Changes in surface salinity of the North Atlantic Ocean during the last deglaciation
Changes in surface salinity of the North Atlantic Ocean during the last deglaciation
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DOI：
10.1038/358485a0
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发表时间：
1992-08
期刊：
影响因子：
64.8
通讯作者：
J. Duplessy;L. Labeyrie;M. Arnold;M. Paterne;J. Duprat;T. V. Weering
中科院分区：
文献类型：
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作者：
J. Duplessy;L. Labeyrie;M. Arnold;M. Paterne;J. Duprat;T. V. Weering
突然而短暂的气候变化，例如新仙女木期，打破了最后一次冰期到间冰期的转变1-4。 Broecker 等人 5 提出，这些可能是由于冰川融水的输入使北大西洋的地表水变得清新而引起的温盐环流中断所致。然而，新仙女木期融水排放量极少的发现6表明，地表水盐度下降可能是由淡水收支变化（降水与蒸发之间的差异）引起的，同时伴随着副热带咸水向极地平流的减少。在这里，我们使用来自北大西洋两个岩心的有孔虫的微古生物学和稳定同位素记录，生成过去 18,000 年海面温度和盐度变化的两个连续、高分辨率的记录。尽管在温暖时期注入了冰川融水，但我们发现在冰消期期间海面盐度和温度仍然呈正相关。寒冷、低盐度事件发生在冰消作用的早期阶段（14,500-13,000年前）和新仙女木期，但这些事件期间高纬度地区融水的少量注入不足以解释观测到的盐度变化。我们的结论是，水文循环和平流变化的额外反馈对于引发温盐环流的变化以及气候的变化是必要的。当融水注入发生在低纬度时，这种反馈不起作用。
ABRUPT and short climate changes, such as the Younger Dryas, punctuated the last glacial-to-interglacial transition1–4. Broecker et al.5proposed that these may have been caused by an interruption of thermohaline circulation as inputs of glacial meltwater freshened the surface waters of the North Atlantic. The finding6that meltwater discharge was minimal during the Younger Dryas, however, led to the suggestion that the surface-water salinity drop might have been caused instead by changes in the freshwater budget (the difference between precipitation and evaporation), accompanied by a reduction in poleward advection of saline subtropical water. Here we use micropalaeontological and stable-isotope records from foraminifera in two cores from the North Atlantic to generate two continuous, high-resolution records of sea surface temperature and salinity changes over the past 18,000 years. Despite the injection of glacial meltwater during warm episodes, we find that sea surface salinity and temperature remain positively correlated during deglaciation. Cold, low-salinity events occurred during the early stages of deglaciation (14,500–13,000 years ago) and the Younger Dryas, but the minor injections of meltwater at high latitudes during these events are insufficient to account for the observed salinity changes. We conclude that an additional feedback from changes in the hydrological cycle and in advection was necessary to trigger changes in thermohaline circulation and thus in climate. This feedback did not act when the meltwater injection occurred at low latitude.