyword(s):  
Numerical Modelling ◽  
Younger Dryas ◽  
Ice Stream

Sudden climate transitions during the Quaternary

1999 ◽  
Vol 23 (1) ◽  
pp. 1-36 ◽  
Author(s):  
Jonathan Adams ◽  
Mark Maslin ◽  
Ellen Thomas
Keyword(s):  
Climate Change ◽  
Ocean Circulation ◽  
Younger Dryas ◽  
Ice Cover ◽  
Ice Age ◽  
Cold Event ◽  
Heinrich Events ◽  
The Past ◽  
Eemian Interglacial ◽  
Climate Transitions

The time span of the past few million years has been punctuated by many rapid climate transitions, most of them on timescales of centuries to decades. The most detailed information is available for the Younger Dryas-to-Holocene stepwise change around 11 500 years ago, which seems to have occurred over a few decades. The speed of this change is probably representative of similar but less well studied climate transitions during the last few hundred thousand years. These include sudden cold events (Heinrich events/stadials), warm events (interstadials) and the beginning and ending of long warm phases, such as the Eemian interglacial. Detailed analysis of terrestrial and marine records of climate change will, however, be necessary before we can say confidently on what timescale these events occurred; they almost certainly did not take longer than a few centuries. Various mechanisms, involving changes in ocean circulation and biotic productivity, changes in atmospheric concentrations of greenhouse gases and haze particles, and changes in snow and ice cover, have been invoked to explain sudden regional and global transitions. We do not know whether such changes could occur in the near future as a result of human effects on climate. Phenomena such as the Younger Dryas and Heinrich events might only occur in a ‘glacial’ world with much larger ice sheets and more extensive sea-ice cover. A major sudden cold event, however, did probably occur under global climate conditions similar to those of the present, during the Eemian interglacial around 122 000 years ago. Less intensive, but significant rapid climate changes also occurred during the present (Holocene) interglacial, with cold and dry phases occurring on a 1500-year cycle, and with climate transitions on a decade-to-century timescale. In the past few centuries, smaller transitions (such as the ending of the Little Ice Age at about AD 1650) probably occurred over only a few decades at most. All evidence indicates that long-term climate change occurs in sudden jumps rather than incremental changes.

Expression of the Younger Dryas cold event in the Carpathian Mountains, Ukraine?

2012 ◽  
Vol 39 ◽  
pp. 106-114 ◽  
Author(s):  
V. Rinterknecht ◽  
A. Matoshko ◽  
Y. Gorokhovich ◽  
D. Fabel ◽  
S. Xu
Keyword(s):  
Younger Dryas ◽  
Carpathian Mountains ◽  
Cold Event

Putting the Younger Dryas cold event into context

2010 ◽  
Vol 29 (9-10) ◽  
pp. 1078-1081 ◽  
Author(s):  
Wallace S. Broecker ◽  
George H. Denton ◽  
R. Lawrence Edwards ◽  
Hai Cheng ◽  
Richard B. Alley ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Cold Event
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