By Shivani Majmudar
Amid this year’s global pandemic, the world is also fighting more frequent and severe hurricanes, larger wildfires and prolonged heat waves—indicative that climate change is real and it’s happening now.
“We’re at the blinking yellow light,” said Laura Mattas, a graduate research student at the University of Maine’s Climate Change Institute.
Mattas studies the Khumbu Glacier, located on the Nepalese side of the Himalayan mountain range. She’s working to identify and document its movement during the Last Glacial Maximum, the last period when ice sheets were at their greatest extent. The retreat of past glaciers provides scientists with the clues they need to predict the social and economic impact of human-driven accelerated climate change.
Her preliminary research, which she presented at this year’s virtual Comer Climate Conference, suggests this was between 18,000 and 23,000 years ago.
Glaciers are strong measures of the total energy in a system because they respond to global temperature and precipitation fluctuations. In recent decades, glaciers have retreated significantly, as Earth’s rising average temperature melts ice more quickly than snow accumulates to replace it.
Beyond a marker for change, glaciers also provide a critical human and ecological resource: freshwater. As glaciers melt, not only are oceans desalinated to some degree, impacting the viability of marine life, but freshwater flowing into the oceans is lost in the salty mix. Water that millions of people rely on for household consumption, agriculture, and electricity is slowly draining.
The ripple effect of high glacial activity can even have far-reaching impacts on economic stability. For example, the eventual depletion of a primary source of water will cause a dramatic disruption of the supply chain that serves as the backbone of the economies of China, India, and the other countries that rely on water from the Hindu-Kush-Himalaya mountain range. Consumer prices would likely rise to counterbalance the expense of importing freshwater or desalinating seawater.
Melting mountain glaciers pose the same threats across the world. Closer to home, the mountains of California and Colorado are rapidly losing snow pack. Without action to slow climate change, serious environmental, health and economic consequences remain at stake.
Mattas is one of many environmental researchers studying the past to help inform our climate future at a time when the urgency for climate policy is assaulted by wavering acceptance of science. Veteran climate scientist Richard Alley, a professor at Pennsylvania State University and the master of ceremonies for the annual Comer Climate Conference, argues that climate history is the most reliable predictor of our future environment and the strongest asset to rebuild public trust in science.
“We need to keep people’s minds on the fact that we can solve these problems if we deal with them,” Alley said. “We’ve been successful in the past when we have used science and we have gotten along with each other.”
Mattas is particularly interested in the Khumbu Glacier because of its unique location. It is surrounded by both the cold atmospheric temperatures of the Himalayan mountain range and hot air masses from the warmest waters on Earth, the Indo-Pacific warm pool. This climate positions the mountain glacier well as an incubator of climate change around the world.
Freshwater from the glaciers of the Hindu-Kush-Himalayas feeds into the largest rivers across Asia, including the Ganges and Brahmaputra in India and the Yellow and Yangtze River in China. It directly supplies water to almost 2 million people.
Mattas’ research mapping the patterns and rates of glacial activity requires a combination of field work and data analysis. In April 2019, she and her team trekked the Khumbu Glacier in Dingboche, Nepal to collect samples of moraine—a landscape of rocks, gravel, and dirt that were once embedded in a glacier’s base but are gradually deposited at the glacier’s terminal edge, leaving a trail as it moves.
Glaciers retreat first in thickness before physically melting away. The team found that the modern Khumbu Glacier has approximately 600 meters less snow accumulation than during the Last Glacial Maximum, when the glaciers began to retreat about 18,000 years ago, evidencing how the glacier is shrinking as a result of the warming climate.
Moraines, signature hedges of rock cast off by the melting glaciers, also offer valuable insight into how long ago the rock emerged from the ice and has been exposed the air. The team measures the amount of Beryllium-10 in the sample, an isotope that forms in quartz when high-energy cosmic rays in the Earth’s atmosphere hit its surface. The concentration of 10Be offers a time machine for tracking how long the rock has been ice-free. Scientists call this clock cosmogenic nucleotide dating.
Additionally, they performed detailed photogrammetry, mapping that used the highest-resolution drones to have ever captured Mount Everest. Sampling and analyzing the rocks in the moraines surrounding the modern Khumbu Glacier allowed Mattas and her team to create a chronological, geomorphologic map of the periglacial and glacial landform activity in the Dingboche, Nepal, region.
The preliminary 15 ages of moraines documented thus far suggests the timing of the Last Glacial Maximum for the Khumbu Glacier is consistent with similar research of glaciers around the world. Maps like the one Mattas has created are not only helpful for scientists to understand the rate and extent of glacial activity due to climate variability, but also serve as an important visual tool for the public and policymakers to recognize one impact of changing environmental conditions.
“[Maps] can tell us whether we need to prepare for giant floods and make flood walls or if this is a slow-moving process where we just raise the river banks,” Mattas said, The faster we can answer these questions, the better we can protect the communities who would be directly hit, she added.
Shivani Majmudar covers health, environment and science at Medill. You can follow her on Twitter @spmajmudarr.