Editor’s Note: This is the fifth and final post in a series by geologist Ulyana Horodyskyj. She climbed several peaks in the Himalaya Mountains to try to determine 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. She finally returned to the University of Colorado, Boulder, just a few days ago. Her thoughts on the data, and the trek itself, are below.

BOULDER, COLORADO—Many thanks to all the readers who have followed this blog over the past two months. I have just returned to Colorado after having spent nearly a year abroad doing research in the Himalayas. The expedition was challenging in many ways, including the unpredictable weather, which forced changes in field plans, sometimes at the last minute. Back in October, for example, a large cyclone off the coast of India made its way across the continent. When it slammed up against the Himalayas, more than a meter of snow fell in a matter of days. This shut down trails in the Khumbu Valley where we were working and partially froze the glacial lakes I monitor, making it impossible to conduct some of my research.

However, the large amount of snow sparked an idea: to test the snowpack just days after the storm for any localized pollutants, and to track albedo (reflectivity) changes in the snow with time. Armed with filters and syringes, my team of Kami Sherpa, Emma Marcucci and Marty Coleman and I collected snow samples surrounding the villages nearby to the Ngozumpa glacier. We were astonished by the amount of dust and black carbon present on the filters, so soon after the storm. Marty and I set up a mini weather station with pyranometers (instruments that measure solar radiation flux) to track the accompanying albedo changes. Perfect reflection would be 100 percent, but snow is not a uniform substance—it can be filled with air and some meltwater pockets, so fresh snowfall, at its maximum, is 90 percent reflective. After returning in December to check on my experiment, I found that despite dropping temperatures, the albedo had decreased by nearly 20 percent because of the accumulation of deposits.

These results, collected at about 16,500 feet, prompted more ideas. What are the altitudinal effects, if any, of this dust and carbon deposition? To find out, Ang Tendi Sherpa (of Mega Adventures International) and I in December worked on a nearby peak to collect samples at up to 20,000 feet. We again found dirty snow, consisting of a mixture of dust (locally, from trails) and black carbon (either localized from villages, or from Kathmandu lower down the valley).

Our planned trip up Mount Everest was to take us even higher, to more than 25,000 feet. But a tragic avalanche struck just above the base camp there, right before we arrived at the camp ourselves. It killed 16 people, including our team member, Asman Tamang. We could not, in good conscience, continue on with our climb.

We restricted our work to the lower parts of the Khumbu glacier, collecting more snow and spectral information on that snow, to compare with samples I had collected during the fall and winter in other parts of the range. To do this, we used a handheld portable spectrometer from PANalytical, Inc., which measures the reflectivity of snow across the visible and near-infrared parts of the electromagnetic spectrum. By taking measurements at the same time of day, under similar sky conditions (minimal cloud cover), we can quantify the diversity of reflection of snow in a small area. This is important, because dust and black carbon deposition lowers reflectivity and can lead to different rates of melting.

We had to regroup, after the avalanche, and get new climbing permits; in early May we switched targets to Mount Himlung, a peak in central Nepal. There we continued with the collection of snow samples at varying altitudes, up to slightly above Camp 2, around 20,000 feet again. This would provide us with information on dust and black carbon deposits in a different part of the Himalayan range, further west of Everest. We had hoped to sample about 3,000 feet higher, but then our team member John All fell 70 feet down into a crevasse and sustained some serious injuries. Given his evacuation, and snow conditions that were becoming increasingly unstable as the spring invaded, the safer alternative was to get all the gear and ourselves off the mountain before heavier spring melting and the start of the monsoons.

After decompressing in Kathmandu for a few days I made one final push to the Ngozumpa glacier, where the work all started. I was with a small team of members from Midwest ROV LLC (Patrick Rowe, Cecil Goodson), the American Climber Science Program (David Byrne, a climber-scientist volunteer from the Everest and Himlung expeditions), Kathmandu University (masters-degree student Rakesh Kayastha) and Thamserku Trekking (head guide, Chhewang Sherpa). Together, we downloaded data from a weather station that was tracking albedo changes, air temperatures and relative humidity on the glacier. We also recaptured a handful of buoys in the lake waters that had been tracking temperature and water level changes throughout the year. And we had fun rowing an inflatable kayak on the lakes, which rise and fall as they fill and discharge, collecting more information on the depths of these lakes and how they have been changing in recent years, compared with measurements by previous researchers.

How do these projects relate? Lakes continue to grow and deepen on the ends of debris-covered glaciers in the Himalayas, effectively “eating away” at them. Yet higher up, at the other “end,” snow and ice may still be accumulating, feeding the glaciers lower down. Our results, to be processed in the lab in the coming months, will reveal how much black carbon may be sequestered up high in the clean snow and ice, and how that may affect melting in the future.

Together these studies reveal how quickly the top of the world is changing. But the question remains: What can we do about it?

Links to the first four installments:

April 7: My Search for Dirty Snow

April 18: Base Camp Bound, After a Glacial Detour

May 1: Hostility Follows Deadly Avalanche

June 17: Risking Life and Limb for Science

All images courtesy of the author.