Centre for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, UK.
School of Geography, University of Leeds, Leeds, UK.
Sci Rep. 2018 Nov 14;8(1):16825. doi: 10.1038/s41598-018-34327-5.
Runoff from high-elevation debris-covered glaciers represents a crucial water supply for millions of people in the Hindu Kush-Himalaya region, where peak water has already passed in places. Knowledge of glacier thermal regime is essential for predicting dynamic and geometric responses to mass balance change and determining subsurface drainage pathways, which ultimately influence proglacial discharge and hence downstream water availability. Yet, deep internal ice temperatures of these glaciers are unknown, making projections of their future response to climate change highly uncertain. Here, we show that the lower part of the ablation area of Khumbu Glacier, a high-elevation debris-covered glacier in Nepal, may contain ~56% temperate ice, with much of the colder shallow ice near to the melting-point temperature (within 0.8 °C). From boreholes drilled in the glacier's ablation area, we measured a minimum ice temperature of -3.3 °C, and even the coldest ice we measured was 2 °C warmer than the mean annual air temperature. Our results indicate that high-elevation Himalayan glaciers are vulnerable to even minor atmospheric warming.
高山覆盖着碎屑的冰川融水是兴都库什-喜马拉雅地区数百万人的重要水源，而这些地区的峰值水源已经过去。了解冰川热状况对于预测质量平衡变化的动力和几何响应以及确定地下水排泄途径至关重要，这最终会影响冰前流量，从而影响下游水资源的可用性。然而，这些冰川的深部内部冰温尚不清楚，这使得对其未来对气候变化响应的预测存在很大的不确定性。在这里，我们表明，尼泊尔的高海拔覆盖着碎屑的昆布冰川的消融区的下部可能含有约 56%的温带冰，而更冷的浅层冰大部分都接近融点温度（在 0.8°C 以内）。从冰川消融区钻取的钻孔中，我们测量到的最低冰温为-3.3°C，即使我们测量到的最冷的冰也比年平均气温高 2°C。我们的结果表明，即使是轻微的大气变暖，也会使高海拔的喜马拉雅冰川变得脆弱。
