英國科學家在最新一期《自然·地球科學》雜志上發(fā)表論文稱,，過去一直認為相對穩(wěn)定的南極東部冰原實際上十分脆弱,，500萬年前的全球氣候變暖曾造成這部分冰原大面積融化,，使得海平面上升了將近10米,。
為了解古代南極東部冰原的融冰情況,，倫敦帝國理工學院的研究人員對取自于南極東部海岸水下3000米海底的泥漿樣本進行了化學成分分析,。分析結果表明，形成這些泥漿的巖石存在于東部冰原之中,，只有冰原融化縮小,，這些巖石才會受到侵蝕，進而沉積到海底形成泥漿。而在距今300萬年到500萬年前,，即稱為上新世的地質時期,，全球氣候變暖使得南極東部冰原出現大量融冰，融冰量可使海平面上升近10米,。在同一時期,，南極西部以及格陵蘭島的部分冰原也因氣候變暖而融化。研究人員推測,，這一時期全球融冰造成海平面上升了大約20米,。
南極東部冰原形成于3400萬年前，是地球上最大的冰原,，其面積與澳大利亞差不多大小,。科學家們過去一直認為,，南極東部冰原比南極西部冰原和格陵蘭島冰原都要穩(wěn)定,，但新研究表明，南極東部冰原對于氣候變化的敏感程度比科學家原來預想的要大得多,。
研究人員指出,，在上新世時期，地球大氣中二氧化碳的濃度與今天十分相似,，而有科學家預計,，到本世紀末，全球氣溫也會與上新世時期的地球溫度大體一致,。因此,，了解上新世冰川的融化情況有助于研究如今全球變暖對海平面波動的影響，這對于全面理解氣候變化對地球環(huán)境的影響十分重要,。（生物谷 Bioon.com）
生物谷推薦的英文摘要
Nature Geoscience doi:10.1038/ngeo1889
Dynamic behaviour of the East Antarctic ice sheet during Pliocene warmth
Carys P. Cook, Tina van de Flierdt, Trevor Williams, Sidney R. Hemming, Masao Iwai, Munemasa Kobayashi, Francisco J. Jimenez-Espejo, Carlota Escutia, Jhon Jairo González, Boo-Keun Khim, Robert M. McKay, Sandra Passchier, Steven M. Bohaty, Christina R. Riesselman, Lisa Tauxe, Saiko Sugisaki, Alberto Lopez Galindo, Molly O. Patterson, Francesca Sangiorgi, Elizabeth L. Pierce, Henk Brinkhuis, Adam Klaus, Annick Fehr, James A. P. Bendle, Peter K. Bijl, Stephanie A. Carr, Robert B. Dunbar, José Abel Flores, Travis G. Hayden, Kota Katsuki, Gee Soo Kong, Mutsumi Nakai, Matthew P. Olney, Stephen F. Pekar, Jörg Pross, Ursula Röhl, Toyosaburo Sakai, Prakash K. Shrivastava, Catherine E. Stickley, Shouting Tuo, Kevin Welsh & Masako Yamane
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 century1 and atmospheric CO2 concentrations similar to today2, 3, 4. Estimates for global sea level highstands during these times5 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.
