Stratification-induced variations in nutrient utilization in the Polar North Atlantic during past interglacials
Stratification-induced variations in nutrient utilization in the Polar North Atlantic during past interglacials
复制标题
过去间冰期期间北大西洋极地分层引起的养分利用变化
DOI：
10.1016/j.epsl.2016.09.060
复制
发表时间：
2016
影响因子：
5.3
通讯作者：
Pedersen T.F.
中科院分区：
文献类型：
--
作者：
Thibodeau B;Bauch H.A;Pedersen T.F.
极地北大西洋的垂直水团结构通过影响北大西洋深水的形成速率对行星气候起着关键作用，而北大西洋深水的形成又影响北半球的表面热传递、深海的通风和全球海洋环流。然而，由于全球气温上升和格陵兰冰川消融导致的地表水变暖和淡水增加，北欧海域上层层化对近期水文强迫的反应仍然鲜为人知。虽然过去的主要间冰期被视为与现在的潜在类似物，但最近的研究结果表明，与全新世相比，极地北大西洋在海洋同位素阶段5e和11期间的表层海洋状况非常不同。因此，至关重要的是要查明这些差异的原因，以便了解它们在气候和海洋变化中的作用。为了解决这个问题，我们在这里将块状沉积物δ15N同位素特征与过去主要间冰期的浮游有孔虫组合及其同位素组成配对。这一比较首次确定了层化引起的硝酸盐利用在所有这些暖期之间和之内的变化高达25%，这突显了之前整个间冰期混合层厚度的变化。这一厚度直接控制着大西洋水流入的深度。因此，这里记录的硝酸盐利用的主要变化表明，在过去的间冰期，盛行着较厚的混合层，可能与之前冰川终止相关的较长时间的淡水输入有关。这将导致大西洋水在MIS5e和MIS11期间在更深的地方流动。这些结果呼吁在使用较老的间冰期作为现代或近期气候模拟时保持谨慎，并有助于提高我们对北欧海等全球重要深水形成地点附近淡水输入影响的总体理解。在评估气候变化和全球变暖对格陵兰冰盖的负面影响时，这一点至关重要。
Vertical water mass structure in the Polar North Atlantic Ocean plays a critical role in planetary climate by influencing the formation rate of North Atlantic deepwater, which in turn affects surface heat transfer in the northern hemisphere, ventilation of the deep sea, and ocean circulation on a global scale. However, the response of upper stratification in the Nordic seas to near-future hydrologic forcing, as surface water warms and freshens due to global temperature rise and Greenland ice demise, remains poorly known. While past major interglacials are viewed as potential analogues of the present, recent findings suggest that very different surface ocean conditions prevailed in the Polar North Atlantic during Marine Isotope Stage (MIS) 5e and 11 compared to the Holocene. It is thus crucial to identify the causes of those differences in order to understand their role in climatic and oceanographic variability. To resolve this, we pair here bulk sedimentδ15N isotopic signatures with planktonic foraminiferal assemblages and their isotopic composition across major past interglacials. The comparison defines for the first time stratification-induced variations in nitrate utilization up to 25% between and within all of these warm periods that highlight changes in the thickness of the mixed-layer throughout the previous interglacials. That thickness directly controls the depth-level of Atlantic water inflow. The major changes of nitrate utilization recorded here thus suggest that a thicker mixed-layer prevailed during past interglacials, probably related to longer freshwater input associated with the preceding glacial termination. This would have caused the Atlantic water to flow at greater depth during MIS 5e and 11. These results call for caution when using older interglacials as modern or near-future climate analogues and contribute to the improvement of our general comprehension of the impact of freshwater input near a globally important deep-water formation site like the Nordic Seas. This is crucial when assessing the negative impacts on the Greenland Ice Sheet of climate change and global warming.
登录
查看更多内容
影响因子：
56.9
作者：
J. Lynch‐Stieglitz;J. Adkins;W. Curry;T. Dokken;I. Hall;J. Herguera;J. Hirschi;E. Ivanova;
通讯作者：
J. Lynch‐Stieglitz;J. Adkins;W. Curry;T. Dokken;I. Hall;J. Herguera;J. Hirschi;E. Ivanova;
影响因子：
--
作者：
Bauch, Henning A.;Kandiano, Evguenia S.
通讯作者：
Kandiano, Evguenia S.
根据海面浮力通量诊断北欧海域的浓水形成
DOI：
--
发表时间：
2007
期刊：
影响因子：
--
作者：
P. Isachsen;C. Mauritzen;H. Svendsen
通讯作者：
H. Svendsen
MIS 5e（埃米安间冰期）期间北欧海面的晚期变暖和早期冷却
影响因子：
4
作者：
T. L. Rasmussen;E. Thomsen;A. Kuijpers;S. Wastegård
通讯作者：
S. Wastegård
基于甲藻包囊的沃尔令高原（挪威海）末次间冰期 (MIS 5e) 地表水状况
影响因子：
1.9
作者：
Nicolas Van Nieuwenhove;H. Bauch
通讯作者：
H. Bauch