Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate
Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate
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DOI：
10.5194/tc-9-1579-2015
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发表时间：
2015-01-01
期刊：
影响因子：
5.2
通讯作者：
Vaughan, D. G.
中科院分区：
文献类型：
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作者：
Cornford, S. L.;Martin, D. F.;Vaughan, D. G.
我们使用BISICLES自适应网格冰盖模型对西南极冰盖的快速流动冰流进行了1个、2个和3个世纪的模拟，在接地线周围采用了亚千米分辨率，因为较粗的分辨率会导致对响应的严重低估。每一次模拟都从接近现今观测的几何形状和速度开始，并根据大气降雪冰积累速率和海洋冰架融化速率的变化而演变。积累和融化速率的未来变化范围从无变化，到由厄尔尼诺（El）和A1B排放情景驱动的大气和海洋模型计算出的异常值，再到在几个世纪内消除大部分冰架的空间均匀融化速率异常值。我们发现，尽管冰积累对漂浮面以上体积的净变化影响程度相似，但由此产生的冰动力学变化主要由初始条件、冰架融化速率和网格分辨率的选择所决定。如果有足够的融化速率，我们计算出在每条主要冰流中接地线会后退数百公里，但海洋模型预测在2100年之前，除了阿蒙森海中湾以外不会有这样的融化速率。在阿蒙森海中湾内，最大的单一变化源是思韦茨冰川持续后退的开始，这可能会使海平面均衡上升速率增加两倍。
We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet, deploying sub-kilometer resolution around the grounding line since coarser resolution results in substantial underestimation of the response. Each of the simulations begins with a geometry and velocity close to present-day observations, and evolves according to variation in meteoric ice accumulation rates and oceanic ice shelf melt rates. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the El and A1B emissions scenarios, to spatially uniform melt rate anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions and ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Within the Amundsen Sea Embayment the largest single source of variability is the onset of sustained retreat in Thwaites Glacier, which can triple the rate of eustatic sea level rise.