Why there was not a Younger Dryas-like event during the Penultimate Deglaciation
Why there was not a Younger Dryas-like event during the Penultimate Deglaciation
复制标题
DOI：
10.1016/j.quascirev.2008.02.004
复制
发表时间：
2008-05-01
影响因子：
4
通讯作者：
Carlson, Anders E.
中科院分区：
文献类型：
--
作者：
Carlson, Anders E.
与之前的冰川消融相比，新仙女木时期的寒冷事件是最后一次冰川消融的一个相对独特的特征，表明这是一个独特的触发因素，而不是通常认为的北美淡水流向北大西洋的强迫机制。在这里，我比较了最后一次（T-I）和第二次（T-II）冰川消融，并为以下论点提供了新的支持：在第二次（T-II）期间没有发生类似年轻干旱的事件是由于北半球冰盖在北方夏季更强的日照强迫下迅速退缩。加速的冰退缩抑制了大西洋经向翻转环流（AMOC），直到接近T-II结束，而在T-II期间AMOC增加相对较早。在T-I期间，引起新仙女木期的淡水东移发生在AMOC恢复之后，而在T-II期间，这种东移发生在AMOC恢复之前。因此，T-II期间北大西洋淡水流量的增加对AMOC的影响很小，这就解释了为什么在这次消冰期间没有出现类似新干旱期的气候振荡。(C) 2008 Elsevier Ltd版权所有。
The Younger Dryas cold event is a relatively unique feature of the last deglaciation when compared to previous deglaciations, suggesting a unique trigger rather than the commonly held forcing mechanism of North American freshwater routing to the North Atlantic. Here, I compare the last (T-I) and penultimate (T-II) deglaciations and provide new support for the argument that the lack of a Younger Dryas-like event during T-II is due to the rapidity of Northern Hemisphere ice sheet retreat under greater boreal summer insolation forcing. Faster ice retreat suppressed Atlantic meridional overturning circulation (AMOC) until near the end of T-II, while during T-I AMOC increased relatively early. During T-I, the eastward routing of freshwater that caused the Younger Dryas happened after AMOC resumption, whereas during T-II this routing occurred prior to the resumption of AMOC. Thus the increased flux of freshwater to the North Atlantic during T-II had little effect on AMOC, explaining the lack of a Younger Dryas-like climate oscillation during this deglaciation. (C) 2008 Elsevier Ltd. All rights reserved.