Khumbu Glacier between Mount Everest and Mount Nuptse.
Kurt Cuffey
Khumbu Glacier descends between Mount Everest (left) and Mount Nuptse (right).

Last year for International Mountain Day, we visited the shores of Mauna Kea in Hawaii and learned that it’s the tallest mountain in the world when measured from the base underwater up to the top. This year, we are travelling to colder climates to the highest mountain in the world when measured from sea level: Mount Everest. Department of Earth and Space Sciences Howard Conway officially had one of the most scenic offices in the world when he conducted field work on the Khumbu Glacier, one of the four major glaciers that flank Mount Everest. 

Mount Everest is known locally in Tibet as “Goddess Mother of the World” or “Goddess of the Valley” which comes from its Tibetan name Chomolungma, and its Nepalese name is Sagarmatha, which translates to “Peak of Heaven”. As part of the Himalaya mountain range, Mount Everest borders China and Nepal and towers above all other peaks when measured from sea level at 29,029 feet (to put that into perspective – that is a little more than double Mount Rainier’s height). The Himalayas were formed around 60 million years ago when the Indian tectonic plate moved north and subducted under the Eurasian tectonic plate, pushing the land above it skyward. 

Khumbu Glacier is a 39,370-foot-long glacier located on the western flank of the mountain in the Khumbu region. The glacier originates from the sheer rock-surrounded “accumulation zone” 23,293 feet above sea level, where snow and ice gather before avalanching onto the rest of the glacier. Snow and ice travel through a steep icefall and start to melt at the “ablation zone” before reaching the end of the glacier 16,076 feet above sea level. Most of the ablation zone is covered with debris that has been eroded and transported by the glacier flow. In fact, over the past 55 years, the ablation zone has thinned by about 131 feet

Conway, along with colleagues, used radio echo-sounding methods to measure ice-thickness and debris-thickness in the ablation zone in order to improve understanding of erosion and the response of Himalayan glaciers to climate change. A glacier-flow model using these data indicates that even without further climate change, stagnant ice at the end of the glacier will separate from the main glacier as it retreats, with potential to form a large and possibly hazardous ice-dammed lake within a few decades. Furthermore, analyses of the debris on and beneath the glacier indicates erosion rates of about 0.028 inches per year over the past 10,000 years, which adds up to about 280 feet total.

As well as being the “Goddess Mother of the World”, the Everest region provides understanding about the effects of climate change on Himalayan glaciers, and the potential impacts on the vast population who depend on its glacier-fed rivers. Impacts include an initial increase in water due to the accelerated melting followed by diminishing supplies as the glaciers shrink, increasing threat from glacial outburst floods from ice-dammed lakes, and displacement of large populations currently living on coastal deltas in Southeast Asia due to sea-level rise. 

By looking for answers within the Khumbu Glacier, Conway and his colleagues are able to make predictions about what the future will look like for the Khumbu and the greater Southeast Asia region. Who knew that within the ice and debris that flanks the mountain lies the written history of our past, as well as a hint as to what may await us in the future?