Nestled in the high-altitude Sayan Mountains in northern Mongolia perennial ice patches have long been central to the health of domestic reindeer and the lives of those that tend to them. Even during the hottest summer months, these “munkh mus” patches persisted, providing crucial water and cool reprieve for overheated reindeer.

But soaring temperatures in the region are melting this eternal ice at rates never seen in modern history.  

Riding by horseback, researchers took to the Ulaan Taiga Special Protected Area of Mongolia to interview first-hand eight different families of traditional reindeer herders known as Tsaatan. In this region, there are just 30 families that cultivate reindeer stocks for cheese and other food, but in the last two decades Mongolian temperatures have increased more than 1.4°C (2.5°F) above the 20th-century average – and the Tsaatan are seeing those impacts in real-time.

"What's unique about reindeer herding is how closely it's tied to this very fragile thing – the ice," said William Taylor, study author, and archaeologist with the University of Colorado, Boulder, in a statement. "The Tsaatan are literally at the front lines of climate change. These are folks that contributed nothing to the problem that we find ourselves in globally, but they're the ones paying the first price."

Between 2016 and 2018, interviewees said that for the first time in their memory, ice patches are disappearing in the height of summer. Reindeer can easily overheat and rely on munkh mus for a reprieve from the summer heat, as well as for fresh drinking water supplies and to escape disease-carrying insects. Access to these ice patches is “critical” for the health and welfare of these animals.

"Losing the ice compromises reindeer health and hygiene and leaves them more exposed to disease, and impacts the well-being of the people who depend on the reindeer,” said veterinary researcher and study co-author Jocelyn Whitworth.

Early history and prehistory of the Tsaatan is poorly understood and the region’s harsh climate and active geology make finding archaeological artifacts difficult. Writing in PLOS ONE, the researchers found several artifacts while conducting archaeological surveys at 11 melting ice patches, including a wooden-carved rod that local interviewees say may have been used as an ancient fishing pole. As the ice melts, the researchers worry that archaeological evidence of reindeer herding could be lost forever, highlighting how climate change threatens the world’s cultural heritage.

"These accumulations of ice and snow freeze objects that have fallen inside, preserving them to create one of our only archaeological datasets from this key region," said Taylor. "If we lose these unique cultural systems and ways of life, we're losing the diversity of approaches and knowledge that we have as a species to deal with the future.

The Tsaatan may be isolated geographically, but the study authors note that their climate change plight may not be a solo occurrence. Similar communities around the world who rely on snowpack for their livelihood – from the cities of the Rocky Mountains to communities in the remote Arctic – could face a growing list of challenges in the years to come.