Evolving conditions at the terminus of Thwaites Glacier will be important in determining the rate of its future sea-level contribution over the coming decades. Here, we use remote-sensing observations to investigate recent changes (2000–2018) in the structure and velocity of Thwaites Glacier and its floating tongue. We show that the main trunk of Thwaites Glacier has accelerated by 38% over this period, while its previously intact floating tongue has transitioned to a weaker mélange of fractured icebergs bounded by sea ice. However, the rate of structural weakening and acceleration was not uniform across the observational period and we identify two periods of rapid acceleration and structural weakening (2006–2012; 2016–2018), separated by a period of deceleration and re-advance of the structurally-intact shear margin boundary (2012–2015). The timing of these accelerations/decelerations strongly suggests a link to variable ocean forcing. The weakened tongue now has some dependency on landfast sea ice for structural integrity and is vulnerable to changes in landfast ice persistency. Future reductions in landfast sea ice could manifest from changes in climate and/or the imminent removal of the B-22A iceberg from the Thwaites embayment. Such changes could have important implications for the integrity of the ice tongue and future glacier discharge.

中文翻译：

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2000 年至 2018 年间，思韦茨冰川舌的间歇性结构减弱和加速

Thwaites Glacier 终点的不断变化的条件对于确定其未来几十年对海平面的贡献率非常重要。在这里，我们使用遥感观测来调查 Thwaites Glacier 及其浮舌的结构和速度的近期变化（2000-2018 年）。我们表明，Thwaites Glacier 的主干在此期间加速了 38%，而其之前完整的浮舌已转变为以海冰为界的较弱的断裂冰山混合体。然而，在整个观测期间，结构弱化和加速的速率并不均匀，我们确定了两个快速加速和结构弱化的时期（2006-2012；2016-2018），由结构减速和重新推进的时期分隔。 -完整的剪切边缘边界（2012-2015）。这些加速/减速的时间强烈表明与可变海洋强迫有关。减弱的舌头现在在结构完整性方面对陆上海冰有一定的依赖性，并且容易受到陆上冰持久性变化的影响。未来陆上海冰的减少可能体现在气候变化和/或 B-22A 冰山即将从 Thwaites 海湾移除。这种变化可能对冰舌的完整性和未来的冰川排放产生重要影响。未来陆上海冰的减少可能体现在气候变化和/或 B-22A 冰山即将从 Thwaites 海湾移除。这种变化可能对冰舌的完整性和未来的冰川排放产生重要影响。未来陆上海冰的减少可能体现在气候变化和/或 B-22A 冰山即将从 Thwaites 海湾移除。这种变化可能对冰舌的完整性和未来的冰川排放产生重要影响。