Aaron Putnam, a postdoctoral research scientist at the Lamont-Doherty Earth Observatory of Columbia University, is a leader of an expedition to Bhutan to examine links among climate, glaciers and water resources in the Himalaya.
Friday, Oct. 12
On the morning of our final day of fieldwork, the sky darkened and the temperature dropped. Our horseman Chencho Wangdi expressed concern that we would be hit by a snowstorm that would be in full force by midafternoon.
It was clear that I needed to revise or abandon my plan to collect the GPS information from all of the boulders we had sampled over the previous three days.
The main concern was for the horses. Heavy snows would cover the boulder-strewed path, making it more treacherous for the horses and mules weighed down with equipment and rocks. In addition, small, toxic rhododendron shrubs are common among the alpine plants of the Rinchen Zoe area. Grazing horses might not be able to discriminate good plants from rhododendron when the ground is obscured by snow.
I assessed how I could accomplish the final scientific objectives while also allowing for the horses and camp to be moved down to a lower, safer site.
To collect high-precision GPS data, we establish a fixed base station, which constantly logs GPS data at a single spot. While the base station continuously collects data, we use a roving hand-held device to measure the location of each sample. Both units record a time stamp for every point collected.
Once all data have been collected, the fixed base-station data are used to correct the roving sample data for the artificial drift that occurs because of atmospheric disturbances and changes in satellite geometry. This procedure reduces uncertainty and yields precise locations, within centimeters.
I figured out that all that was really needed to accomplish this task was one tent for my laptop computer and the base-station receiver. The large base-station antenna would be positioned outside the tent, where it would continually log data. I would carry the roving unit in my pack, and I would keep with me emergency provisions in case conditions became too unsafe for travel.
With Karma Tshering, our head guide, I devised a plan in which the entire camp could be packed and sent down the valley with the horses. All personnel would leave except Karma, David Putnam and Sangay, our young guide. Karma and Sangay would help to pack camp while David and I collected all GPS coordinates. Then, once all data were collected, the four of us would carry the remaining gear down to the lower camp on our backs.
With this, David and I set off into the darkening moraines. We collected coordinates beginning with the samples closest to the glacier, and systematically worked our way down valley, revisiting and measuring each sample site. Meanwhile, snow began to fall.
Shortly after 2 p.m. we measured the final coordinates on samples located at the farthest distance down valley from the glacier. By this time we spotted our team of horses, Pashupati Ssarma, Tshewang Rigzin, Sangay K., Chencho and our cook disappearing over the lip of the valley on their way down to the lower camp.
The snow was now falling heavily and beginning to stick to the ground. David and I had finished our final task, and our position was about two kilometers closer to our lower camp than when we had begun. We decided that it would be prudent for David to go directly to the lower camp rather than returning with me to high camp.
We wished each other good luck, and separated. He headed down the hill while I turned around and backtracked to our high campsite to pack up the tent and base station and join Karma and Sangay for the trip down valley.
I made it back to high camp around 3 p.m. Karma and Sangay were hunkering beneath an umbrella and next to a fire they had built during my absence. They had a cup of hot tea waiting for me. By that time the snowfall was dense and obscuring the ground, almost exactly as Chencho had predicted that morning.
I quickly gulped down the tea and began packing the remaining gear. I was delighted to see that the base station was still clicking away and recording points, and that all data had been stored successfully on the system.
I loaded my backpack with a computer and GPS receivers. Sangay and Karma loaded up with the tent and some other gear. Having packed the last of our items from high camp, we commenced a brisk walk back down valley to join the others. Karma informed me that we would be camping at Chukarpo, which is about 4,600 meters (about 15,100 feet) and two kilometers or so down valley from our previous campsite, Darlay Marpo.
Running over boulders and scree slopes, we raced mounting snow and growing darkness. We arrived at Chukarpo camp in about one and a half hours after leaving our high camp, just before sundown.
Although Chukarpo is significantly lower than our high camp at Tachanggay Tso, the elevation change was not enough to escape the snow, which continued to accumulate throughout the night. About 4 a.m., David and I awoke to our cook beating the snow from our tent. It turns out that the roof pole of the cook tent had snapped under the weight of the snow. The cook had to repair the pole using a rhododendron branch of similar diameter.
We emerged from our tent into the dark blizzard shortly after 4 a.m. and continued to sweep the ceaselessly accumulating snow from tents. The dense, continuous snow foreshadowed what could be a potentially serious challenge: We still had to surmount the 4,700-meter (about 15,400-foot) pass of Tampe La to exit the mountains.
Given that Tampe La rises even higher than our camp at Chukarpo, it was undoubtedly also accumulating snow. The sense of urgency increased among those in our camp. We needed to make it over Tampe La as soon as possible.
As the landscape brightened, the storm showed no signs of abating. Chencho gathered the horses. We packed up camp. Eventually, all set off down the rocky, snow-covered riverbed toward Galapangchu camp.
The snow cover made walking over the endless stream of slippery boulders difficult and slow. Sangay led the way, forging a least-cost path that could be followed safely by the horses.
As we lost altitude and found ourselves back in rhododendron forest, the snow became dense and wet. When jostled, each branch would shed a load of wet snow down some unfortunate person?s back. By the time we reached the mud bath of Galapangchu, nearly all members of our team were soaked to the bone from the wet snow.
Irritable horses kicked at one another while our guides scrambled to set up tents on the swampy campsite. Sangay, David, Tshewang, Ssarma and I managed to build a fire beneath an overhanging boulder. The wet wood was slow to burn and took even longer to shed any heat, but by sundown the fire became a gathering place for all in our group.
It was at this point that the formal separation between guides and clients finally broke down. Bhutanese and chillups (foreigners) alike dried their sopping clothes and warmed their bones next to the fire in primordial communal fashion.
Although the conditions were not ideal for humans or horses throughout the day, our Bhutanese friends seemed oddly cheerful. Tshewang soon informed us that this was the first snow of the year, taken as a very good omen. Our guides were interpreting this as a sign of success for our adventure and our work.
After a warm meal, David and I eventually retired to our tent, while our Bhutanese friends remained by the fire and sang songs deep into the night. After two long and hard days, all enjoyed a pleasant respite from the cold and wet.
However, still looming is the snow-covered Tampe La, which we must surmount if we hope to leave the mountains. Tomorrow we will try to journey over this pass. Only then will we know the true implications of Bhutan?s first snow of the year.
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