Many mountain glaciers carry some amount of rocky debris on them, which modifies surface ablation rates. The debris is typically derived from erosion of the surrounding topography and its supraglacial extent is predominantly controlled by the relative accumulation rates of debris versus snow. Because Global Warming results in shrinking glaciers as well as thawing permafrost worldwide, changes in both rates will most likely affect the evolution of supraglacial debris cover and thus the response of glaciers to climate change. Here we report ¹⁰Be concentrations measured in five amalgamated debris samples collected from the main medial moraine of the Chhota Shigri Glacier, India. Results suggest headwall erosion rates that are ~0.5–1 mm year⁻¹, and apparently increasing (¹⁰Be concentrations are decreasing) toward the present. We employed a numerical ice flow model that we combined with a new Lagrangian particle tracing routine to explore the impact of spatial and temporal variability in erosion rates and source areas on ¹⁰Be concentrations in the medial moraine. Our modeling results show that neither changes in source areas, related to the transient response of the glacier to ongoing climate change, nor four different scenarios of spatial and temporal variability in erosion rates could explain the observed trend in ¹⁰Be concentrations. Although not accounted for in our modeling explicitly, we suggest that the observed trend could be due to transiently enhanced erosion of recently deglaciated areas, or to greater spatial variability in erosion rates than explored in our models.

中文翻译：

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冰川上碎片的生产和运输：宇宙成因10Be和数值模拟的启示，印度喜马拉雅山Chhota Shigri冰川

许多高山冰川上都带有一定数量的岩石碎屑，从而改变了表面消融速率。碎片通常来自周围地形的侵蚀，其冰川作用范围主要由碎片与积雪的相对累积速率控制。由于全球变暖会导致冰川萎缩以及全球范围内的永久冻土融化，因此两种速率的变化很可能会影响冰川带碎片覆盖的演变，进而影响冰川对气候变化的响应。在这里，我们报告了从印度Chhota Shigri冰川的主要内侧冰ora中收集的五个混合碎片样品中测得的¹⁰ Be浓度。结果表明，- ¹年头壁侵蚀速率约为0.5-1 mm ，并且明显增加（¹⁰浓度正在下降）。我们采用了数值冰流模型，并与新的拉格朗日粒子追踪程序相结合，以探索侵蚀速率和源区的时空变化对冰on中部¹⁰ Be浓度的影响。我们的模拟结果表明，源区的变化（与冰川对持续的气候变化的瞬态响应有关），以及侵蚀速率的时空变化的四种不同情况都不能解释观测到的¹⁰趋势。被集中。尽管在我们的模型中没有明确说明，但我们建议观察到的趋势可能是由于最近冰期地区的侵蚀暂时增强，或者是侵蚀速率的空间变异性大于我们的模型所探讨的。