Modelling global-scale climate impacts of the late Miocene Messinian Salinity Crisis
Modelling global-scale climate impacts of the late Miocene Messinian Salinity Crisis
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DOI：
10.5194/cp-10-607-2014
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发表时间：
2014-01-01
影响因子：
4.3
通讯作者：
Gutjahr, M.
中科院分区：
文献类型：
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作者：
Ivanovic, R. F.;Valdes, P. J.;Gutjahr, M.
中新世晚期地中海-大西洋连通性的构造变化和气候变化导致地中海盐度剧烈波动，包括十倍增加和接近淡化。最近的代理和模型为基础的证据表明，在这个墨西拿盐度危机（MSC，5.96-5.33马），高盐水和高淡水地中海流入北大西洋，而在其他时间，没有地中海流出水（MOW）到达大西洋。通过使用完全耦合的海洋-大气环流模型进行极端敏感型实验，我们研究了这些不同的MSC MOW情景影响全球尺度气候的潜力。模拟表明，尽管影响仍然相对较小，但MOW对北大西洋环流和气候的影响比今天更大。我们还发现，根据MOW的存在，强度和盐度，MSC可能已经能够将北方中高纬度地区冷却几度，最大的冷却发生在拉布拉多，格陵兰岛-冰岛-挪威和巴伦支海。随着高盐MOW，北大西洋深水形成的一个组成部分转移到地中海，加强大西洋经向翻转环流（AMOC）以南35度N的1.5-6西弗。随着低盐MOW，AMOC完全关闭，诱导了北部强冷却的两极气候异常（主要是-1到-3摄氏度，但最高可达-8摄氏度），南部变暖较弱这些模拟确定了未来替代重建的关键目标区域和气候变量，为（a）提供最佳和最可靠的测试案例。评估墨西拿模式的性能，（B）评估地中海-大西洋在MSC期间的连通性，以及（c）确定MSC是否曾经影响过全球尺度的气候。
Late Miocene tectonic changes in Mediterranean-Atlantic connectivity and climatic changes caused Mediterranean salinity to fluctuate dramatically, including a tenfold increase and near-freshening. Recent proxy-and model-based evidence suggests that at times during this Messinian Salinity Crisis (MSC, 5.96-5.33 Ma), highly saline and highly fresh Mediterranean water flowed into the North Atlantic Ocean, whilst at others, no Mediterranean Outflow Water (MOW) reached the Atlantic. By running extreme, sensitivity-type experiments with a fully coupled ocean-atmosphere general circulation model, we investigate the potential of these various MSC MOW scenarios to impact global-scale climate.The simulations suggest that although the effect remains relatively small, MOW had a greater influence on North Atlantic Ocean circulation and climate than it does today. We also find that depending on the presence, strength and salinity of MOW, the MSC could have been capable of cooling mid-high northern latitudes by a few degrees, with the greatest cooling taking place in the Labrador, Greenland-Iceland-Norwegian and Barents seas. With hypersaline MOW, a component of North Atlantic Deep Water formation shifts to the Mediterranean, strengthening the Atlantic Meridional Overturning Circulation (AMOC) south of 35 degrees N by 1.5-6 Sv. With hyposaline MOW, AMOC completely shuts down, inducing a bipolar climate anomaly with strong cooling in the north (mainly -1 to -3 degrees C, but up to -8 degrees C) and weaker warming in the south (up to +0.5 to +2.7 degrees C).These simulations identify key target regions and climate variables for future proxy reconstructions to provide the best and most robust test cases for (a) assessing Messinian model performance, (b) evaluating Mediterranean-Atlantic connectivity during the MSC and (c) establishing whether or not the MSC could ever have affected global-scale climate.