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The role of an Arctic ice shelf in the climate of the last glacial maximum of MIS 6 (140 ka)
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper. Joseph Fourier University, France.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
2010 (engelsk)Inngår i: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 29, nr 25-26, s. 3590-3597Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

During the last decade, Arctic icebreaker and nuclear submarine expeditions have revealed large-scale Pleistocene glacial erosion on the Lomonosov Ridge, Chukchi Borderland and along the Northern Alaskan margin indicating that the glacial Arctic Ocean hosted large Antarctic-style ice shelves. Dating of sediment cores indicates that the most extensive and deepest ice grounding occurred during Marine Isotope Stage (MIS) 6. The precise extents of Pleistocene ice shelves in the Arctic Ocean are unknown but seem comparable to present existing Antarctic ice shelves. How would an Antarctic-style ice shelf in the MIS 6 Arctic Ocean influence the Northern Hemisphere climate? Could it have impacted on the surface mass balance (SMB) of the MIS 6 Eurasian ice sheet and contributed to its large southward extent? We use an Atmospheric General Circulation Model (AGCM) to investigate the climatic impacts of both a limited MIS 6 ice shelf covering portions of the Canada Basin and a fully ice shelf covered Arctic Ocean. The AGCM results show that both ice shelves cause a temperature cooling of about 3 °C over the Arctic Ocean mainly due to the combined effect of ice elevation and isolation from the underlying ocean heat fluxes stopping the snow cover from melting during summer. The calculated SMB of the ice shelves are positive. The ice front horizontal velocity of the Canada Basin ice shelf is estimated to ≈ 1 km yr−1 which is comparable to the recent measurements of the Ross ice shelf, Antarctica. The existence of a large continuous ice shelf covering the entire Arctic Ocean would imply a mean annual velocity of icebergs of ≈12 km yr−1 through the Fram Strait. Our modeling results show that both ice shelf configurations could be viable under the MIS 6 climatic conditions. However, the cooling caused by these ice shelves only affects the Arctic margins of the continental ice sheets and is not strong enough to significantly influence the surface mass balance of the entire MIS 6 Eurasian ice sheet.

sted, utgiver, år, opplag, sider
2010. Vol. 29, nr 25-26, s. 3590-3597
Emneord [en]
Arctic ice shelf, Marine Isotope Stage 6, atmospheric modeling, climate
HSV kategori
Identifikatorer
URN: urn:nbn:se:su:diva-29301DOI: 10.1016/j.quascirev.2010.06.023ISI: 000284724400018OAI: oai:DiVA.org:su-29301DiVA, id: diva2:232271
Tilgjengelig fra: 2009-08-21 Laget: 2009-08-20 Sist oppdatert: 2017-12-13bibliografisk kontrollert
Inngår i avhandling
1. On the Late Saalian glaciation: A climate modeling study
Åpne denne publikasjonen i ny fane eller vindu >>On the Late Saalian glaciation: A climate modeling study
2009 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis focuses on the glaciation of the Late Saalian period (160 -140 ka) over Eurasia. The Quaternary Environment of the Eurasian North (QUEEN) project determined that during this period, the Eurasian ice sheet was substantially larger than during the entire Weichselian cycle and especially that of the Last Glacial Maximum (21 ka, LGM). The Late Saalian astronomical forcing was different than during the LGM while greenhouse gas concentrations were similar. To understand how this ice sheet could have grown so large over Eurasia during the Late Saalian, we use an Atmospherical General Circulation Model (AGCM) coupled to an oceanic mixed layer and a vegetation model to explore the influence of regional parameters, sea surface temperatures (SST) and orbital parameters on the surface mass balance (SMB) of the Late Saalian Eurasian ice sheet.

At140 ka, proglacial lakes, vegetation and simulated Late Saalian SST cool the Eurasian climate, which reduce the ablation along the southern ice sheet margins. Dust deposition on snow has the opposite effect. The presence of a Canada Basin ice-shelf during MIS6 in the Arctic Ocean, does not affect the mass balance of the ice sheet. According to geological evidence, the Late Saalian Eurasian ice sheet reached its maximum extent before 160 ka. Northern Hemisphere high latitude summer insolation shows a large insolation peak near 150 ka. The simulated climate prior to 140 ka is milder and ablation is larger along the southern margins of the Eurasian ice sheet although the mean annual SMB is positive. The Late Saalian Eurasian ice sheet may have been large enough to generate its own cooling, thus maintaining itself over Eurasia. 

sted, utgiver, år, opplag, sider
Stockholm: Department of Geology and Geochemistry, Stockholm University, 2009. s. 53
Serie
Meddelanden från Stockholms universitets institution för geologi och geokemi, ISSN 1101-1599 ; 335
Emneord
Climate modeling, Eurasian ice sheet, Quaternary, Saalian, surface mass balance, SST
HSV kategori
Forskningsprogram
marin geovetenskap
Identifikatorer
urn:nbn:se:su:diva-29284 (URN)978-91-7155-914-2 (ISBN)
Disputas
2009-09-14, Laboratoire de Glaciologie et Géophysique de l'Environnement, Université Joseph Fourier, 54 rue Moliére, St-Martin d'Héres Cedex, France, 10:00 (engelsk)
Opponent
Veileder
Merknad
Joint PhD Degree between Stockholm University and Université Joseph Fourier At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Submitted. Paper 5: Manuscript.Tilgjengelig fra: 2009-08-30 Laget: 2009-08-20 Sist oppdatert: 2009-08-21bibliografisk kontrollert

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