Benn Douglas I, Cowton Tom, Todd Joe, Luckman Adrian
1School of Geography and Sustainable Development, University of St Andrews, St Andrews, KY16 9AL UK.
2Department of Geography, Swansea University, Swansea, SA2 8PP UK.
Curr Clim Change Rep. 2017;3(4):282-290. doi: 10.1007/s40641-017-0070-1. Epub 2017 Oct 27.
In combination, the breakaway of icebergs (calving) and submarine melting at marine-terminating glaciers account for between one third and one half of the mass annually discharged from the Greenland Ice Sheet into the ocean. These ice losses are increasing due to glacier acceleration and retreat, largely in response to increased heat flux from the oceans. Behaviour of Greenland's marine-terminating ('tidewater') glaciers is strongly influenced by fjord bathymetry, particularly the presence of 'pinning points' (narrow or shallow parts of fjords that encourage stability) and over-deepened basins (that encourage rapid retreat). Despite the importance of calving and submarine melting and significant advances in monitoring and understanding key processes, it is not yet possible to predict the tidewater glacier response to climatic and oceanic forcing with any confidence. The simple calving laws required for ice-sheet models do not adequately represent the complexity of calving processes. New detailed process models, however, are increasing our understanding of the key processes and are guiding the design of improved calving laws. There is thus some prospect of reaching the elusive goal of accurately predicting future tidewater glacier behaviour and associated rates of sea-level rise.
综合来看，海洋末端冰川的冰山崩解（裂冰作用）和海底融化占格陵兰冰盖每年排入海洋质量的三分之一到二分之一。由于冰川加速和后退，这些冰损失正在增加，这在很大程度上是对海洋热通量增加的响应。格陵兰海洋末端（“潮汐”）冰川的行为受到峡湾水深测量的强烈影响，特别是“固定点”（鼓励冰川稳定的峡湾狭窄或浅的部分）和过度加深的盆地（鼓励冰川快速后退）的存在。尽管裂冰作用和海底融化很重要，并且在监测和理解关键过程方面取得了重大进展，但目前仍无法自信地预测潮汐冰川对气候和海洋强迫的响应。冰盖模型所需的简单裂冰定律不能充分体现裂冰过程的复杂性。然而，新的详细过程模型正在增进我们对关键过程的理解，并指导改进裂冰定律的设计。因此，有一定的前景实现准确预测未来潮汐冰川行为及相关海平面上升速率这一难以实现的目标。
