Colorado facing a noglacier future as warmer temps rise
The final chapter of Colorado’s glacial history is being written in the drips of their last scraps of ice melting away.
As warmer temperatures creep up higher in altitude, Colorado’s 14 glaciers are melting faster and faster. Glaciers that once stored key water reserves for cities and highmountain ecology will likely be gone within the next few decades, according to researchers from the Institute of Arctic and Alpine Research (INSTAAR). Shrinking glaciers are not just a Colorado problem. In the Andes and Himalayas, similar phenomenon threatens the livelihoods and water supply for the people of the heavily populated regions.
“Glaciers are certainly still the canaries in the coal mine for climate change,” said Robert Anderson, a fellow at the Institute of Arctic and Alpine Research and a professor of geological sciences at the University of Colorado Boulder.
Millennia ago, glaciers carved out wide valleys that are now inhabited by Colorado mountain towns and forests. Today, glacier clusters are still nestled in Indian Peaks and Rocky Mountain National Park and scattered about the state’s mountains.
In the early 1900s, glacier melt fed the growth of Colorado cities. Boulder bought the Arapaho Glacier from the federal government in 1927 to secure the city’s water supply. Trekkers once ventured up to the gray chunk of ice for afternoon visits before entry was outlawed — when too much typhoid fever was making it downstream.
The Arapaho Glacier in the Indian Peaks wilderness lost over half its mass in the 20th century and may have less than 60 years left, according to the latest projections published in 2010. The Arapaho dramatically lost area in the 1900s before the thinning slowed in the early 2000s, indicating the glacier is “retreating into a corner” that is protecting the ice from the sun, according to the 2010 research.
The Arikaree Glacier will likely putter out in less than 20 years. The glacier has been thinning by about one meter per year for the last 15 years, according to INSTAAR research published in 2016. In human years, that might be enough time to grow a mullet and subsequently age out of hair altogether. But the thinning of the glaciers over the coming decades is a mere blink in their timeline.
“Colorado’s mountains have been ornamented and sculpted by the comings and goings of glaciers in our mountains for a couple million years,” said Anderson, who coauthored the 2010 paper on the Arapaho Glacier and has done research on other alpine glaciers.
Within the next few decades, most glaciers are expected to meet their watery demise. But the impact on Coloradans living below the glaciers will be negligible. Cities like Boulder no longer rely on endofsummer glacial melt for water. Many of the glaciers are short enough to be measured in feet, unlike the mileslong ice rivers that spread throughout Colorado in the ice age. In late summer, meadows will need to draw on more groundwater without the glacial backup. The plants and animals that rely on the streams will also need to adapt, Anderson said.
In South America, the same glacial razor blade slicing away at the ice threatens the water supply for countries across the continent, according to research published in the Cryosphere journal. Countries around the Andes all rely in part on glacier melt to sustain life for people living in arid regions. In the Himalayas, unstable ground left by receding glaciers could spell “chaos” for people in South Asia, said Tad Pfeffer, a fellow at INSTAAR and a University of Colorado professor who also contributed to the 2010 research on the Arapaho.
The rivers of ice that reach down from the Himalayan peaks work differently than those in Colorado. In fact, Colorado’s glaciers are not really rivers of ice at all.
In his office lined with glaciology journals and photos of snowy peaks, Pfeffer scribbled out a drawing of how alpine glaciers act like conveyor belts for extra snow on mountaintops. As unmelted snowpack accumulates and compresses into ice, the surplus slides down to lower elevations and is released as water below. In India, this process turns Himalayan ice into rivers such as the Ganges and Brahmaputra. The process is a little different in Colorado.
Colorado’s glaciers do not have much ice to slide with, Pfeffer said. The main ingredients in their survival have been wind, shade and location. Many are westward facing, allowing the glaciers to find little nooks to shield themselves from the sun and feed off icy winds that wrap around the mountaintop from the east. Snow and wind from the east blow over the rocky peaks that give shelter to the glaciers on the other side. The process is similar to snow drifts that build up next to a fence. The irony: Many of those craggy faces where the ice hides are byproducts of glacial ancestors.
Colorado will always have snow and ice on its peaks in the winter. But, “the day may very well come when we will be able to melt all the ice in the summer,” Pfeffer said.
With the wind and snow focusing on specific spots, the glaciers will likely curl up into the shadows as they morph from true glaciers into seasonal snow patches.