Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf

Geibert, Walter; Matthießen, Jens; Stimac, Ingrid; Wollenburg, Jutta E; Stein, Rüdiger

doi:10.1038/s41586-021-03186-y

Cited by 49 publications

(75 citation statements)

References 82 publications

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“…The idea of recurrent global ice ages needs a profound reconsideration. The most abundant oxygen isotope is the lightest 16 O (99.75%), the share of the heaviest 18 O is 0.20%, and that of the 17 O is 0.04%. Hydrogen has two stable isotopes, 1 H (99.98%) and 2 H (deuterium, 0.02%) and radioactive tritium 3 H (traces).…”

Section: Validity Of the Milankovitch Cyclementioning

confidence: 99%

“…The water vapor gradient heading from the tropics to the poles gradually becomes more and more depleted of 18 O. On the ice caps in Greenland and Antarctica relatively more H 216 O is precipitated as snow. The ratio of 18 O to16 O (marked as δ 18 O) from the ice core samples is used as a proxy to determine the eras of ice ages on Earth 81.However, in the poles during the continuous 4 to 6 months of summer sunshine, a portion of snow evaporates.…”

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confidence: 99%

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The Formation of the Sahara Desert: Evidence for the Slow Ending of the Great Ice Age

Hänninen¹

2021

eer

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The aim of this meta-study is to provide an understanding of the events which slowly ended the Great Ice Age (GIA) and caused the formation of the Sahara Desert. During the GIA, a layer of floating ice 900 m thick in the Arctic Ocean and grounded ice in the North Sea prevented the flow of the Gulf Stream into the Arctic Ocean. An 8-km layer of salt at the bottom of the Gulf of Mexico suggests that the gulf has been an inland sea for a long period. It might have been separated from the Atlantic Ocean by an overflow via the Straits of Florida and a land bridge in the Yucatan Channel, which was reflected the North Equatorial Current (NEC) flow towards the coast of Northwest Africa as the GIA-Gulf Stream (GIA-GS). During the GIA, the return waters by the GIA-GS were warm, and the Sahara was "green." About 11,300 to 11,600 years ago, an earthquake might have cut the land bridge connecting the gulf to the Atlantic Ocean. This allowed the Gulf Stream Currents (GSC) to occupy their present flow route. Within 4,000 to 5,000 years, grounded and floating ice and continental glaciers had melted and the global sea level risen by 10 to 15 meters. By then, the return flow of water carried by the GSC into the Arctic Ocean was fully developed: first via undercurrents (mainly) into the Labrador Sea, and then from there to the coast of Northwest Africa as the North Atlantic Undercurrent (NAUC). Its upwelling waters desiccated the sea-air entering the Sahara. Paleobiological, paleohydrological, and paleontological observations confirm that the drying of the Sahara started in earnest about 6,000 years ago.

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Section: Validity Of the Milankovitch Cyclementioning

confidence: 99%

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confidence: 99%

The Formation of the Sahara Desert: Evidence for the Slow Ending of the Great Ice Age

Hänninen¹

2021

eer

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“…For example, the Eurasian Ice Sheet (EAIS) dammed numerous glacial lakes in Siberia (Svendsen et al., 2004) and discharged a large amount of materials along the lakes' flow paths into basins during glaciation retreats (Jakobsson et al., 2016). Furthermore, thick ice shelves blocked the output of freshwater, leading to its accumulation in the middle and deep layers of the Arctic Ocean (Geibert et al., 2021). The Laurentide Ice Sheet (LIS) is also speculated to have driven global rapid cooling events during the Younger Dryas (∼12.9–11.5 ka) and at 8.2 ka (Alley et al., 1999).…”

Section: Introductionmentioning

confidence: 99%

Sedimentary Record of Glacial Impacts and Melt Water Discharge off the East Siberian Continental Margin, Arctic Ocean

et al. 2022

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The East Siberian Continental Margin is a major constituent of the western Arctic Ocean, ideal for studying the evolutionary history of the Siberian Ice Sheet (SIS) based on its unique geographical location and medium‐depth bathymetry. For this study, the sedimentary core CHINARE‐ARC07‐E25 (E25) was analyzed, revealing nearly continuous stable oxygen isotope and mineralogy records that preserved scenarios of the SIS development. Lithostratigraphic evidence suggests that the stratigraphic range of E25 extends to marine isotope stage (MIS) 7. Stable oxygen isotope analysis reveals multiple strong, light‐oxygen isotopic excursions since the penultimate glacial, accompanied by multiple patterns of ice rafted debris content and mineralogy. Based on these isotopic events, the potential factors causing the excursions and the provenance of drainage were evaluated. It was found that the excursion events recorded in pink‐white carbonate detritus layers could be related to the retreat of the Laurentide Ice Sheet. The most typical events, occurring during the deglaciation periods of MIS6/5e and MIS4/3 to early MIS3, were characterized by involving a mixture of two or more sources, and could be used to trace the activity of the SIS, which has been ignored in previous studies. Findings of this study are expected to advance the understanding of SIS contribution to the western Arctic Ocean basin development, which is important for interpreting global climate change behavior of similar ice sheets in the Arctic region.

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“…This assumption requires that 230 Th xs is incorporated into the sediments with a more or less constant initial activity (Ku, 1976; Ku & Broecker, 1966; Osmond, 1979). In the Arctic Ocean, however, sedimentation rates (and the 230 Th xs activities) have varied considerably over glacial‐interglacial cycles (Finkel et al., 1977; Geibert et al., 2021; Hillaire‐Marcel et al., 2017; Not & Hillaire‐Marcel, 2010; Polyak et al., 2004, 2009; Spielhagen et al., 2004; Wang et al., 2018). Thus, the exponential regression model may not provide robust sedimentation rate (or sediment age) estimates (Somayajulu et al., 1989).…”

Section: Introductionmentioning

confidence: 99%

“…A recent study (Geibert et al, 2021) proposed a freshwater Arctic Ocean to interpret two major 230 Th xs -poor sections in sediment cores from the central Arctic and the Nordic Seas (because the production of 230 Th is subject to U, which is proportional to salinity; . The two 230 Th xs -poor sections were stratigraphically assigned to MIS 4 and 6, thus, inferred thick ice shelf during these two glacial periods (Geibert et al, 2021). The first 230 Th xs -poor interval in Geibert et al (2021) corresponds to section P1 (14-26 cm) in core MA01, which has been dated to MIS 3 by 14 C, supported by high Mn content and abundant foraminifera in this interval (Figure 5;Xiao et al, 2020).…”

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confidence: 99%

Driving Mechanisms of Sedimentary ²³⁰Th and ²³¹Pa Variability in the Western Arctic Ocean Through the Last Glacial Cycle

Wei

Wang

et al. 2021

Paleoceanog and Paleoclimatol

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Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf

Cited by 49 publications

References 82 publications

The Formation of the Sahara Desert: Evidence for the Slow Ending of the Great Ice Age

The Formation of the Sahara Desert: Evidence for the Slow Ending of the Great Ice Age

Sedimentary Record of Glacial Impacts and Melt Water Discharge off the East Siberian Continental Margin, Arctic Ocean

Driving Mechanisms of Sedimentary ²³⁰Th and ²³¹Pa Variability in the Western Arctic Ocean Through the Last Glacial Cycle

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Glacial episodes of a freshwater Arctic Ocean covered by a thick ice shelf

Cited by 49 publications

References 82 publications

The Formation of the Sahara Desert: Evidence for the Slow Ending of the Great Ice Age

The Formation of the Sahara Desert: Evidence for the Slow Ending of the Great Ice Age

Sedimentary Record of Glacial Impacts and Melt Water Discharge off the East Siberian Continental Margin, Arctic Ocean

Driving Mechanisms of Sedimentary 230Th and 231Pa Variability in the Western Arctic Ocean Through the Last Glacial Cycle

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Driving Mechanisms of Sedimentary ²³⁰Th and ²³¹Pa Variability in the Western Arctic Ocean Through the Last Glacial Cycle