This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Editor’s Note: This is the second installment in a new series by Ulyana Horodyskyj, who chronicled an earlier expedition to Nepal in a series called, “Climbing Mount Everest,” which can be found by clicking here. Horodyskyj’s work focuses determining how airborne particles such as dust and soot that settle on massive glaciers alter how snow and ice melt, which could affect climate change as well as local water supplies. Other posts in this series, "Return to Nepal", can be found by clicking here.
In mid-October, Cyclone Hudhudhit the eastern coast of India, before heading up towards the Himalaya. Central Nepal was hit particularly hard, with over three feet of snow dropped in two days. Dozens of lives were lost along high mountain passes, as trekkers and guides were caught unprepared.
It is a sad situation given that the fall, particularly October, is supposed to be the best time for trekking in the mountains of Nepal: clear blue skies, decently warm temperatures, nice trail conditions. Yet this time last year, another cyclone, Phailin, also hit India and made its way up to the Himalaya, dumping three feet of snow in eastern Nepal, in the Khumbu (Everest) region. Because of the storm, I could not get to the glacial lakes of Ngozumpa glacier to work on my primary research on lake expansion and deepening, and I adapted my project to look at pollutants (black carbon and dust) present in snow and their effects on snowmelt.
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This year, the Khumbu region saw about a foot of snow due to Hudhud, enough to make trail conditions treacherous on the way to my field site around 15,500 feet elevation on the Ngozumpa, one of Nepal’s largest debris-covered glaciers, which flows off of Cho Oyu, one of Earth’s highest mountains. The trail was icy and slick in the mornings and muddy in the afternoons. I nearly lost a shoe in one instance. As I was trekking my way uphill from the town of Lukla at around 9,500 feet, I met a trekker name Joe Lazzaretti and his guide, Nawang Sherpa from Unique Adventures, who were interested in learning what I was up to, given my assortment of gear and 40-pound pack. After all, what trekker carries a paddle, raft, ice axe, and two laptops to Everest? Despite having been up to the Ngozumpa dozens of times before, and knowing the routes very well, I welcomed the help carrying gear and trailblazing through all the fresh snow.
Once we arrived at the glacier, we found some of the lakes were partially frozen while others were open water. I had left a few instruments there over the summer, during the monsoons, to track the temperature of the water, the mud on the bottoms of the lakes and the land temperatures. Excavating them proved to be quite taxing.
First, we had to make our way down to the locations, “post-holing”, or falling, through the snow, sometimes over our knees, given there was no set trail. We then had break through thin ice to get to buoys floating in the middle of the lakes. The land sensors required an hour’s work with an ice axe to get them out, as they had been buried about 1.5 feet underground in dirt and rock, which partially froze after the cyclone brought not only snow, but also temperatures below freezing. The good news was that they all recorded good data.
Initial results showed quite high temperatures of about 45 degrees Fahrenheit in “blue” lakes and quite cold temperatures of about 36 degrees in the “brown” lakes. The blue lakes have much smaller sized suspended particles in the water—think of flour—than the brown lakes, causing the color difference. This is due to the way light is either reflected or absorbed by the different sized particles.
This temperature difference means that the blue lake has a greater ability to melt ice on the bottom, simply because it is warmer. This in turn can cause the lake to deepen as more and more ice from the bottom melts away. A good thing is that given enough time, the particles suspended in the water eventually settle to the bottom, covering up the ice, which can insulate the ice from too much melt. However, a big unknown still is how thick this mud overlying the ice on the bottom may be: the thicker it is, the better it is at insulating the ice. But that is a task for a future expedition in the coming years, involving heavy equipment to pull up the mud from depth. In the meantime, once I’m back in the U.S., I will calculate ice melt through different mud thicknesses using numerical models, based on my field data.
This research reveals how lakes contribute to glacial ice volume loss in the ablation (melting) zone of the Ngozumpa glacier at the relatively low altitude of 15,500 feet, through the tracking of temperature, water level, and depth changes with time. When my two team-members, Karl and Evan, arrive in a couple of days, we will push onwards to 17,500 feet to make measurements on clean snow and ice. Using a set of spectrometers, we will be able to determine the reflectivity of the snow and ice and we’ll compare these ground results with satellite data from MODIS (Moderate Resolution Imaging Spectrometer), which will be passing overhead at the same time.
Given the large footprint or, “pixel” size on the ground of the satellite (about 1,500 square feet), we will be able to provide high-resolution data, as we will measure albedo every 100 feet or less in longitudinal transects, depending on conditions. In addition to the in-situ data, I will collect snow samples to test for pollutants, much like I did throughout last year in the Khumbu, NarPhu and Annapurna regions. We will be camping for this stretch of the expedition, so I will not be able to update this blog until our return about 10 days from now. The weather looks to be stable for the next week, so it will just be a matter of having the stamina to climb high for science!
All images courtesy of Ulyana Horodyskyj