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2. Dynamic behaviour of the East Antarctic ice sheet during Pliocene warmth

Author

Cook, CP, Van De Flierdt, T, Williams, T, Hemming, SR, Iwai, M, Kobayashi, M, Jimenez-Espejo, FJ, Escutia, C, González, JJ, Khim, BK, McKay, RM, Passchier, S, Bohaty, SM, Riesselman, CR, Tauxe, L, Sugisaki, S, Galindo, AL, Patterson, MO, Sangiorgi, F, Pierce, EL, Brinkhuis, H, Klaus, A, Fehr, A, Bendle, JAP, Bijl, PK, Carr, SA, Dunbar, RB, Flores, JA, Hayden, TG, Katsuki, K, Kong, GS, Nakai, M, Olney, MP, Pekar, SF, Pross, J, Röhl, U, Sakai, T, Shrivastava, PK, Stickley, CE, Tuo, S, Welsh, K, and Yamane, M

Abstract

Warm intervals within the Pliocene epoch (5.33-2.58 million years ago) were characterized by global temperatures comparable to those predicted for the end of this century and atmospheric CO 2 concentrations similar to today. Estimates for global sea level highstands during these times imply possible retreat of the East Antarctic ice sheet, but ice-proximal evidence from the Antarctic margin is scarce. Here we present new data from Pliocene marine sediments recovered offshore of Adélie Land, East Antarctica, that reveal dynamic behaviour of the East Antarctic ice sheet in the vicinity of the low-lying Wilkes Subglacial Basin during times of past climatic warmth. Sedimentary sequences deposited between 5.3 and 3.3 million years ago indicate increases in Southern Ocean surface water productivity, associated with elevated circum-Antarctic temperatures. The geochemical provenance of detrital material deposited during these warm intervals suggests active erosion of continental bedrock from within the Wilkes Subglacial Basin, an area today buried beneath the East Antarctic ice sheet. We interpret this erosion to be associated with retreat of the ice sheet margin several hundreds of kilometres inland and conclude that the East Antarctic ice sheet was sensitive to climatic warmth during the Pliocene. © 2013 Macmillan Publishers Limited. All rights reserved.

Published
2013

3. Warm and wet conditions in the Arctic region during Eocene Thermal Maximum 2

Author

Sluijs, A., Schouten, S., Donders, T.H., Schoon, P.L., Röhl, U., Reichart, G.-J., Sangiorgi, F., Kim, J.-H., Sinninghe Damste, J.S., Brinkhuis, H., Moleculaire biogeologie, Molecular palaeontology of marine sediments, Palaeoecology, Dep Biologie, Organic geochemistry, Geochemistry, and Sub Palaeoecology begr. 01-01-12

Subjects
Eocene Thermal Maximum 2, Oceanography, Taverne, Global warming, Paleoclimatology, Geowetenschappen en aanverwante (milieu)wetenschappen, General Earth and Planetary Sciences, myr, Climate change, Photic zone, Hydrography, Surface water, Geology
Abstract

Several episodes of abrupt and transient warming, each lasting between 50,000 and 200,000 years, punctuated the long-term warming during the Late Palaeocene and Early Eocene (58 to 51 Myr ago) epochs1,2. These hyperthermal events, such as the Eocene Thermal Maximum 2 (EMT2) that took place about 53.5 Myr ago2, are associated with rapid increases in atmospheric CO2 content. However, the impacts of most events are documented only locally86. Here we show, on the basis of estimates from the TEX 86 ′ proxy, that sea surface temperatures rose by 3-5 C in the Arctic Ocean during the EMT2. Dinoflagellate fossils demonstrate a concomitant freshening and eutrophication of surface waters, which resulted in euxinia in the photic zone. The presence of palm pollen implies5 that coldest month mean temperatures over the Arctic land masses were no less than 8 C, in contradiction of model simulations that suggest hyperthermal winter temperatures were below freezing6. In light of our reconstructed temperature and hydrologic trends, we conclude that the temperature and hydrographic responses to abruptly increased atmospheric CO2 concentrations were similar for the ETM2 and the better-described Palaeocene-Eocene Thermal Maximum7,8, 55.5 Myr ago. © 2009 Macmillan Publishers Limited. All rights reserved.

Published
2009
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