Moisture supply for northern ice-sheet growth during the Last Glacial Maximum

Hebbeln, Dierk; Dokken, Trond; Andersen, Espen; Hald, Morten; Elverhøi, Anders

doi:10.1038/370357a0

Cited by 250 publications

(175 citation statements)

References 28 publications

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“…This is conform with warming episodes described for the western Svalbard margin Ž . Hebbeln et al, 1994;Dokken and Hald, 1996 and implies huge amounts of moisture evaporating to support the final build-up of the SBIS during peak glacials. Enhanced preservation of MOM, indicated by low short-chain n-alkanes and chlorine concentrations, which could confirm seasonally ice-free conditions, is almost diminished due to intense flux of Ž .…”

Section: Glacialsmentioning

confidence: 99%

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A multiproxy approach to reconstruct the environmental changes along the Eurasian continental margin over the last 150 000 years

et al. 2000

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Section: Glacialsmentioning

confidence: 99%

“…Hebbeln et al, 1994;Knies et al, 1999 . Major deglaciation of the ice-sheets between 15.4 and 13.3 14 C kyr can be traced in sediments of the central Arctic Ocean and the Fram Strait by d 18 O meltwater Ž spikes e.g., Jones and Keigwin, 1988;Stein et al, .…”

Section: Introductionmentioning

confidence: 99%

A multiproxy approach to reconstruct the environmental changes along the Eurasian continental margin over the last 150 000 years

et al. 2000

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“…First, during intervals of the Late Weichselian, our biomarker record indicates extended periods of near-perennial sea-ice cover (29-27.5 kyr bp and 23.5-17 kyr bp; Fig. 2), yet high fluxes of planktic and benthic foraminifera have been identified previously in PS2837-5, and these were attributed to a stronger though, significantly, subsurface input of warm Atlantic water 11,23 during so-called high-productive events 29 . We suggest that a temperate subsurface layer, causing thinning and short-term opening of the ice sheet during summer months (Fig.…”

mentioning

confidence: 99%

Variability of sea-ice conditions in the Fram Strait over the past 30,000 years

Müller

Massé²,

Stein³

et al. 2009

Nature Geosci

190

181

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Sea ice is a critical component of the climate system: variations in sea-ice cover affect the albedo of polar regions, and also the rate of deepwater formation 1,2 . Changes in the sea-ice cover of the North Atlantic Ocean are thought to have been related to abrupt climate changes throughout the last glacial termination 3 , but reconstructions of sea-ice conditions are rare. Here we use the sedimentary abundance of the IP 25 and brassicasterol biomarkers, produced by sea-ice-associated diatoms and open-water phytoplankton, respectively, to generate a record of sea-ice conditions in the northernmost Atlantic Ocean for the past 30,000 years. Our reconstruction shows that a stationary margin between sea-ice cover and the open ocean existed during the Last Glacial, although perennial sea-ice cover prevailed for most of the Last Glacial Maximum. An early warming about 14,000 years ago was associated with ice-free conditions; however, seasonal sea ice was present throughout the Holocene. We find temporal links between our record of sea ice and reconstructions of the amount of relatively warm Atlantic water advected into the Nordic Seas 4,5 . We therefore conclude that changes in sea-ice conditions are linked to regional and global climate anomalies and oceanographic circulation in the North Atlantic.The distribution of sea ice in Fram Strait, the only deepwater connection (∼2,600 m mean water depth) between the Arctic and Atlantic oceans, is mainly controlled by the inflow of temperate water from the North Atlantic along the western continental margin of Spitsbergen through the Norwegian and West Spitsbergen currents 1 . In contrast, the East Greenland current carries cold water (and sea ice) southward through this gateway 1 (Fig. 1). The relative contributions of these currents strongly influence the thermohaline circulation, thus contributing to global climate 1 .Previously, it has been shown that, when detected in marine sediments, a C 25 isoprenoid lipid (IP 25 ) biosynthesized by Arctic sea-ice diatoms acts as a proxy for previous spring sea-ice occurrence and subsequent melt 6,7 , whereas the phytoplanktonderived sterol brassicasterol, reflects open-ocean conditions during summer 8 . In the current study, we present organic carbon 9 (global productivity and terrigenous organic carbon input) and fluxes of IP 25 (sea ice) and brassicasterol (phytoplankton; ref. 9) for a sediment core (PS2837-5) from the western flank of the Yermak Plateau (81 • 13.99 N, 02 • 22.85 E, northwest of Spitsbergen, 1,042 m water depth; ref. 10) close to the present-day summer sea-ice margin in Fram Strait (Fig. 1). We use the previously reported age model of PS2837-5, which is based on 14 accelerator mass spectrometry 14 C ages of tests of the planktic foraminifer Neogloboquadrina pachyderma sin. and assumes a marine-reservoir correction of 400 years and linear interpolation between 14 C-dated horizons 11 . In the following, ages are given in calibrated calendar years before present. For much of the interval between 30 and 17 kyr bp (La...

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“…Shemesh et al (2001) suggest that the recorded 3.5‰ Holocene depletion trend reflects an enhanced influence of the isotopically more negative Arctic polar continental air mass. The mean sea-level pressure and surface-wind reconstruction in the early Holocene indeed shows enhanced transport of Atlantic moisture supply to northern Fennoscandia (zonal airflow) (Hebbeln et al, 1994;Hald and Aspeli, 1997). It is likely that when the high pressure system weakened after deglaciation, the Arctic polar continental air mass could penetrate more southward (meridional airflow), and increase the contribution of the Arctic moisture to northern Fennoscandia (Shemesh et al, 2001).…”

Section: Holocene Long-term Trendmentioning

confidence: 99%

Reconstructing past atmospheric circulation changes using oxygen isotopes in lake sediments from Sweden

et al. 2010

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Abstract. Here we use lake sediment studies from Sweden to illustrate how Holocene-aged oxygen isotope records from lakes located in different hydrological settings, can provide information about climate change. In particular changes in precipitation, atmospheric circulation and water balance. We highlight the importance of understanding the present lake hydrology, and the relationship between climate variables and the oxygen isotopic composition of precipitation (δ 18 O p ) and lake waters (δ 18 O lakewater ) for interpretation of the oxygen isotopic record from the sediments (δ 18 O). Both precipitation reconstructions from Northern Sweden and water balance reconstructions from South and Central Sweden show that the atmospheric circulation changed from zonal to a more meridional airflow over the Holocene. Superimposed on this Holocene trend are δ 18 O p minima resembling intervals of the negative phase of the North Atlantic Oscillation (NAO), thus suggesting that the climate of Northern Europe is strongly influenced by atmospheric and oceanic circulation changes over the North Atlantic.

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Moisture supply for northern ice-sheet growth during the Last Glacial Maximum

Cited by 250 publications

References 28 publications

A multiproxy approach to reconstruct the environmental changes along the Eurasian continental margin over the last 150 000 years

A multiproxy approach to reconstruct the environmental changes along the Eurasian continental margin over the last 150 000 years

Variability of sea-ice conditions in the Fram Strait over the past 30,000 years

Reconstructing past atmospheric circulation changes using oxygen isotopes in lake sediments from Sweden

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