Sliding at the base Predictions of sea level rise caused by dynamic ice sheet loss rely on a good understanding of what controls how fast the sheets slide over the ground below. The standard approach is to model motion on the basis of an assumed frictional stress between the base of the glacier and a hard underlying bed. Now, however, Stearns and van der Veen show that this method is incorrect. Instead, they suggest that net pressure at the glacier bed controls flow. Science, this issue p. 273 The sliding speed of ice streams is controlled by net pressure at the glacier bed. The largest uncertainty in the ice sheet models used to predict future sea level rise originates from our limited understanding of processes at the ice/bed interface. Near glacier termini, where basal sliding controls ice flow, most predictive ice sheet models use a parameterization of sliding that has been theoretically derived for glacier flow over a hard bed. We find that this sliding relation does not apply to the 140 Greenland glaciers that we analyzed. There is no relationship between basal sliding and frictional stress at the glacier bed, contrary to theoretical predictions. There is a strong relationship between sliding speed and net pressure at the glacier bed. This latter finding is in agreement with earlier observations of mountain glaciers that have been largely overlooked by the glaciological community.

中文翻译：

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床层的摩擦无法控制冰川的快速流动

在底部滑动 由动态冰盖损失引起的海平面上升的预测依赖于对控制冰盖在下方地面滑动速度的因素的充分理解。标准方法是根据冰川底部和硬底床之间假定的摩擦应力对运动进行建模。然而，现在 Stearns 和 van der Veen 表明这种方法是不正确的。相反，他们建议冰川床的净压力控制流量。科学，这个问题 p。273 冰流的滑动速度由冰川床的净压力控制。用于预测未来海平面上升的冰盖模型中最大的不确定性源于我们对冰/床界面过程的有限了解。在冰川终点附近，基底滑动控制冰流，大多数预测性冰盖模型使用的滑动参数化是从理论上推导出硬床冰川流的参数化。我们发现这种滑动关系不适用于我们分析的 140 条格陵兰冰川。与理论预测相反，冰川床的基底滑动和摩擦应力之间没有关系。冰川床的滑动速度和净压力之间有很强的关系。后一个发现与先前对冰川学界在很大程度上忽视的山地冰川的观察结果一致。与理论预测相反，冰川床的基底滑动和摩擦应力之间没有关系。冰川床的滑动速度和净压力之间有很强的关系。后一个发现与先前对冰川学界在很大程度上忽视的山地冰川的观察结果一致。与理论预测相反，冰川床的基底滑动和摩擦应力之间没有关系。冰川床的滑动速度和净压力之间有很强的关系。后一个发现与先前对冰川学界在很大程度上忽视的山地冰川的观察结果一致。