美国康奈尔大学Schmidt, B. E.的小组近日取得一项新成果。经过不懈努力，他们的最新研究提出了思韦茨冰川接地线附近的非均匀融化。相关论文于2023年2月15日发表于国际顶尖学术期刊《自然》杂志上。

该课题组展示了至少从2011年到2020年的接地线后退，并解析了亚米尺度的冰架融化机制。研究结论是基于从水下航行器对思韦茨东部冰架(TEIS)的观察，从接地线向海洋延伸3公里，从冰-海洋界面延伸海底。观测结果表明，海床上有一个粗糙的冰基，向接地线方向向上倾斜，并且有一个海洋洞穴，里面最热的水超过冰点以上2°C。最接近冰基的数据表明，沿着从接地线附近开始并演变斜坡表面发生了融化加速。这种沿着陡峭的冰面发生明显融化，包括在冰缝中，产生了抑制沿着平坦界面的融化的分层。研究数据表明，依赖坡度的融化塑造了冰基，并对海洋变暖做出重要反应。

据介绍，思韦茨冰川占南极西部冰盖冰流量的15%，并影响更广泛的流域。由于思韦茨冰川位于海平面以下，因此人们认为在冰川低于海洋处的接地线(GL)处容易引发失控的退缩。最近的冰流加速和冰锋后退和接地线表明冰将继续减少。然而，近期衰退背后机制的相对影响是不确定的。

附：英文原文

Title: Heterogeneous melting near the Thwaites Glacier grounding line

Author: Schmidt, B. E., Washam, P., Davis, P. E. D., Nicholls, K. W., Holland, D. M., Lawrence, J. D., Riverman, K. L., Smith, J. A., Spears, A., Dichek, D. J. G., Mullen, A. D., Clyne, E., Yeager, B., Anker, P., Meister, M. R., Hurwitz, B. C., Quartini, E. S., Bryson, F. E., Basinski-Ferris, A., Thomas, C., Wake, J., Vaughan, D. G., Anandakrishnan, S., Rignot, E., Paden, J., Makinson, K.

Issue&Volume: 2023-02-15

Abstract: Thwaites Glacier represents 15% of the ice discharge from the West Antarctic Ice Sheet and influences a wider catchment. Because it is grounded below sea level, Thwaites Glacier is thought to be susceptible to runaway retreat triggered at the grounding line (GL) at which the glacier reaches the ocean. Recent ice-flow acceleration2,8 and retreat of the ice front and GL indicate that ice loss will continue. The relative impacts of mechanisms underlying recent retreat are however uncertain. Here we show sustained GL retreat from at least 2011 to 2020 and resolve mechanisms of ice-shelf melt at the submetre scale. Our conclusions are based on observations of the Thwaites Eastern Ice Shelf (TEIS) from an underwater vehicle, extending from the GL to 3km oceanward and from the ice–ocean interface to the sea floor. These observations show a rough ice base above a sea floor sloping upward towards the GL and an ocean cavity in which the warmest water exceeds 2°C above freezing. Data closest to the ice base show that enhanced melting occurs along sloped surfaces that initiate near the GL and evolve into steep-sided terraces. This pronounced melting along steep ice faces, including in crevasses, produces stratification that suppresses melt along flat interfaces. These data imply that slope-dependent melting sculpts the ice base and acts as an important response to ocean warming.

DOI: 10.1038/s41586-022-05691-0

Source: https://www.nature.com/articles/s41586-022-05691-0