Deglacial rapid sea level rises caused by ice-sheet saddle collapses
Deglacial rapid sea level rises caused by ice-sheet saddle collapses
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DOI：
10.1038/nature11257
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发表时间：
2012-07-12
期刊：
影响因子：
64.8
通讯作者：
Valdes, Paul J.
中科院分区：
文献类型：
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作者：
Gregoire, Lauren J.;Payne, Antony J.;Valdes, Paul J.
最后一次消冰（21000至7000年前）被几次突然的融水脉冲打断，有时引起明显的气候变化（1,2）。大约在1.4万年前，其中最大的一次融水脉冲1A （MWP-1A）在350年的时间里使海平面上升了14-18米(3)。虽然这种巨大的水波肯定是由冰盖的退缩引起的，但对于地理来源或控制海平面快速上升的潜在物理机制，人们并没有达成共识（4-6）。在这里，我们提出了一个冰盖模型模拟，其中北美劳伦泰德冰盖和科迪勒兰冰盖的分离产生了一个与MWP-1A相对应的融水脉冲。当拉布拉多冰和巴芬冰在哈德逊湾周围分离时，会产生另一个融水脉冲，这可能与“8200年”事件有关，这是过去九千年来最明显的气候突变事件(7)。在这两个模拟脉冲中，由于气候变暖导致的普遍地表下降，两个冰穹之间的鞍状物会受到地表融化的影响。随着两个圆顶之间的鞍形结构降低，融化速度迅速加快，在500年的时间里，海平面上升了9米。这种冰“马鞍崩塌”的机制可能解释了MWP-1A和8200年的事件，并揭示了这些事件对气候的影响。
The last deglaciation (21 to 7 thousand years ago) was punctuated by several abrupt meltwater pulses, which sometimes caused noticeable climate change(1,2). Around 14 thousand years ago, meltwater pulse 1A (MWP-1A), the largest of these events, produced a sea level rise of 14-18 metres over 350 years(3). Although this enormous surge of water certainly originated from retreating ice sheets, there is no consensus on the geographical source or underlying physical mechanisms governing the rapid sea level rise(4-6). Here we present an ice-sheet modelling simulation in which the separation of the Laurentide and Cordilleran ice sheets in North America produces a meltwater pulse corresponding to MWP-1A. Another meltwater pulse is produced when the Labrador and Baffin ice domes around Hudson Bay separate, which could be associated with the '8,200-year' event, the most pronounced abrupt climate event of the past nine thousand years(7). For both modelled pulses, the saddle between the two ice domes becomes subject to surface melting because of a general surface lowering caused by climate warming. The melting then rapidly accelerates as the saddle between the two domes gets lower, producing nine metres of sea level rise over 500 years. This mechanism of an ice 'saddle collapse' probably explains MWP-1A and the 8,200-year event and sheds light on the consequences of these events on climate.