The dramatic mountains and glaciers of the Himalayas draw visitors from around the world. ‘Himalaya’ means ‘the abode of snows’, yet many of the region’s visitors may not realize that these glaciers are themselves composed of snow, slowly transformed over time into ice. Although the compaction, metamorphism and densification of snow is well understood for many glaciers around the world, the high-altitudes where this occurs in the Himalayas (usually above 5500 m above sea level) usually limit access to hardy mountaineers. Such sites are rarely targets for glacier monitoring efforts due to the logistical complexity and time commitment involved with high-altitude work. As a result, we glaciologists still have few measurements of snowfall and glacier accumulation rates, as well as how the monsoon-dominated climate alters snow and glacier processes.
With this in mind, in November 2019 I visited a high-altitude (5750 m a.s.l.) glacier saddle above the Langtang valley of Nepal with two colleagues. We had spent months carefully preparing for our visit, but logistical challenges and changing weather conditions forced us to adapt our itinerary. When we arrived, we realised that snow conditions were not favourable for the intended route – instead, simply to get to the site required a several-pitch ice climb in order to avoid avalanche hazard. Meanwhile, our dependence on an uncooperative satellite phone made it difficult to coordinate the helicopter bringing our scientific equipment, leading to further delay. Nonetheless, we managed to borrow a functioning satellite phone, access the site safely, and arrange our equipment delivery. The setting was spectacular – Ganchempo peak towered over us, but it felt like being on the roof of the world.
Unfortunately, we were short on time for our research. Our goal was to measure the density and layering of ice near the surface of the glacier, so over three intense days we worked to extract and analyse three ice cores. We then lowered a special borehole camera into the holes we had drilled to map the layering within the glacier in each location. With these data, we are developing an optical approach to estimate ice density from borehole surveys, which will enable us to quickly measure high-altitude accumulation rates at other sites. We are thrilled to have successfully and safely collected the data needed to test our method in spite of numerous challenges.
Sometimes opportunistic science provides the most promising synergies. Just before our trip we had learned of colleagues also planning to extract and process an ice core from a glacier several valleys away. We thus sent our third ice core to Kathmandu via helicopter, which was received at the airport by our colleagues – with an ice cream truck. The core is now in Japan and will undergo isotopic and ion analyses to determine age and composition of our glacier. This will contextualize the results of our method, but will also provide our colleagues with a valuable perspective on their own results – a win-win outcome all thanks to the Polar Access Fund.