Did a Beringian ice sheet once exist?

2020 ◽  
Author(s):  
Zhongshi Zhang ◽  
Qing Yan ◽  
Ran Zhang ◽  
Florence Colleoni ◽  
Gilles Ramstein ◽  
...  
Keyword(s):  
North Pacific ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Climate Modelling ◽  
Mountain Glaciers ◽  
The Past ◽  
The North ◽  
Paleoclimate Records ◽  
Glacial Landforms ◽  
The North Pacific

<p>Did a Beringian ice sheet once exist? This question was hotly debated decades ago until compelling evidence for an ice-free Wrangel Island excluded the possibility of an ice sheet forming over NE Siberia-Beringia during the Last Glacial Maximum (LGM). Today, it is widely believed that during most Northern Hemisphere glaciations only the Laurentide-Eurasian ice sheets across North America and Northwest Eurasia became expansive, while Northeast Siberia-Beringia remained ice-sheet-free. However, recent recognition of glacial landforms and deposits on Northeast Siberia-Beringia and off the Siberian continental shelf has triggered a new round of debate.These local glacial features, though often interpreted as local activities of ice domes on continental shelves and mountain glaciers on continents,   could be explained as an ice sheet over NE Siberia-Beringia. Only based on the direct glacial evidence, the debate can not be resolved. Here, we combine climate and ice sheet modelling with well-dated paleoclimate records from the mid-to-high latitude North Pacific to readdress the debate. Our simulations show that the paleoclimate records are not reconcilable with the established concept of Laurentide-Eurasia-only ice sheets. On the contrary, a Beringian ice sheet over Northeast Siberia-Beringia causes feedbacks between atmosphere and ocean, the result of which well explains the climate records from around the North Pacific during the past four glacial-interglacial cycles. Our ice-climate modelling and synthesis of paleoclimate records from around the North Pacific argue that the Beringian ice sheet waxed and waned rapidly in the past four glacial-interglacial cycles and accounted for ~10-25 m ice-equivalent sea-level change during its peak glacials. The simulated Beringian ice sheet agrees reasonably with the direct glacial and climate evidence from Northeast Siberia-Beringia, and reconciles the paleoclimate records from around the North Pacific. With the Beringian ice sheet involved, the pattern of past NH ice sheet evolution is more complex than previously thought, in particular prior to the LGM.</p>

scholarly journals Rapid waxing and waning of Beringian ice sheet reconcile glacial climate records from around North Pacific

2020 ◽  
Author(s):  
Zhongshi Zhang ◽  
Qing Yan ◽  
Ran Zhang ◽  
Florence Colleoni ◽  
Gilles Ramstein ◽  
...  
Keyword(s):  
North America ◽  
High Latitude ◽  
North Pacific ◽  
Ice Sheets ◽  
Ice Sheet ◽  
The North ◽  
Climate Records ◽  
Climate Evolution ◽  
Paleoclimate Records ◽  
Glacial Landforms

Abstract. Throughout the Pleistocene the Earth has experienced pronounced glacial-interglacial cycles, which have been debated for decades. One concept widely held is that during most glacials only the Laurentide-Eurasian ice sheets across North America and Northwest Eurasia became expansive, while Northeast Siberia-Beringia remained ice-sheet-free. However, the recognition of glacial landforms and deposits on Northeast Siberia-Beringia and off the Siberian continental shelf is beginning to call into question this paradigm. Here, we combine climate and ice sheet modelling with well-dated paleoclimate records from the mid-to-high latitude North Pacific to demonstrate the episodic occurrences of an ice sheet across Northeast Siberia-Beringia. Our simulations first show that the paleoclimate records are irreconcilable with the established paradigm of Laurentide-Eurasia-only ice sheets, and then reveal that a Beringian ice sheet over Northeast Siberia-Beringia causes feedbacks between atmosphere and ocean, the result of which better explains these climate records from around the North Pacific during the past four glacial-interglacial cycles. Our simulations propose an alternative scenario for NH ice sheet evolution, which involves the rapid waxing and waning of the Beringian ice sheet alongside the growth of the Laurentide-Eurasian ice sheets. The new scenario settles the long-standing discrepancies between the direct glacial evidence and the climate evolution from around the mid-to-high latitude North Pacific. It depicts a high complexity in glacial climates and has important implications for our understanding of the dispersal of prehistoric humans through Beringia into North America.

Evidence of meltwater pulses into the North Pacific over the last 20 ka due to the decay of Kamchatka Glaciers and Cordilleran Ice Sheet

2019 ◽  
Vol 172 ◽  
pp. 33-44 ◽  
Author(s):  
Sergey Gorbarenko ◽  
Xuefa Shi ◽  
Jianjun Zou ◽  
Tatyana Velivetskaya ◽  
Antonina Artemova ◽  
...  
Keyword(s):  
North Pacific ◽  
Ice Sheet ◽  
The North ◽  
Cordilleran Ice Sheet ◽  
The North Pacific

8. Glaciers of the past

2018 ◽  
pp. 146-152
Author(s):  
David J. A. Evans
Keyword(s):  
Numerical Models ◽  
Ice Core ◽  
Three Dimensional ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Aerial Imagery ◽  
The Past ◽  
Glacial Landforms

To reconstruct the former extent and dynamics of ice sheets and glaciers requires a knowledge of process-form relationships that goes beyond individual landform types. Instead, glacial geomorphologists need to analyse large areas of glaciated terrain in a more holistic way, combining the whole range of glacial landforms and sediments to reconstruct glacier systems of the past, a subject now known as palaeoglaciology. ‘Glaciers of the past’ explains how the combination of aerial imagery and landform analysis is used in palaeoglaciological reconstruction. Increasingly powerful computers are making it possible to compile sophisticated numerical models that use our knowledge of glaciological processes and ice-core-derived palaeoclimate data to create three-dimensional glacier and ice sheet reconstructions.

Rapid climate variability in the North Pacific Ocean during the past 95,000 years

Nature ◽  
1995 ◽  
Vol 377 (6547) ◽  
pp. 323-326 ◽  
Author(s):  
A. T. Kotilainen ◽  
N. J. Shackleton
Keyword(s):  
Pacific Ocean ◽  
Climate Variability ◽  
North Pacific ◽  
North Pacific Ocean ◽  
The Past ◽  
The North ◽  
The North Pacific

Late Pleistocene History of the North Pacific: Evidence from a Quantitative Study of Radiolaria in Core V21-173

1973 ◽  
Vol 3 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Harvey Maurice Sachs
Keyword(s):  
Late Pleistocene ◽  
North Pacific ◽  
Transfer Functions ◽  
Near Surface ◽  
The Past ◽  
The North ◽  
History Of ◽  
The North Pacific ◽  
Oceanographic Conditions ◽  
Radiolarian Assemblages

AbstractObjective quantitative estimates of paleo-oceanographic conditions in the North Pacific can be made by analyses of radiolarian assemblages. With appropriate computation, transfer functions developed in a study of surface sediments can be used to estimate oceanographic conditions in cores containing late Pleistocene radiolarian faunas. Analysis of core V21-173 indicates that conditions as warm as the Holocene were rare during the past 800,000 yr, and that the region experienced marked near-surface temperature drops correlative with Caribbean and continental records for the past 250,000 yr. A major world-wide warm event at about 400,000 yr is also indicated.

Sea Surface Temperature Changes in the Northeastern Pacific Ocean during the Past 20,000 Years and Their Relationship to Climate Change in Northwestern North America

1996 ◽  
Vol 46 (1) ◽  
pp. 48-61 ◽  
Author(s):  
Ann L. Sabin ◽  
Nicklas G. Pisias
Keyword(s):  
Pacific Ocean ◽  
North America ◽  
North Pacific ◽  
Sea Surface ◽  
The Past ◽  
The North ◽  
Northeastern Pacific ◽  
Northwestern North America ◽  
The North Pacific ◽  
Continental Climate

Modern ocean–atmosphere interactions in the northeastern Pacific Ocean have a significant effect on the climate of the west coast of North America. We present radiolarian microfossil-based temperature reconstructions for the eastern North Pacific spanning the past 20,000 yr to examine possible correlations and linkages between continental climate change and changes in sea surface temperature (SST) in the northeastern Pacific Ocean on millennial time scales. The reconstructions indicate that the regional pattern of ocean circulation off the west coast of North America was further south 15,000 cal yr B.P. than it is today, and reached its present location 13,000 cal yr B.P. The North Pacific Drift and Transition Zone were further south as a result of a more southerly North Pacific high pressure cell prior to 13,000 cal yr B.P. While two continental paleoclimate records from northwestern North America show regional differences, they also can be correlated to the SST changes. A coastal site at 48°N shows similar patterns in summer temperatures, as observed in offshore marine records of SSTs. However, an inland continental record seems to reflect more-regional-scale changes in sea surface conditions showing a thermal maximum centered at 10,000 cal yr B.P which is observed in the marine transect south of 42°N. We conclude, based on the pattern of oceanographic change as reflected in radiolarian assemblages, that changes in the past latitudinal position of the North Pacific Drift played a significant role in controlling continental climate immediately to its east, as it does in the present environment. We also conclude that during the past 20,000 yr much of the evolution of oceanographic change is related to the migration of the atmospheric pressure cells (the North Pacific high and Aleutian low) of the northeastern Pacific.

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