Department of Geography, 1984 West Mall, University of British Columbia, Vancouver, British Columbia V6T 1Z2, Canada.
Department of Earth and Space Sciences and Quaternary Research Center, Box 351310, University of Washington, Seattle, Washington 98195-1310, USA.
Nature. 2015 Oct 1;526(7571):100-3. doi: 10.1038/nature15385.
Glacial erosion is fundamental to our understanding of the role of Cenozoic-era climate change in the development of topography worldwide, yet the factors that control the rate of erosion by ice remain poorly understood. In many tectonically active mountain ranges, glaciers have been inferred to be highly erosive, and conditions of glaciation are used to explain both the marked relief typical of alpine settings and the limit on mountain heights above the snowline, that is, the glacial buzzsaw. In other high-latitude regions, glacial erosion is presumed to be minimal, where a mantle of cold ice effectively protects landscapes from erosion. Glacial erosion rates are expected to increase with decreasing latitude, owing to the climatic control on basal temperature and the production of meltwater, which promotes glacial sliding, erosion and sediment transfer. This relationship between climate, glacier dynamics and erosion rate is the focus of recent numerical modelling, yet it is qualitative and lacks an empirical database. Here we present a comprehensive data set that permits explicit examination of the factors controlling glacier erosion across climatic regimes. We report contemporary ice fluxes, sliding speeds and erosion rates inferred from sediment yields from 15 outlet glaciers spanning 19 degrees of latitude from Patagonia to the Antarctic Peninsula. Although this broad region has a relatively uniform tectonic and geologic history, the thermal regimes of its glaciers range from temperate to polar. We find that basin-averaged erosion rates vary by three orders of magnitude over this latitudinal transect. Our findings imply that climate and the glacier thermal regime control erosion rates more than do extent of ice cover, ice flux or sliding speeds.
冰川侵蚀对于我们理解新生代气候变化在全球地形发育中的作用至关重要，但控制冰蚀速率的因素仍知之甚少。在许多构造活跃的山脉中，冰川被推断为具有很强的侵蚀性，冰川作用的条件被用来解释高山环境中典型的显著地形和雪线以上的山峰高度限制，即冰川拉锯。在其他高纬度地区，冰川侵蚀被认为是最小的，因为冷冰的覆盖有效地保护了景观免受侵蚀。由于基底温度和融水产生的气候控制，冰川侵蚀速率预计会随纬度的降低而增加，而融水促进了冰川滑动、侵蚀和沉积物转移。这种气候、冰川动力学和侵蚀速率之间的关系是最近数值模型的重点，但它是定性的，缺乏经验数据库。在这里，我们提出了一个综合数据集，允许明确检查控制跨越气候区的冰川侵蚀的因素。我们报告了从巴塔哥尼亚到南极半岛跨越 19 个纬度的 15 条出口冰川的沉积物产量推断出的当代冰通量、滑动速度和侵蚀速率。尽管这个广阔的地区具有相对统一的构造和地质历史，但冰川的热状况从温带到极地不等。我们发现，在这个纬度剖面上，流域平均侵蚀速率变化了三个数量级。我们的研究结果表明，气候和冰川热状况控制着侵蚀速率，而不是冰盖的范围、冰通量或滑动速度。
