一項(xiàng)研究認(rèn)為,，北極最大的現(xiàn)存冰架在過去10年中的崩潰不太可能是一個沒有先例的事件。
人們把21世紀(jì)初Ward Hunt冰架的瓦解與近來北極的氣候變暖聯(lián)系了起來,。這個冰架是在加拿大Ellesmere島北部面積超過400平方公里的大塊物質(zhì),。
為了確定這個冰架崩潰以及隨之而來的北極冰的損失是否反映了超出自然變動范圍之外的環(huán)境狀況，Dermot Antoniades及其同事分析了來自Disraeli峽灣的沉積物巖芯的特征,，它的漲落狀態(tài)反應(yīng)了位于Disraeli峽灣出口處的這個冰架的狀態(tài),，然后重建了在地質(zhì)時間尺度上這個冰架的積累和崩潰。
這組作者提出,，Ward Hunt冰架很可能是在不早于4000年前形成的,，在大約1400年前斷裂之前穩(wěn)定存在了將近3000年。
這組作者提出,，然后這個冰架很可能在800年前重新形成,，但是在20世紀(jì)末上升的溫度把這個冰架減少到了如今的小尺寸，并且讓由它產(chǎn)生的一個湖干涸了,。這組作者說,，這些發(fā)現(xiàn)是向建立一個長期背景邁出的一步,，有了這個背景，就可以評估目前北極冰的損失,。(生物谷 Bioon.com)
doi:10.1073/pnas.1106378108
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Holocene dynamics of the Arctic's largest ice shelf
Dermot Antoniades, Pierre Francus, Reinhard Pienitz, Guillaume St-Onge, and Warwick F. Vincent
Ice shelves in the Arctic lost more than 90% of their total surface area during the 20th century and are continuing to disintegrate rapidly. The significance of these changes, however, is obscured by the poorly constrained ontogeny of Arctic ice shelves. Here we use the sedimentary record behind the largest remaining ice shelf in the Arctic, the Ward Hunt Ice Shelf (Ellesmere Island, Canada), to establish a long-term context in which to evaluate recent ice-shelf deterioration. Multiproxy analysis of sediment cores revealed pronounced biological and geochemical changes in Disraeli Fiord in response to the formation of the Ward Hunt Ice Shelf and its fluctuations through time. Our results show that the ice shelf was absent during the early Holocene and formed 4,000 years ago in response to climate cooling. Paleoecological data then indicate that the Ward Hunt Ice Shelf remained stable for almost three millennia before a major fracturing event that occurred ∼1,400 years ago. After reformation ∼800 years ago, freshwater was a constant feature of Disraeli Fiord until the catastrophic drainage of its epishelf lake in the early 21st century.
