近日，美国加州大学欧文分校Eric Rignot团队报道了南极西部思韦茨冰川接地冰区的融化状态对比。这一研究成果于2025年11月17日发表在《美国科学院院刊》杂志上。

南极思韦茨冰川对海平面上升的贡献程度，主要取决于源自环极深层水的温暖咸海水对其接地线附近底部冰层融化速度的影响。卫星观测显示，在潮汐作用下形成的千米级海水入侵现象会渗入接地冰体下方，形成一个"冰接地带"。该区域内的冰体正经历剧烈融化。尽管通过相位敏感雷达回声探测仪与自主水下航行器等设备已在特定点位测得融化速率，但冰接地带内融化分布的空间格局及总量仍不明确。

研究组采用麻省理工学院全球环流海洋模型，对思韦茨冰川融化机制开展了二维高分辨率模拟。模型预测显示：冰接地带入口处融化最为强烈，向内部呈二次函数衰减；融化速率随海洋热强迫线性增长，随冰下空腔长度呈亚线性增长。在移动缓慢的思韦茨东部冰架，模拟显示其平坦浅薄的冰底结构导致融化速率较低（10米/年），这与自主水下航行器和雷达探测的现场观测结果一致。而在思韦茨冰川舌区域，陡峭深邃的冰底地形导致模拟融化速率高达50米/年。

模拟结果与卫星反演估算值高度吻合。多项证据共同表明，控制着冰川80%物质平衡的冰川舌冰接地带正经历强烈融化。若在冰盖模型中纳入包含海水入侵过程的接地带新机制，将增强模型对海洋变暖的敏感性，从而推动海平面上升预测值的上修。

附：英文原文

Title: Contrasting melt regime in the Ice Grounding Zone of Thwaites Glacier, West Antarctica

Author: Gadi, Ratnakar, Rignot, Eric, Menemenlis, Dimitris, Scheuchl, Bernd

Issue&Volume: 2025-11-17

Abstract: The contribution of Thwaites Glacier, Antarctica, to sea level rise is influenced by how quickly warm salty seawater of Circumpolar Deep Water origin melts basal ice near its grounding line. Satellite observations reveal tidally forced kilometer-scale seawater intrusions beneath grounded ice that form an “Ice Grounding Zone” (IGZ) where ice melts vigorously. Although melt rates have been measured at selected sites using Automated phase-sensitive Radar Echo Sounders (ApRES) and Automated Underwater Vehicle (AUV) instruments, their spatial distribution and total magnitude within the IGZ remain uncertain. Here, we present 2D high-resolution simulations of the melt regime of Thwaites Glacier using the Massachusetts Institute of Technology global circulation model ocean model. The model predicts high melt at the entrance of the IGZ, with a quadratic decay inside the IGZ, a linear increase with ocean thermal forcing and a sublinear increase with cavity length. On the slow-moving Thwaites Eastern Ice Shelf, the modeled melt rate is low (10 m/y) due to a flat, shallow ice base, in agreement with in situ observations from AUV and ApRES instruments. On the Thwaites Glacier Tongue (TGT), the modeled melt rate is high (50 m/y) due to a steeper and deeper ice base. The modeled melt rates are consistent with the estimates derived from the satellite. Hence, multiple lines of evidence indicate high melt in the IGZ of TGT, which controls 80% of the glacier mass balance. An updated representation of grounding zones in ice sheet models including seawater intrusions will increase their sensitivity to ocean warming and will revise sea-level projections upward.

DOI: 10.1073/pnas.2512626122

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2512626122