EverDrill: Accessing the interior and bed of a Himalayan debris-covered glacier to forecast future mass loss

兴都库什喜马拉雅山脉是一个通常被称为第三极的地区，因为山脉中储存着大量的冰川--比地球上除北极和南极以外的任何地方都多。至关重要的是，生活在山脚下和更下游的数百万人依赖这些冰川融化的水来满足他们的日常饮用水、卫生和灌溉需求。众所周知，该地区作为一个整体对气候变化极其敏感，在高海拔地区--也就是冰川所在的地方--变暖的速度最快。然而，未来整个地区的气候可能会如何变化，以及这将对正在融化的冰川和那些在日常生活中依赖冰川的人产生什么影响，仍是一个很大的未知数。很难预测未来气候变化对该地区的影响，因为除了我们可以在表面测量的冰川之外，我们对冰川知之甚少。因此，许多旨在预测冰川演变的冰川模型假设了许多未知的参数，但这些参数对它们的运行也非常重要--例如，冰的温度、冰的厚度以及冰基岩界面处是否存在沉积物。在这个项目中，我们的目标是收集这些地下属性的真实测量，从而对这些冰川可能如何与气候发生变化做出更可靠的预测。我们将在四个地点向尼泊尔昆布冰川钻六个孔，该冰川从珠穆朗玛峰下降，是喜马拉雅地区最大的冰川之一。它最低处8公里处布满了碎片，但露出了干净的冰层，我们可以用热水钻头来开采。我们将收集每个钻孔内部的可视镜头，并在四个位置的床上安装一个多传感器阵列。这些阵列将记录水压、温度、电导率和浊度，以及这些参数如何随着季节的变化而变化。在另外两个钻孔，我们将安装冰温和倾斜绳，以确定冰川的热和变形剖面。现有的冰川模型对输入数据中的变异性敏感性测试较差。例如，与基础水压或温度的微小变化相比，了解模型对预测气候的微小变化的反应是很重要的。这些敏感性测试告诉我们预测中的不确定性，以及整个气候-冰川系统是如何工作的。我们的目标是测试我们正在使用的冰川模型对一系列不同参数的敏感性，方法是分别对它们进行调整，并分析每种情况下预测的变化。最终，我们将把我们的真实世界数据纳入模型，并对气候变暖下冰川碎片覆盖的演变做出强有力的预测。这项工作将告知关注未来供水的地区政策制定者、将在洪水和干旱时期与山脚下的居民合作的当地人道主义援助机构、将在世界舞台上为未来气候峰会提供信息的政府间气候变化专门委员会(IPCC)，以及依赖冰川径流灌溉、水电生产和卫生设施的当地人。

The Hindu-Kush Himalaya is a region that is commonly known as the 'third pole' given the volume of glacier ice that is stored in the mountains - more than anywhere on earth outside the Arctic and Antarctic. Crucially, many millions of people living in the foothills and further downstream rely on the meltwater from these glaciers for their daily drinking, sanitation and irrigation needs. The region as a whole is known to be extremely sensitive to climate change, and the speed at which warming is taking place is greatest at high-elevation - where the glacier ice is located. It is still largely unknown, however, how climate is likely to change across the region in the future, and the impact this will have on melting glacier ice and those that rely on it in their everyday lives.It is difficult to predict the impacts of future climate change in the region, because we know so little about the glaciers other than what we can measure at the surface. Many glacier models that are designed to predict glacier evolution therefore assume many of the parameters that are unknown, but these parameters are also very important to their functioning - for example the temperature of the ice, the thickness of the ice, and the existence or otherwise of sediment at the ice-bedrock interface. In this project we aim to collect real measurements of these subsurface properties and thus make much more robust predictions of how these glaciers may chance with climate. We will drill six boreholes at four locations into the Khumbu Glacier, Nepal, which descends from Mount Everest and is one of the largest in the Himalayan region. It is debris-covered for its lowermost eight kilometres but pocked with clean-ice exposures that we can exploit with a hot-water drill. We will gather visual footage of each borehole interior and install a multi-sensor array at the bed at each of the four locations. The arrays will log water pressure, temperature, electrical conductivity and turbidity and how each of these parameters changes through the seasons. At two additional boreholes we will install englacial temperature and tilt strings to determine the thermal and deformation profiles of the glacier.Existing glacier models are poorly tested to their sensitivity of variability in the input data. It is important to know how the model responds to small changes in the predicted climate for example, compared with small changes in basal water pressure or temperature. These sensitivity tests tell us about the uncertainty in our predictions as well as how the whole climate-glacier system works. We aim to test the sensitivity of the glacier model that we are using to a range of different parameters by adjusting them individually and analysing the change in prediction in each case. Ultimately, we will include our real-world data in the model and make robust predictions of debris-covered glacier evolution under a warming climate.This work will inform regional policy makers concerned with future water supply, local humanitarian aid agencies who will work with foothill dwellers in periods of flood and drought, the Intergovernmental Panel on Climate Change (IPCC) which will inform future climate summits on the world stage, and local people who are dependent on glacier runoff for irrigation, hydro-electric power production and sanitation.