Acceleration of Northern Ice Sheet Melt Induces AMOC Slowdown and Northern Cooling in Simulations of the Early Last Deglaciation
Acceleration of Northern Ice Sheet Melt Induces AMOC Slowdown and Northern Cooling in Simulations of the Early Last Deglaciation
复制标题
DOI：
10.1029/2017pa003308
复制
发表时间：
2018-07
影响因子：
3.5
通讯作者：
R. Ivanović;L. Gregoire;Andrea Burke;A. Wickert;Paul J. Valdes;H. C. Ng;Laura F. Robinson;Jerry F. McManus;J. Mitrovica;Lindsay Lee;J. Dentith
中科院分区：
文献类型：
--
作者：
R. Ivanović;L. Gregoire;Andrea Burke;A. Wickert;Paul J. Valdes;H. C. Ng;Laura F. Robinson;Jerry F. McManus;J. Mitrovica;Lindsay Lee;J. Dentith
海因里希阶梯1~18.5ka开始时，大西洋环流和北半球冷却的快速变化的原因尚不清楚。以前的研究使用冰盖和/或冰山融水强迫来模拟这一事件，但这些理想化的淡水通量一直是不切实际的大。在这里，我们使用一种不同的方法，通过最近时间分辨的全球古冰盖重建来驱动高分辨率的水系网络模型，以产生真实的融水强迫。我们将这一通量输入Hadley中心耦合模式第3版(HadCM3)气候模式，不调整时间或幅度，发现北部冰盖融化的加速(高达~7.5m/Kyr全球平均海平面上升当量)触发了大西洋经向翻转环流减少20%。模拟的海洋环流和气候变化模式与海因里希阶梯1号开始时的一系列古气候和海洋环流重建相匹配，无论是变化的速度还是程度。这是通过与海平面变化和冰盖演化的限制相匹配的融水通量来实现的，大约19-18ka。由于融化速度与格陵兰岛预计到2200年的融化速度相似，限制海因里希阶梯1期间的融化速度和气候变化的幅度将对气候模型对未来冰盖融化的敏感性进行重要测试。
The cause of a rapid change in Atlantic Ocean circulation and northern cooling at the onset of Heinrich Stadial 1 ~18.5 ka is unclear. Previous studies have simulated the event using ice sheet and/or iceberg meltwater forcing, but these idealized freshwater fluxes have been unrealistically large. Here we use a different approach, driving a high‐resolution drainage network model with a recent time‐resolved global paleo‐ice sheet reconstruction to generate a realistic meltwater forcing. We input this flux to the Hadley Centre Coupled Model version 3 (HadCM3) climate model without adjusting the timing or amplitude and find that an acceleration in northern ice sheet melting (up to ~7.5 m/kyr global mean sea level rise equivalent) triggers a 20% reduction in the Atlantic Meridional Overturning Circulation. The simulated pattern of ocean circulation and climate change matches an array of paleoclimate and ocean circulation reconstructions for the onset of Heinrich Stadial 1, in terms of both rates and magnitude of change. This is achieved with a meltwater flux that matches constraints on sea level changes and ice sheet evolution around 19–18 ka. Since the rates of melting are similar to those projected for Greenland by 2200, constraining the melt rates and magnitude of climate change during Heinrich Stadial 1 would provide an important test of climate model sensitivity to future ice sheet melt.