By Eric Keenan, U. Washington, and Christoph Suhr, Whitman College
One method that scientists use to evaluate the health of glaciers is by digging holes into the glacier surface. On the Juneau Icefield Research Program, students and scientists use this method - known as mass balance - to determine the total amount of water in the form of ice and snow that has accumulated at pre-determined points on the Juneau Icefield in the past year. These measures have been collected since 1948, forming the second longest lasting mass balance record in the world. Recently, fifteen students, faculty, and staff embarked on a three day expedition to the Northwest Branch of Taku Glacier to carry on a part of this long-term survey.
To reach the pits on the NW Branch of Taku Glacier, our group skied approximately thirteen kilometers from Camp 10, and established an overnight basecamp complete with dug-out tent platforms, latrines, sheltered gear trenches, and a cook tent. The second day of the expedition consisted of digging the mass balance pits higher up the NW Branch of Taku Glacier, too far afield to access in a day trip from any permanent JIRP camp. On the third and final day of the expedition we awoke to sunny skies, packed up our camp, and enjoyed the beautiful weather for our ski back to Camp 10.
To conduct the mass balance research, on each day of the expedition the fifteen participants would split into three groups, and head from basecamp to different locations to dig their mass balance pits. To document the health of the glacier, the students and scientists dug tirelessly down to the previous summer’s surface, sometimes having to dig over four meters into the glacier! By reaching the previous summer’s surface, the students could sample the snow that fell in the past year, weigh it, and from those data calculate the total mass of ice and snow that was added to that part of Taku Glacier by snowfall. With this information, total mass of snow and ice added in the winter can be compared with the mass of ice lost to summer melt. This comparison can be thought of as ‘balancing the glaciers checkbook,’ and can be used to evaluate the glacier’s health.